TH
Tom Holmes
Tue, Jun 30, 2020 2:09 AM
Hi Ethan…
Very cool! It would be interesting to see more on it all. I’m not a photographer type at all but it is interesting to see what is done optically compared to at RF.
I once did a spectrum analyzer training class for the Navy in MD that was dealing with dishes looking upwards. They were somewhat secretive about what they were doing, so we settled on calling it radio astronomy. At one point they showed me a 70’ dish that could go from horizon to horizon in like 2 minutes. They claimed it was the fastest moving dish on the planet. I’ve yet to find any stars or planets that move that quickly (wink-wink). At least they didn’t have to shoot me when the class was over.
Tom Holmes, N8ZM
From: Ethan Miller K8GU ethan@k8gu.com
Sent: Monday, June 29, 2020 9:59 PM
To: Midwest VHF/UHF Society Mailing List mvus-list@lists.febo.com
Cc: Tom Holmes tholmes@woh.rr.com
Subject: Imagery (was Re: [mvus-list] Arecibo HF)
Tom,
Like "Fight Club," the first rule of UFOs is "don't talk about the UFOs."
I don't currently have any equipment to do all-sky imaging. There are several commercial sources and the pricing is from ~$10K to ~$100K. The basic design is a fast off-the-shelf (f/2.8 or better) fisheye lens combined with some carefully-designed fixed lenses to produce telecentric rays through a bank of high-quality narrow-band interference filters (e.g., 2-nm bandwidth at half-max, OD5 in the stop-band, usually with other requirements on film quality, etc; very custom). The filters are between 2 and 4 inches in diameter, so the telecentric requirement is pretty stringent for many designs to keep the filter wavelength from shifting across the image. The filters are often selectable by a motorized filterwheel. Then, there are some more custom fixed optics that focus the telecentric rays back onto the imaging detector. The precise choice of detector depends a lot on the science you're trying to do. My experience has been predominantly with consumer astronomical CCDs and CMOS detectors from Atik, SBIG, and Andor (a little better than "consumer-grade"). I'll see if I can find pictures of some of the instrumentation for you if you'd like to geek out on it.
The emissions we're looking at usually pretty faint and require long integration (exposure) times to overcome measurement noise. The 630-nm "red line" emission comes from an excited state of oxygen that's observed in both the aurora and the airglow. Airglow is a by-product of the plasma process of recombination, which is the reverse of production (ionization), which is what the Sun does to create the ionosphere in the first place. Red airglow comes from just below the peak plasma density of the F2 region, about 250 km up. Green airglow (557.7 nm) is a brighter oxygen emission and comes from the E region, about 97 km altitude. If you've seen astronomical photos of waves in the night sky, these are probably green airglow. This is also the photochemistry as the green aurora, although the driving process is the magnetosphere, not diurnal recombination.
I've been "inside the fence" at Haleakala. I was a grad student at the time and my advisor dropped into my office one day and said, "How do you feel about going to Hawaii?" I responded affirmatively. The following day, he came in and said, "How's Monday?" My host/minder was an USAF contractor who had been an MP in Bosnia. The instrumentation (two separate cameras) resided in several "huts" that could only be accessed by passing through secure areas. The big dial locks on the doors made an impression for sure. I don't think there would have been much "talking your way in," at least on the Air Force side. Their telescope can do things that the one on the astronomy side can't. It moved really fast when they demo'ed it for me. Of course, the night sky was amazing, too, with the clouds below you.
Did that scratch the itch? Now I'm getting wanderlust...
73,
--Ethan, K8GU.
On Mon, Jun 29, 2020 at 7:00 PM Tom Holmes via mvus-list <mvus-list@lists.febo.com mailto:mvus-list@lists.febo.com > wrote:
Ethan...
Cool video, but don’t understand why the UFO's are moving but not the stars 😉.
Can you talk more about the hardware you have to do this?
Have been to Haleakala a couple of times, but always had family so didn’t make the effort to bluff my way into the observatory. Would have loved to see it. I have been to Kitt's Peak in AZ, and to the VLA, both of which are quite fascinating, each in their own way.
Tom Holmes, N8ZM
-----Original Message-----
From: mvus-list <mvus-list-bounces@lists.febo.com mailto:mvus-list-bounces@lists.febo.com > On Behalf Of Ethan Miller K8GU via mvus-list
Sent: Monday, June 29, 2020 6:44 PM
To: Midwest VHF/UHF Society Mailing List <mvus-list@lists.febo.com mailto:mvus-list@lists.febo.com >
Cc: Ethan Miller K8GU <ethan@k8gu.com mailto:ethan@k8gu.com >
Subject: Re: [mvus-list] Arecibo HF
Dana,
Cool. Yes, there's quite a bit of mutual coupling in this system!
I'm vaguely familiar with the source of the transmitters (I was
involved with putting a newer instrument at the location of the West
Coast counterpart), but have not gotten into the details of the feeds,
antennas, etc. It's neat to hear the backstory on the role that you
and Daun played!
Here is a link to a time-lapse movie taken at the Observatory (for
whatever reason, I can't lay my hands on data from the Culebra
instrument during heating right now). About 24 seconds into the
movie, you'll see a white spot in the center of the field of view
blinking ON and OFF. That's the HF.
http://k8gu.com/webpost/ao151109_6300.avi http://k8gu.com/webpost/ao151109_6300.avi
I believe the Arecibo imager was only looking at the 630-nm emission
and my camera was configured for 557.7-nm, 589.3-nm, and OH broadband
in the near-IR. Because this is a filterwheel system, each additional
wavelength reduces temporal sampling. It becomes burdensome at the
four-minute exposures we were doing! In case you wondered, for some
reason, this imager is also out of focus. Mine was never that bad!
The Culebra site is quite good for the Caribbean, better than Arecibo,
but perhaps comparable to Bonaire, which is dry and not too overrun
with tourists and hotels. It is nothing like a number of other
optical sites where I've operated equipment, for example Cerro Tololo,
Chile, and Haleakala, Hawaii. I have not been to the new site that
they negotiated after the new management came in a couple of years
ago. I'll try to drag out some more heating imagery and see what I
have that I've never looked at. Believe it or not, my HF receiving
data from Culebra has been more interesting than the imagery so far.
We originally installed the imager to study a certain class of
traveling ionospheric disturbances that are pretty commonly observed
over Puerto Rico. There is a paper on this coming out in J. Geophys.
Res. soon, led by Pedrina Santos, of Arecibo.
The airport approach into CPX is pretty cool...going through that
little pass that's not-quite-aligned with the runway! My coworker and
I flew over on a Cape Air BN-2B Islander from SJU and had 4-5 Pelican
cases full of gear. The pilot very carefully balanced the plane
before we took off and I think we may have bumped another passenger.
That was a great trip.
73,
--Ethan, K8GU.
On Mon, Jun 29, 2020 at 5:42 PM Dana Whitlow via mvus-list
< <mailto:mvus-list@lists.febo.com mailto:mvus-list@lists.febo.com > mvus-list@lists.febo.com mailto:mvus-list@lists.febo.com > wrote:
What got me interested in "seeing" the light emission resulting from
Arecibo's HF system was in search of a better, more practical solution to
problem of properly phasing the transmitters' outputs into their respective
in the array. I designed the multi-phase splitter for Arecibo while still
there, and Daun pretty much built the whole thing hardware-wise. But the
is that the dipoles talk to each other, and the driving impedance presented
dipole's feed point is not infinity, so radiation from each dipole
and phases of the currents in all the other dipoles, ad nauseum.
One option is careful system simulation, and I have put some effort into
frankly it's not looking like a viable solution to me. Too many
guesses are involved. BTW, does anybody have a good Spice model for a
4CW150,000E power tetrode?
Another is direct measurement of the feed point complex currents with
coils (or similar sensors), but this is not trivial and would require the
of significant funds in the sensors and in phase-matched cables running
the TX building. Nevertheless I suspect this is the best way.
Another, that is more economical, is to make all the transmission lines an
integer number of half waves, and make the measurements at the TX end of the
cables. I worked out a way of doing the measurements with dual-directional
of which sufficient extras came installed in the transmitters. I used this
for trimming our feedlines to the same "length" (although they could differ
integer multiples of a half-wave), and it looked very promising. But using
in actual operation requires building a bunch of additional electronics,
yet had the time or money to do so.
So, at present the technique used is to measure amplitude and phase of the
wave (only) at the TX end of each line, basically by hand, and
transmitters' drive signals until we're happy with the results. This
working OK, but we don't know for sure, and it's a royal pain to do in any
real problem is that this method does not really account for interactions
dipoles, especially given that the transmitters' output are "power
impedance matched). BTW, does anybody have a good Spice model for a
The means for setting phases is via computer control of the stuff that Daun
with a Python program written by another engineer (who has also left the
But now, I can get to my other idea for optimizing phasing, which is to
emitted light in real time and crank on the "knobs" until the spot becomes
most compact. It could even be done with a camera at a very remote
internet, thus allowing a camera location where the skies are really dark.
Culebra site comes to mind for this.
On Sun, Jun 28, 2020 at 6:58 AM Ethan Miller K8GU via mvus-list <
Sorry I missed the MVUS showing of Arecibo photos. I had an HF
receiver and a relatively sensitive all-sky (fisheye) imager (the
imager is still there but operated by someone else now) in Culebra for
a couple of years (for a different experiment) that was occasionally
repurposed for Arecibo HF experiments. It's pretty wild to see some
of the ionospheric structures they created with the HF system,
including airglow structures that were sub-visual magnitude blinking
on and off with the HF transmitter. Of course, at HAARP they've done
visual magnitude airglow, which does nothing to quell the conspiracy
I'm not a hard-core plasma physicist, but the stimulated RF emissions
from the Arecibo HF were also always interesting to see...the
high-power HF mode converts into plasma waves which interact with each
other and some of them mode convert back into electromagnetic waves at
different frequencies, shifted by "natural frequencies" (for example
the electron gyrofrequency) of the plasma. These are the types of
things that are theorized to be explanations for long-delayed echoes
(LDEs) and other radio oddities. I'll have to see if I have any data
floating around still that is clear and illustrative to a
technically-literate non-expert audience...
On Sun, Jun 28, 2020 at 1:56 AM Lenny via mvus-list
Just wondering if I can use the pictures and description in the Mt Airy
VHF Radio Club ("The Packrats") newsletter. I'm sure the members would
Please let me know either way.
--Lenny W2BVH (newsletter editor)
On 6/27/2020 4:28 PM, Daun Yeagley via mvus-list wrote:
It's "fun" trying to sort through all my pictures from Arecibo, as
they are stored by date, and who knows what I was doing on a
Anyway, here are some pictures of the HF transmitters, and the
antennas in the bottom of the dish. For scale, look for the guys
that are standing in the opening in the middle. (that's where they
hoist stuff up to the platform). Also, on the last one, if you look
carefully you can see the cables that make up the secondary reflector.
Repair. Re-use. Re-purpose. Recycle.
Hi Ethan…
Very cool! It would be interesting to see more on it all. I’m not a photographer type at all but it is interesting to see what is done optically compared to at RF.
I once did a spectrum analyzer training class for the Navy in MD that was dealing with dishes looking upwards. They were somewhat secretive about what they were doing, so we settled on calling it radio astronomy. At one point they showed me a 70’ dish that could go from horizon to horizon in like 2 minutes. They claimed it was the fastest moving dish on the planet. I’ve yet to find any stars or planets that move that quickly (wink-wink). At least they didn’t have to shoot me when the class was over.
Tom Holmes, N8ZM
From: Ethan Miller K8GU <ethan@k8gu.com>
Sent: Monday, June 29, 2020 9:59 PM
To: Midwest VHF/UHF Society Mailing List <mvus-list@lists.febo.com>
Cc: Tom Holmes <tholmes@woh.rr.com>
Subject: Imagery (was Re: [mvus-list] Arecibo HF)
Tom,
Like "Fight Club," the first rule of UFOs is "don't talk about the UFOs."
I don't currently have any equipment to do all-sky imaging. There are several commercial sources and the pricing is from ~$10K to ~$100K. The basic design is a fast off-the-shelf (f/2.8 or better) fisheye lens combined with some carefully-designed fixed lenses to produce telecentric rays through a bank of high-quality narrow-band interference filters (e.g., 2-nm bandwidth at half-max, OD5 in the stop-band, usually with other requirements on film quality, etc; very custom). The filters are between 2 and 4 inches in diameter, so the telecentric requirement is pretty stringent for many designs to keep the filter wavelength from shifting across the image. The filters are often selectable by a motorized filterwheel. Then, there are some more custom fixed optics that focus the telecentric rays back onto the imaging detector. The precise choice of detector depends a lot on the science you're trying to do. My experience has been predominantly with consumer astronomical CCDs and CMOS detectors from Atik, SBIG, and Andor (a little better than "consumer-grade"). I'll see if I can find pictures of some of the instrumentation for you if you'd like to geek out on it.
The emissions we're looking at usually pretty faint and require long integration (exposure) times to overcome measurement noise. The 630-nm "red line" emission comes from an excited state of oxygen that's observed in both the aurora and the airglow. Airglow is a by-product of the plasma process of recombination, which is the reverse of production (ionization), which is what the Sun does to create the ionosphere in the first place. Red airglow comes from just below the peak plasma density of the F2 region, about 250 km up. Green airglow (557.7 nm) is a brighter oxygen emission and comes from the E region, about 97 km altitude. If you've seen astronomical photos of waves in the night sky, these are probably green airglow. This is also the photochemistry as the green aurora, although the driving process is the magnetosphere, not diurnal recombination.
I've been "inside the fence" at Haleakala. I was a grad student at the time and my advisor dropped into my office one day and said, "How do you feel about going to Hawaii?" I responded affirmatively. The following day, he came in and said, "How's Monday?" My host/minder was an USAF contractor who had been an MP in Bosnia. The instrumentation (two separate cameras) resided in several "huts" that could only be accessed by passing through secure areas. The big dial locks on the doors made an impression for sure. I don't think there would have been much "talking your way in," at least on the Air Force side. Their telescope can do things that the one on the astronomy side can't. It moved really fast when they demo'ed it for me. Of course, the night sky was amazing, too, with the clouds below you.
Did that scratch the itch? Now I'm getting wanderlust...
73,
--Ethan, K8GU.
On Mon, Jun 29, 2020 at 7:00 PM Tom Holmes via mvus-list <mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> > wrote:
Ethan...
Cool video, but don’t understand why the UFO's are moving but not the stars 😉.
Can you talk more about the hardware you have to do this?
Have been to Haleakala a couple of times, but always had family so didn’t make the effort to bluff my way into the observatory. Would have loved to see it. I have been to Kitt's Peak in AZ, and to the VLA, both of which are quite fascinating, each in their own way.
Tom Holmes, N8ZM
-----Original Message-----
From: mvus-list <mvus-list-bounces@lists.febo.com <mailto:mvus-list-bounces@lists.febo.com> > On Behalf Of Ethan Miller K8GU via mvus-list
Sent: Monday, June 29, 2020 6:44 PM
To: Midwest VHF/UHF Society Mailing List <mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> >
Cc: Ethan Miller K8GU <ethan@k8gu.com <mailto:ethan@k8gu.com> >
Subject: Re: [mvus-list] Arecibo HF
Dana,
Cool. Yes, there's quite a bit of mutual coupling in this system!
I'm vaguely familiar with the source of the transmitters (I was
involved with putting a newer instrument at the location of the West
Coast counterpart), but have not gotten into the details of the feeds,
antennas, etc. It's neat to hear the backstory on the role that you
and Daun played!
Here is a link to a time-lapse movie taken at the Observatory (for
whatever reason, I can't lay my hands on data from the Culebra
instrument during heating right now). About 24 seconds into the
movie, you'll see a white spot in the center of the field of view
blinking ON and OFF. That's the HF.
<http://k8gu.com/webpost/ao151109_6300.avi> http://k8gu.com/webpost/ao151109_6300.avi
I believe the Arecibo imager was only looking at the 630-nm emission
and my camera was configured for 557.7-nm, 589.3-nm, and OH broadband
in the near-IR. Because this is a filterwheel system, each additional
wavelength reduces temporal sampling. It becomes burdensome at the
four-minute exposures we were doing! In case you wondered, for some
reason, this imager is also out of focus. Mine was never that bad!
The Culebra site is quite good for the Caribbean, better than Arecibo,
but perhaps comparable to Bonaire, which is dry and not too overrun
with tourists and hotels. It is nothing like a number of other
optical sites where I've operated equipment, for example Cerro Tololo,
Chile, and Haleakala, Hawaii. I have not been to the new site that
they negotiated after the new management came in a couple of years
ago. I'll try to drag out some more heating imagery and see what I
have that I've never looked at. Believe it or not, my HF receiving
data from Culebra has been more interesting than the imagery so far.
We originally installed the imager to study a certain class of
traveling ionospheric disturbances that are pretty commonly observed
over Puerto Rico. There is a paper on this coming out in J. Geophys.
Res. soon, led by Pedrina Santos, of Arecibo.
The airport approach into CPX is pretty cool...going through that
little pass that's not-quite-aligned with the runway! My coworker and
I flew over on a Cape Air BN-2B Islander from SJU and had 4-5 Pelican
cases full of gear. The pilot very carefully balanced the plane
before we took off and I think we may have bumped another passenger.
That was a great trip.
73,
--Ethan, K8GU.
On Mon, Jun 29, 2020 at 5:42 PM Dana Whitlow via mvus-list
< <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> > mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> > wrote:
>
> Ethan,
>
> What got me interested in "seeing" the light emission resulting from
> operation of
> Arecibo's HF system was in search of a better, more practical solution to
> the
> problem of properly phasing the transmitters' outputs into their respective
> dipoles
> in the array. I designed the multi-phase splitter for Arecibo while still
> employed
> there, and Daun pretty much built the whole thing hardware-wise. But the
> problem
> is that the dipoles talk to each other, and the driving impedance presented
> to each
> dipole's feed point is not infinity, so radiation from each dipole
> affects the amplitudes
> and phases of the currents in all the other dipoles, ad nauseum.
>
> One option is careful system simulation, and I have put some effort into
> this, but
> frankly it's not looking like a viable solution to me. Too many
> imponderables and
> guesses are involved. BTW, does anybody have a good Spice model for a
> 4CW150,000E power tetrode?
>
> Another is direct measurement of the feed point complex currents with
> Rogowski
> coils (or similar sensors), but this is not trivial and would require the
> expenditure
> of significant funds in the sensors and in phase-matched cables running
> back to
> the TX building. Nevertheless I suspect this is the best way.
>
> Another, that is more economical, is to make all the transmission lines an
> exact
> integer number of half waves, and make the measurements at the TX end of the
> cables. I worked out a way of doing the measurements with dual-directional
> couplers,
> of which sufficient extras came installed in the transmitters. I used this
> basic technique
> for trimming our feedlines to the same "length" (although they could differ
> in length by
> integer multiples of a half-wave), and it looked very promising. But using
> the technique
> in actual operation requires building a bunch of additional electronics,
> and nobody has
> yet had the time or money to do so.
>
> So, at present the technique used is to measure amplitude and phase of the
> *forward*
> *wave* (only) at the TX end of each line, basically by hand, and
> iteratively tweak on the
> transmitters' drive signals until we're happy with the results. This
> actually *seems* to be
> working OK, but we don't know for sure, and it's a royal pain to do in any
> case. The
> real problem is that this method does not really account for interactions
> between the
> dipoles, especially given that the transmitters' output are "power
> matched", (not
> impedance matched). BTW, does anybody have a good Spice model for a
> 4CW150,000E
> power tetrode?
>
> The means for setting phases is via computer control of the stuff that Daun
> put together,
> with a Python program written by another engineer (who has also left the
> observatory).
>
> But now, I can get to my other idea for optimizing phasing, which is to
> view the spot of
> emitted light in real time and crank on the "knobs" until the spot becomes
> brightest and
> most compact. It could even be done with a camera at a very remote
> location via the
> internet, thus allowing a camera location where the skies are really dark.
> Naturally the
> Culebra site comes to mind for this.
>
> Dana
>
>
> On Sun, Jun 28, 2020 at 6:58 AM Ethan Miller K8GU via mvus-list <
> <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> > mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> > wrote:
>
> > Daun/Dana,
> >
> > Sorry I missed the MVUS showing of Arecibo photos. I had an HF
> > receiver and a relatively sensitive all-sky (fisheye) imager (the
> > imager is still there but operated by someone else now) in Culebra for
> > a couple of years (for a different experiment) that was occasionally
> > repurposed for Arecibo HF experiments. It's pretty wild to see some
> > of the ionospheric structures they created with the HF system,
> > including airglow structures that were sub-visual magnitude blinking
> > on and off with the HF transmitter. Of course, at HAARP they've done
> > visual magnitude airglow, which does nothing to quell the conspiracy
> > theories!
> >
> > I'm not a hard-core plasma physicist, but the stimulated RF emissions
> > from the Arecibo HF were also always interesting to see...the
> > high-power HF mode converts into plasma waves which interact with each
> > other and some of them mode convert back into electromagnetic waves at
> > different frequencies, shifted by "natural frequencies" (for example
> > the electron gyrofrequency) of the plasma. These are the types of
> > things that are theorized to be explanations for long-delayed echoes
> > (LDEs) and other radio oddities. I'll have to see if I have any data
> > floating around still that is clear and illustrative to a
> > technically-literate non-expert audience...
> >
> > 73,
> >
> > --Ethan, K8GU.
> >
> > On Sun, Jun 28, 2020 at 1:56 AM Lenny via mvus-list
> > < <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> > mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> > wrote:
> > >
> > > Hi Daun
> > >
> > > Just wondering if I can use the pictures and description in the Mt Airy
> > > VHF Radio Club ("The Packrats") newsletter. I'm sure the members would
> > > be interested.
> > >
> > > Please let me know either way.
> > >
> > > Tnx, 73 & stay safe,
> > >
> > > --Lenny W2BVH (newsletter editor)
> > >
> > >
> > >
> > > On 6/27/2020 4:28 PM, Daun Yeagley via mvus-list wrote:
> > > > It's "fun" trying to sort through all my pictures from Arecibo, as
> > > > they are stored by date, and who knows what I was doing on a
> > > > particular day!
> > > >
> > > > Anyway, here are some pictures of the HF transmitters, and the
> > > > antennas in the bottom of the dish. For scale, look for the guys
> > > > that are standing in the opening in the middle. (that's where they
> > > > hoist stuff up to the platform). Also, on the last one, if you look
> > > > carefully you can see the cables that make up the secondary reflector.
> > > >
> > > > Daun
> > > >
> > > >
> > > > _______________________________________________
> > > > mvus-list mailing list
> > > > <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> > mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
> > > > <http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com> http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
> > > _______________________________________________
> > > mvus-list mailing list
> > > <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> > mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
> > > <http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com> http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
> >
> >
> >
> > --
> > <http://www.k8gu.com/> http://www.k8gu.com/
> > Repair. Re-use. Re-purpose. Recycle.
> >
> > _______________________________________________
> > mvus-list mailing list
> > <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> > mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
> > <http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com> http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
> >
> _______________________________________________
> mvus-list mailing list
> <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> > mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
> <http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com> http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
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Repair. Re-use. Re-purpose. Recycle.
_______________________________________________
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Repair. Re-use. Re-purpose. Recycle.
DW
Dana Whitlow
Tue, Jun 30, 2020 2:12 AM
Ethan,
What is the bandwidth of typical filters used in upper atmosphere
studies?
You've made a couple of references to long time exposures. Yet
watching the videos of Arecibo-driven light emission while I was
there gave me the distinct impression that this was normal video
at normal frame rates. Was that just wishful thinking on my part?
Note that I've not yet watched the video you attached- the only
PC I have that may be able to play AVI format is rather busy at the
moment doing other things.
Dana
On Mon, Jun 29, 2020 at 8:59 PM Ethan Miller K8GU via mvus-list <
mvus-list@lists.febo.com> wrote:
Tom,
Like "Fight Club," the first rule of UFOs is "don't talk about the UFOs."
I don't currently have any equipment to do all-sky imaging. There are
several commercial sources and the pricing is from ~$10K to ~$100K. The
basic design is a fast off-the-shelf (f/2.8 or better) fisheye lens
combined with some carefully-designed fixed lenses to produce telecentric
rays through a bank of high-quality narrow-band interference filters (e.g.,
2-nm bandwidth at half-max, OD5 in the stop-band, usually with other
requirements on film quality, etc; very custom). The filters are between 2
and 4 inches in diameter, so the telecentric requirement is pretty
stringent for many designs to keep the filter wavelength from shifting
across the image. The filters are often selectable by a motorized
filterwheel. Then, there are some more custom fixed optics that focus the
telecentric rays back onto the imaging detector. The precise choice of
detector depends a lot on the science you're trying to do. My experience
has been predominantly with consumer astronomical CCDs and CMOS detectors
from Atik, SBIG, and Andor (a little better than "consumer-grade"). I'll
see if I can find pictures of some of the instrumentation for you if you'd
like to geek out on it.
The emissions we're looking at usually pretty faint and require long
integration (exposure) times to overcome measurement noise. The 630-nm
"red line" emission comes from an excited state of oxygen that's observed
in both the aurora and the airglow. Airglow is a by-product of the plasma
process of recombination, which is the reverse of production (ionization),
which is what the Sun does to create the ionosphere in the first place.
Red airglow comes from just below the peak plasma density of the F2 region,
about 250 km up. Green airglow (557.7 nm) is a brighter oxygen emission
and comes from the E region, about 97 km altitude. If you've seen
astronomical photos of waves in the night sky, these are probably green
airglow. This is also the photochemistry as the green aurora, although the
driving process is the magnetosphere, not diurnal recombination.
I've been "inside the fence" at Haleakala. I was a grad student at the
time and my advisor dropped into my office one day and said, "How do you
feel about going to Hawaii?" I responded affirmatively. The following
day, he came in and said, "How's Monday?" My host/minder was an USAF
contractor who had been an MP in Bosnia. The instrumentation (two separate
cameras) resided in several "huts" that could only be accessed by passing
through secure areas. The big dial locks on the doors made an impression
for sure. I don't think there would have been much "talking your way in,"
at least on the Air Force side. Their telescope can do things that the one
on the astronomy side can't. It moved really fast when they demo'ed it for
me. Of course, the night sky was amazing, too, with the clouds below you.
Did that scratch the itch? Now I'm getting wanderlust...
73,
--Ethan, K8GU.
On Mon, Jun 29, 2020 at 7:00 PM Tom Holmes via mvus-list <
mvus-list@lists.febo.com> wrote:
Ethan...
Cool video, but don’t understand why the UFO's are moving but not the
stars 😉.
Can you talk more about the hardware you have to do this?
Have been to Haleakala a couple of times, but always had family so didn’t
make the effort to bluff my way into the observatory. Would have loved to
see it. I have been to Kitt's Peak in AZ, and to the VLA, both of which
quite fascinating, each in their own way.
Tom Holmes, N8ZM
-----Original Message-----
From: mvus-list mvus-list-bounces@lists.febo.com On Behalf Of Ethan
Miller K8GU via mvus-list
Sent: Monday, June 29, 2020 6:44 PM
To: Midwest VHF/UHF Society Mailing List mvus-list@lists.febo.com
Cc: Ethan Miller K8GU ethan@k8gu.com
Subject: Re: [mvus-list] Arecibo HF
Dana,
Cool. Yes, there's quite a bit of mutual coupling in this system!
I'm vaguely familiar with the source of the transmitters (I was
involved with putting a newer instrument at the location of the West
Coast counterpart), but have not gotten into the details of the feeds,
antennas, etc. It's neat to hear the backstory on the role that you
and Daun played!
Here is a link to a time-lapse movie taken at the Observatory (for
whatever reason, I can't lay my hands on data from the Culebra
instrument during heating right now). About 24 seconds into the
movie, you'll see a white spot in the center of the field of view
blinking ON and OFF. That's the HF.
http://k8gu.com/webpost/ao151109_6300.avi
http://k8gu.com/webpost/ao151109_6300.avi
I believe the Arecibo imager was only looking at the 630-nm emission
and my camera was configured for 557.7-nm, 589.3-nm, and OH broadband
in the near-IR. Because this is a filterwheel system, each additional
wavelength reduces temporal sampling. It becomes burdensome at the
four-minute exposures we were doing! In case you wondered, for some
reason, this imager is also out of focus. Mine was never that bad!
The Culebra site is quite good for the Caribbean, better than Arecibo,
but perhaps comparable to Bonaire, which is dry and not too overrun
with tourists and hotels. It is nothing like a number of other
optical sites where I've operated equipment, for example Cerro Tololo,
Chile, and Haleakala, Hawaii. I have not been to the new site that
they negotiated after the new management came in a couple of years
ago. I'll try to drag out some more heating imagery and see what I
have that I've never looked at. Believe it or not, my HF receiving
data from Culebra has been more interesting than the imagery so far.
We originally installed the imager to study a certain class of
traveling ionospheric disturbances that are pretty commonly observed
over Puerto Rico. There is a paper on this coming out in J. Geophys.
Res. soon, led by Pedrina Santos, of Arecibo.
The airport approach into CPX is pretty cool...going through that
little pass that's not-quite-aligned with the runway! My coworker and
I flew over on a Cape Air BN-2B Islander from SJU and had 4-5 Pelican
cases full of gear. The pilot very carefully balanced the plane
before we took off and I think we may have bumped another passenger.
That was a great trip.
73,
--Ethan, K8GU.
On Mon, Jun 29, 2020 at 5:42 PM Dana Whitlow via mvus-list
< mailto:mvus-list@lists.febo.com mvus-list@lists.febo.com> wrote:
What got me interested in "seeing" the light emission resulting from
Arecibo's HF system was in search of a better, more practical solution
problem of properly phasing the transmitters' outputs into their
in the array. I designed the multi-phase splitter for Arecibo while
there, and Daun pretty much built the whole thing hardware-wise. But
is that the dipoles talk to each other, and the driving impedance
dipole's feed point is not infinity, so radiation from each dipole
and phases of the currents in all the other dipoles, ad nauseum.
One option is careful system simulation, and I have put some effort
frankly it's not looking like a viable solution to me. Too many
guesses are involved. BTW, does anybody have a good Spice model for a
4CW150,000E power tetrode?
Another is direct measurement of the feed point complex currents with
coils (or similar sensors), but this is not trivial and would require
of significant funds in the sensors and in phase-matched cables running
the TX building. Nevertheless I suspect this is the best way.
Another, that is more economical, is to make all the transmission lines
integer number of half waves, and make the measurements at the TX end
cables. I worked out a way of doing the measurements with
of which sufficient extras came installed in the transmitters. I used
for trimming our feedlines to the same "length" (although they could
integer multiples of a half-wave), and it looked very promising. But
in actual operation requires building a bunch of additional
yet had the time or money to do so.
So, at present the technique used is to measure amplitude and phase of
wave (only) at the TX end of each line, basically by hand, and
transmitters' drive signals until we're happy with the results. This
working OK, but we don't know for sure, and it's a royal pain to do in
real problem is that this method does not really account for
dipoles, especially given that the transmitters' output are "power
impedance matched). BTW, does anybody have a good Spice model for a
The means for setting phases is via computer control of the stuff that
with a Python program written by another engineer (who has also left
But now, I can get to my other idea for optimizing phasing, which is to
emitted light in real time and crank on the "knobs" until the spot
most compact. It could even be done with a camera at a very remote
internet, thus allowing a camera location where the skies are really
Culebra site comes to mind for this.
On Sun, Jun 28, 2020 at 6:58 AM Ethan Miller K8GU via mvus-list <
Sorry I missed the MVUS showing of Arecibo photos. I had an HF
receiver and a relatively sensitive all-sky (fisheye) imager (the
imager is still there but operated by someone else now) in Culebra
a couple of years (for a different experiment) that was occasionally
repurposed for Arecibo HF experiments. It's pretty wild to see some
of the ionospheric structures they created with the HF system,
including airglow structures that were sub-visual magnitude blinking
on and off with the HF transmitter. Of course, at HAARP they've done
visual magnitude airglow, which does nothing to quell the conspiracy
I'm not a hard-core plasma physicist, but the stimulated RF emissions
from the Arecibo HF were also always interesting to see...the
high-power HF mode converts into plasma waves which interact with
other and some of them mode convert back into electromagnetic waves
different frequencies, shifted by "natural frequencies" (for example
the electron gyrofrequency) of the plasma. These are the types of
things that are theorized to be explanations for long-delayed echoes
(LDEs) and other radio oddities. I'll have to see if I have any data
floating around still that is clear and illustrative to a
technically-literate non-expert audience...
On Sun, Jun 28, 2020 at 1:56 AM Lenny via mvus-list
Just wondering if I can use the pictures and description in the Mt
VHF Radio Club ("The Packrats") newsletter. I'm sure the members
Please let me know either way.
--Lenny W2BVH (newsletter editor)
On 6/27/2020 4:28 PM, Daun Yeagley via mvus-list wrote:
It's "fun" trying to sort through all my pictures from Arecibo,
they are stored by date, and who knows what I was doing on a
Anyway, here are some pictures of the HF transmitters, and the
antennas in the bottom of the dish. For scale, look for the
that are standing in the opening in the middle. (that's where
hoist stuff up to the platform). Also, on the last one, if you
carefully you can see the cables that make up the secondary
Repair. Re-use. Re-purpose. Recycle.
Ethan,
What is the bandwidth of typical filters used in upper atmosphere
studies?
You've made a couple of references to long time exposures. Yet
watching the videos of Arecibo-driven light emission while I was
there gave me the distinct impression that this was normal video
at normal frame rates. Was that just wishful thinking on my part?
Note that I've not yet watched the video you attached- the only
PC I have that *may* be able to play AVI format is rather busy at the
moment doing other things.
Dana
On Mon, Jun 29, 2020 at 8:59 PM Ethan Miller K8GU via mvus-list <
mvus-list@lists.febo.com> wrote:
> Tom,
>
> Like "Fight Club," the first rule of UFOs is "don't talk about the UFOs."
>
> I don't currently have any equipment to do all-sky imaging. There are
> several commercial sources and the pricing is from ~$10K to ~$100K. The
> basic design is a fast off-the-shelf (f/2.8 or better) fisheye lens
> combined with some carefully-designed fixed lenses to produce telecentric
> rays through a bank of high-quality narrow-band interference filters (e.g.,
> 2-nm bandwidth at half-max, OD5 in the stop-band, usually with other
> requirements on film quality, etc; very custom). The filters are between 2
> and 4 inches in diameter, so the telecentric requirement is pretty
> stringent for many designs to keep the filter wavelength from shifting
> across the image. The filters are often selectable by a motorized
> filterwheel. Then, there are some more custom fixed optics that focus the
> telecentric rays back onto the imaging detector. The precise choice of
> detector depends a lot on the science you're trying to do. My experience
> has been predominantly with consumer astronomical CCDs and CMOS detectors
> from Atik, SBIG, and Andor (a little better than "consumer-grade"). I'll
> see if I can find pictures of some of the instrumentation for you if you'd
> like to geek out on it.
>
> The emissions we're looking at usually pretty faint and require long
> integration (exposure) times to overcome measurement noise. The 630-nm
> "red line" emission comes from an excited state of oxygen that's observed
> in both the aurora and the airglow. Airglow is a by-product of the plasma
> process of recombination, which is the reverse of production (ionization),
> which is what the Sun does to create the ionosphere in the first place.
> Red airglow comes from just below the peak plasma density of the F2 region,
> about 250 km up. Green airglow (557.7 nm) is a brighter oxygen emission
> and comes from the E region, about 97 km altitude. If you've seen
> astronomical photos of waves in the night sky, these are probably green
> airglow. This is also the photochemistry as the green aurora, although the
> driving process is the magnetosphere, not diurnal recombination.
>
> I've been "inside the fence" at Haleakala. I was a grad student at the
> time and my advisor dropped into my office one day and said, "How do you
> feel about going to Hawaii?" I responded affirmatively. The following
> day, he came in and said, "How's Monday?" My host/minder was an USAF
> contractor who had been an MP in Bosnia. The instrumentation (two separate
> cameras) resided in several "huts" that could only be accessed by passing
> through secure areas. The big dial locks on the doors made an impression
> for sure. I don't think there would have been much "talking your way in,"
> at least on the Air Force side. Their telescope can do things that the one
> on the astronomy side can't. It moved really fast when they demo'ed it for
> me. Of course, the night sky was amazing, too, with the clouds below you.
>
> Did that scratch the itch? Now I'm getting wanderlust...
>
> 73,
>
> --Ethan, K8GU.
>
>
>
> On Mon, Jun 29, 2020 at 7:00 PM Tom Holmes via mvus-list <
> mvus-list@lists.febo.com> wrote:
>
> > Ethan...
> >
> >
> >
> > Cool video, but don’t understand why the UFO's are moving but not the
> > stars 😉.
> >
> >
> >
> > Can you talk more about the hardware you have to do this?
> >
> >
> >
> > Have been to Haleakala a couple of times, but always had family so didn’t
> > make the effort to bluff my way into the observatory. Would have loved to
> > see it. I have been to Kitt's Peak in AZ, and to the VLA, both of which
> are
> > quite fascinating, each in their own way.
> >
> >
> >
> > Tom Holmes, N8ZM
> >
> >
> >
> > -----Original Message-----
> > From: mvus-list <mvus-list-bounces@lists.febo.com> On Behalf Of Ethan
> > Miller K8GU via mvus-list
> > Sent: Monday, June 29, 2020 6:44 PM
> > To: Midwest VHF/UHF Society Mailing List <mvus-list@lists.febo.com>
> > Cc: Ethan Miller K8GU <ethan@k8gu.com>
> > Subject: Re: [mvus-list] Arecibo HF
> >
> >
> >
> > Dana,
> >
> >
> >
> > Cool. Yes, there's quite a bit of mutual coupling in this system!
> >
> > I'm vaguely familiar with the source of the transmitters (I was
> >
> > involved with putting a newer instrument at the location of the West
> >
> > Coast counterpart), but have not gotten into the details of the feeds,
> >
> > antennas, etc. It's neat to hear the backstory on the role that you
> >
> > and Daun played!
> >
> >
> >
> > Here is a link to a time-lapse movie taken at the Observatory (for
> >
> > whatever reason, I can't lay my hands on data from the Culebra
> >
> > instrument during heating right now). About 24 seconds into the
> >
> > movie, you'll see a white spot in the center of the field of view
> >
> > blinking ON and OFF. That's the HF.
> >
> >
> >
> > <http://k8gu.com/webpost/ao151109_6300.avi>
> > http://k8gu.com/webpost/ao151109_6300.avi
> >
> >
> >
> > I believe the Arecibo imager was only looking at the 630-nm emission
> >
> > and my camera was configured for 557.7-nm, 589.3-nm, and OH broadband
> >
> > in the near-IR. Because this is a filterwheel system, each additional
> >
> > wavelength reduces temporal sampling. It becomes burdensome at the
> >
> > four-minute exposures we were doing! In case you wondered, for some
> >
> > reason, this imager is also out of focus. Mine was never that bad!
> >
> >
> >
> > The Culebra site is quite good for the Caribbean, better than Arecibo,
> >
> > but perhaps comparable to Bonaire, which is dry and not too overrun
> >
> > with tourists and hotels. It is nothing like a number of other
> >
> > optical sites where I've operated equipment, for example Cerro Tololo,
> >
> > Chile, and Haleakala, Hawaii. I have not been to the new site that
> >
> > they negotiated after the new management came in a couple of years
> >
> > ago. I'll try to drag out some more heating imagery and see what I
> >
> > have that I've never looked at. Believe it or not, my HF receiving
> >
> > data from Culebra has been more interesting than the imagery so far.
> >
> >
> >
> > We originally installed the imager to study a certain class of
> >
> > traveling ionospheric disturbances that are pretty commonly observed
> >
> > over Puerto Rico. There is a paper on this coming out in J. Geophys.
> >
> > Res. soon, led by Pedrina Santos, of Arecibo.
> >
> >
> >
> > The airport approach into CPX is pretty cool...going through that
> >
> > little pass that's not-quite-aligned with the runway! My coworker and
> >
> > I flew over on a Cape Air BN-2B Islander from SJU and had 4-5 Pelican
> >
> > cases full of gear. The pilot very carefully balanced the plane
> >
> > before we took off and I think we may have bumped another passenger.
> >
> > That was a great trip.
> >
> >
> >
> > 73,
> >
> >
> >
> > --Ethan, K8GU.
> >
> >
> >
> >
> >
> >
> >
> > On Mon, Jun 29, 2020 at 5:42 PM Dana Whitlow via mvus-list
> >
> > < <mailto:mvus-list@lists.febo.com> mvus-list@lists.febo.com> wrote:
> >
> > >
> >
> > > Ethan,
> >
> > >
> >
> > > What got me interested in "seeing" the light emission resulting from
> >
> > > operation of
> >
> > > Arecibo's HF system was in search of a better, more practical solution
> to
> >
> > > the
> >
> > > problem of properly phasing the transmitters' outputs into their
> > respective
> >
> > > dipoles
> >
> > > in the array. I designed the multi-phase splitter for Arecibo while
> > still
> >
> > > employed
> >
> > > there, and Daun pretty much built the whole thing hardware-wise. But
> > the
> >
> > > problem
> >
> > > is that the dipoles talk to each other, and the driving impedance
> > presented
> >
> > > to each
> >
> > > dipole's feed point is not infinity, so radiation from each dipole
> >
> > > affects the amplitudes
> >
> > > and phases of the currents in all the other dipoles, ad nauseum.
> >
> > >
> >
> > > One option is careful system simulation, and I have put some effort
> into
> >
> > > this, but
> >
> > > frankly it's not looking like a viable solution to me. Too many
> >
> > > imponderables and
> >
> > > guesses are involved. BTW, does anybody have a good Spice model for a
> >
> > > 4CW150,000E power tetrode?
> >
> > >
> >
> > > Another is direct measurement of the feed point complex currents with
> >
> > > Rogowski
> >
> > > coils (or similar sensors), but this is not trivial and would require
> the
> >
> > > expenditure
> >
> > > of significant funds in the sensors and in phase-matched cables running
> >
> > > back to
> >
> > > the TX building. Nevertheless I suspect this is the best way.
> >
> > >
> >
> > > Another, that is more economical, is to make all the transmission lines
> > an
> >
> > > exact
> >
> > > integer number of half waves, and make the measurements at the TX end
> of
> > the
> >
> > > cables. I worked out a way of doing the measurements with
> > dual-directional
> >
> > > couplers,
> >
> > > of which sufficient extras came installed in the transmitters. I used
> > this
> >
> > > basic technique
> >
> > > for trimming our feedlines to the same "length" (although they could
> > differ
> >
> > > in length by
> >
> > > integer multiples of a half-wave), and it looked very promising. But
> > using
> >
> > > the technique
> >
> > > in actual operation requires building a bunch of additional
> electronics,
> >
> > > and nobody has
> >
> > > yet had the time or money to do so.
> >
> > >
> >
> > > So, at present the technique used is to measure amplitude and phase of
> > the
> >
> > > *forward*
> >
> > > *wave* (only) at the TX end of each line, basically by hand, and
> >
> > > iteratively tweak on the
> >
> > > transmitters' drive signals until we're happy with the results. This
> >
> > > actually *seems* to be
> >
> > > working OK, but we don't know for sure, and it's a royal pain to do in
> > any
> >
> > > case. The
> >
> > > real problem is that this method does not really account for
> interactions
> >
> > > between the
> >
> > > dipoles, especially given that the transmitters' output are "power
> >
> > > matched", (not
> >
> > > impedance matched). BTW, does anybody have a good Spice model for a
> >
> > > 4CW150,000E
> >
> > > power tetrode?
> >
> > >
> >
> > > The means for setting phases is via computer control of the stuff that
> > Daun
> >
> > > put together,
> >
> > > with a Python program written by another engineer (who has also left
> the
> >
> > > observatory).
> >
> > >
> >
> > > But now, I can get to my other idea for optimizing phasing, which is to
> >
> > > view the spot of
> >
> > > emitted light in real time and crank on the "knobs" until the spot
> > becomes
> >
> > > brightest and
> >
> > > most compact. It could even be done with a camera at a very remote
> >
> > > location via the
> >
> > > internet, thus allowing a camera location where the skies are really
> > dark.
> >
> > > Naturally the
> >
> > > Culebra site comes to mind for this.
> >
> > >
> >
> > > Dana
> >
> > >
> >
> > >
> >
> > > On Sun, Jun 28, 2020 at 6:58 AM Ethan Miller K8GU via mvus-list <
> >
> > > <mailto:mvus-list@lists.febo.com> mvus-list@lists.febo.com> wrote:
> >
> > >
> >
> > > > Daun/Dana,
> >
> > > >
> >
> > > > Sorry I missed the MVUS showing of Arecibo photos. I had an HF
> >
> > > > receiver and a relatively sensitive all-sky (fisheye) imager (the
> >
> > > > imager is still there but operated by someone else now) in Culebra
> for
> >
> > > > a couple of years (for a different experiment) that was occasionally
> >
> > > > repurposed for Arecibo HF experiments. It's pretty wild to see some
> >
> > > > of the ionospheric structures they created with the HF system,
> >
> > > > including airglow structures that were sub-visual magnitude blinking
> >
> > > > on and off with the HF transmitter. Of course, at HAARP they've done
> >
> > > > visual magnitude airglow, which does nothing to quell the conspiracy
> >
> > > > theories!
> >
> > > >
> >
> > > > I'm not a hard-core plasma physicist, but the stimulated RF emissions
> >
> > > > from the Arecibo HF were also always interesting to see...the
> >
> > > > high-power HF mode converts into plasma waves which interact with
> each
> >
> > > > other and some of them mode convert back into electromagnetic waves
> at
> >
> > > > different frequencies, shifted by "natural frequencies" (for example
> >
> > > > the electron gyrofrequency) of the plasma. These are the types of
> >
> > > > things that are theorized to be explanations for long-delayed echoes
> >
> > > > (LDEs) and other radio oddities. I'll have to see if I have any data
> >
> > > > floating around still that is clear and illustrative to a
> >
> > > > technically-literate non-expert audience...
> >
> > > >
> >
> > > > 73,
> >
> > > >
> >
> > > > --Ethan, K8GU.
> >
> > > >
> >
> > > > On Sun, Jun 28, 2020 at 1:56 AM Lenny via mvus-list
> >
> > > > < <mailto:mvus-list@lists.febo.com> mvus-list@lists.febo.com> wrote:
> >
> > > > >
> >
> > > > > Hi Daun
> >
> > > > >
> >
> > > > > Just wondering if I can use the pictures and description in the Mt
> > Airy
> >
> > > > > VHF Radio Club ("The Packrats") newsletter. I'm sure the members
> > would
> >
> > > > > be interested.
> >
> > > > >
> >
> > > > > Please let me know either way.
> >
> > > > >
> >
> > > > > Tnx, 73 & stay safe,
> >
> > > > >
> >
> > > > > --Lenny W2BVH (newsletter editor)
> >
> > > > >
> >
> > > > >
> >
> > > > >
> >
> > > > > On 6/27/2020 4:28 PM, Daun Yeagley via mvus-list wrote:
> >
> > > > > > It's "fun" trying to sort through all my pictures from Arecibo,
> as
> >
> > > > > > they are stored by date, and who knows what I was doing on a
> >
> > > > > > particular day!
> >
> > > > > >
> >
> > > > > > Anyway, here are some pictures of the HF transmitters, and the
> >
> > > > > > antennas in the bottom of the dish. For scale, look for the
> guys
> >
> > > > > > that are standing in the opening in the middle. (that's where
> they
> >
> > > > > > hoist stuff up to the platform). Also, on the last one, if you
> > look
> >
> > > > > > carefully you can see the cables that make up the secondary
> > reflector.
> >
> > > > > >
> >
> > > > > > Daun
> >
> > > > > >
> >
> > > > > >
> >
> > > > > > _______________________________________________
> >
> > > > > > mvus-list mailing list
> >
> > > > > > <mailto:mvus-list@lists.febo.com> mvus-list@lists.febo.com
> >
> > > > > > <
> http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com>
> > http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
> >
> > > > > _______________________________________________
> >
> > > > > mvus-list mailing list
> >
> > > > > <mailto:mvus-list@lists.febo.com> mvus-list@lists.febo.com
> >
> > > > > <http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com>
> > http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
> >
> > > >
> >
> > > >
> >
> > > >
> >
> > > > --
> >
> > > > <http://www.k8gu.com/> http://www.k8gu.com/
> >
> > > > Repair. Re-use. Re-purpose. Recycle.
> >
> > > >
> >
> > > > _______________________________________________
> >
> > > > mvus-list mailing list
> >
> > > > <mailto:mvus-list@lists.febo.com> mvus-list@lists.febo.com
> >
> > > > <http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com>
> > http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
> >
> > > >
> >
> > > _______________________________________________
> >
> > > mvus-list mailing list
> >
> > > <mailto:mvus-list@lists.febo.com> mvus-list@lists.febo.com
> >
> > > <http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com>
> > http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
> >
> >
> >
> >
> >
> >
> >
> > --
> >
> > <http://www.k8gu.com/> http://www.k8gu.com/
> >
> > Repair. Re-use. Re-purpose. Recycle.
> >
> >
> >
> > _______________________________________________
> >
> > mvus-list mailing list
> >
> > <mailto:mvus-list@lists.febo.com> mvus-list@lists.febo.com
> >
> > <http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com>
> > http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
> >
> > _______________________________________________
> > mvus-list mailing list
> > mvus-list@lists.febo.com
> > http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
> >
>
>
> --
> http://www.k8gu.com/
> Repair. Re-use. Re-purpose. Recycle.
> _______________________________________________
> mvus-list mailing list
> mvus-list@lists.febo.com
> http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
>
DW
Dana Whitlow
Tue, Jun 30, 2020 2:21 AM
Tom,
Did "they" qualify that statement about "fastest moving dish on the planet"
with the size?
I feel pretty sure that there must be (smaller) radar dishes which can move
fast enough
to track low-flying aircraft as they pass overhead.
Dana
On Mon, Jun 29, 2020 at 9:10 PM Tom Holmes via mvus-list <
mvus-list@lists.febo.com> wrote:
Hi Ethan…
Very cool! It would be interesting to see more on it all. I’m not a
photographer type at all but it is interesting to see what is done
optically compared to at RF.
I once did a spectrum analyzer training class for the Navy in MD that was
dealing with dishes looking upwards. They were somewhat secretive about
what they were doing, so we settled on calling it radio astronomy. At one
point they showed me a 70’ dish that could go from horizon to horizon in
like 2 minutes. They claimed it was the fastest moving dish on the planet.
I’ve yet to find any stars or planets that move that quickly (wink-wink).
At least they didn’t have to shoot me when the class was over.
Tom Holmes, N8ZM
From: Ethan Miller K8GU ethan@k8gu.com
Sent: Monday, June 29, 2020 9:59 PM
To: Midwest VHF/UHF Society Mailing List mvus-list@lists.febo.com
Cc: Tom Holmes tholmes@woh.rr.com
Subject: Imagery (was Re: [mvus-list] Arecibo HF)
Tom,
Like "Fight Club," the first rule of UFOs is "don't talk about the UFOs."
I don't currently have any equipment to do all-sky imaging. There are
several commercial sources and the pricing is from ~$10K to ~$100K. The
basic design is a fast off-the-shelf (f/2.8 or better) fisheye lens
combined with some carefully-designed fixed lenses to produce telecentric
rays through a bank of high-quality narrow-band interference filters (e.g.,
2-nm bandwidth at half-max, OD5 in the stop-band, usually with other
requirements on film quality, etc; very custom). The filters are between 2
and 4 inches in diameter, so the telecentric requirement is pretty
stringent for many designs to keep the filter wavelength from shifting
across the image. The filters are often selectable by a motorized
filterwheel. Then, there are some more custom fixed optics that focus the
telecentric rays back onto the imaging detector. The precise choice of
detector depends a lot on the science you're trying to do. My experience
has been predominantly with consumer astronomical CCDs and CMOS detectors
from Atik, SBIG, and Andor (a little better than "consumer-grade"). I'll
see if I can find pictures of some of the instrumentation for you if you'd
like to geek out on it.
The emissions we're looking at usually pretty faint and require long
integration (exposure) times to overcome measurement noise. The 630-nm
"red line" emission comes from an excited state of oxygen that's observed
in both the aurora and the airglow. Airglow is a by-product of the plasma
process of recombination, which is the reverse of production (ionization),
which is what the Sun does to create the ionosphere in the first place.
Red airglow comes from just below the peak plasma density of the F2 region,
about 250 km up. Green airglow (557.7 nm) is a brighter oxygen emission
and comes from the E region, about 97 km altitude. If you've seen
astronomical photos of waves in the night sky, these are probably green
airglow. This is also the photochemistry as the green aurora, although the
driving process is the magnetosphere, not diurnal recombination.
I've been "inside the fence" at Haleakala. I was a grad student at the
time and my advisor dropped into my office one day and said, "How do you
feel about going to Hawaii?" I responded affirmatively. The following
day, he came in and said, "How's Monday?" My host/minder was an USAF
contractor who had been an MP in Bosnia. The instrumentation (two separate
cameras) resided in several "huts" that could only be accessed by passing
through secure areas. The big dial locks on the doors made an impression
for sure. I don't think there would have been much "talking your way in,"
at least on the Air Force side. Their telescope can do things that the one
on the astronomy side can't. It moved really fast when they demo'ed it for
me. Of course, the night sky was amazing, too, with the clouds below you.
Did that scratch the itch? Now I'm getting wanderlust...
73,
--Ethan, K8GU.
On Mon, Jun 29, 2020 at 7:00 PM Tom Holmes via mvus-list <
mvus-list@lists.febo.com mailto:mvus-list@lists.febo.com > wrote:
Ethan...
Cool video, but don’t understand why the UFO's are moving but not the
stars 😉.
Can you talk more about the hardware you have to do this?
Have been to Haleakala a couple of times, but always had family so didn’t
make the effort to bluff my way into the observatory. Would have loved to
see it. I have been to Kitt's Peak in AZ, and to the VLA, both of which are
quite fascinating, each in their own way.
Tom Holmes, N8ZM
-----Original Message-----
From: mvus-list <mvus-list-bounces@lists.febo.com <mailto:
mvus-list-bounces@lists.febo.com> > On Behalf Of Ethan Miller K8GU via
mvus-list
Sent: Monday, June 29, 2020 6:44 PM
To: Midwest VHF/UHF Society Mailing List <mvus-list@lists.febo.com
mailto:mvus-list@lists.febo.com >
Cc: Ethan Miller K8GU <ethan@k8gu.com mailto:ethan@k8gu.com >
Subject: Re: [mvus-list] Arecibo HF
Dana,
Cool. Yes, there's quite a bit of mutual coupling in this system!
I'm vaguely familiar with the source of the transmitters (I was
involved with putting a newer instrument at the location of the West
Coast counterpart), but have not gotten into the details of the feeds,
antennas, etc. It's neat to hear the backstory on the role that you
and Daun played!
Here is a link to a time-lapse movie taken at the Observatory (for
whatever reason, I can't lay my hands on data from the Culebra
instrument during heating right now). About 24 seconds into the
movie, you'll see a white spot in the center of the field of view
blinking ON and OFF. That's the HF.
http://k8gu.com/webpost/ao151109_6300.avi
http://k8gu.com/webpost/ao151109_6300.avi
I believe the Arecibo imager was only looking at the 630-nm emission
and my camera was configured for 557.7-nm, 589.3-nm, and OH broadband
in the near-IR. Because this is a filterwheel system, each additional
wavelength reduces temporal sampling. It becomes burdensome at the
four-minute exposures we were doing! In case you wondered, for some
reason, this imager is also out of focus. Mine was never that bad!
The Culebra site is quite good for the Caribbean, better than Arecibo,
but perhaps comparable to Bonaire, which is dry and not too overrun
with tourists and hotels. It is nothing like a number of other
optical sites where I've operated equipment, for example Cerro Tololo,
Chile, and Haleakala, Hawaii. I have not been to the new site that
they negotiated after the new management came in a couple of years
ago. I'll try to drag out some more heating imagery and see what I
have that I've never looked at. Believe it or not, my HF receiving
data from Culebra has been more interesting than the imagery so far.
We originally installed the imager to study a certain class of
traveling ionospheric disturbances that are pretty commonly observed
over Puerto Rico. There is a paper on this coming out in J. Geophys.
Res. soon, led by Pedrina Santos, of Arecibo.
The airport approach into CPX is pretty cool...going through that
little pass that's not-quite-aligned with the runway! My coworker and
I flew over on a Cape Air BN-2B Islander from SJU and had 4-5 Pelican
cases full of gear. The pilot very carefully balanced the plane
before we took off and I think we may have bumped another passenger.
That was a great trip.
73,
--Ethan, K8GU.
On Mon, Jun 29, 2020 at 5:42 PM Dana Whitlow via mvus-list
< <mailto:mvus-list@lists.febo.com mailto:mvus-list@lists.febo.com >
mvus-list@lists.febo.com mailto:mvus-list@lists.febo.com > wrote:
What got me interested in "seeing" the light emission resulting from
Arecibo's HF system was in search of a better, more practical solution to
problem of properly phasing the transmitters' outputs into their
in the array. I designed the multi-phase splitter for Arecibo while
there, and Daun pretty much built the whole thing hardware-wise. But
is that the dipoles talk to each other, and the driving impedance
dipole's feed point is not infinity, so radiation from each dipole
and phases of the currents in all the other dipoles, ad nauseum.
One option is careful system simulation, and I have put some effort into
frankly it's not looking like a viable solution to me. Too many
guesses are involved. BTW, does anybody have a good Spice model for a
4CW150,000E power tetrode?
Another is direct measurement of the feed point complex currents with
coils (or similar sensors), but this is not trivial and would require the
of significant funds in the sensors and in phase-matched cables running
the TX building. Nevertheless I suspect this is the best way.
Another, that is more economical, is to make all the transmission lines
integer number of half waves, and make the measurements at the TX end of
cables. I worked out a way of doing the measurements with
of which sufficient extras came installed in the transmitters. I used
for trimming our feedlines to the same "length" (although they could
integer multiples of a half-wave), and it looked very promising. But
in actual operation requires building a bunch of additional electronics,
yet had the time or money to do so.
So, at present the technique used is to measure amplitude and phase of
wave (only) at the TX end of each line, basically by hand, and
transmitters' drive signals until we're happy with the results. This
working OK, but we don't know for sure, and it's a royal pain to do in
real problem is that this method does not really account for interactions
dipoles, especially given that the transmitters' output are "power
impedance matched). BTW, does anybody have a good Spice model for a
The means for setting phases is via computer control of the stuff that
with a Python program written by another engineer (who has also left the
But now, I can get to my other idea for optimizing phasing, which is to
emitted light in real time and crank on the "knobs" until the spot
most compact. It could even be done with a camera at a very remote
internet, thus allowing a camera location where the skies are really
Culebra site comes to mind for this.
On Sun, Jun 28, 2020 at 6:58 AM Ethan Miller K8GU via mvus-list <
Sorry I missed the MVUS showing of Arecibo photos. I had an HF
receiver and a relatively sensitive all-sky (fisheye) imager (the
imager is still there but operated by someone else now) in Culebra for
a couple of years (for a different experiment) that was occasionally
repurposed for Arecibo HF experiments. It's pretty wild to see some
of the ionospheric structures they created with the HF system,
including airglow structures that were sub-visual magnitude blinking
on and off with the HF transmitter. Of course, at HAARP they've done
visual magnitude airglow, which does nothing to quell the conspiracy
I'm not a hard-core plasma physicist, but the stimulated RF emissions
from the Arecibo HF were also always interesting to see...the
high-power HF mode converts into plasma waves which interact with each
other and some of them mode convert back into electromagnetic waves at
different frequencies, shifted by "natural frequencies" (for example
the electron gyrofrequency) of the plasma. These are the types of
things that are theorized to be explanations for long-delayed echoes
(LDEs) and other radio oddities. I'll have to see if I have any data
floating around still that is clear and illustrative to a
technically-literate non-expert audience...
On Sun, Jun 28, 2020 at 1:56 AM Lenny via mvus-list
Just wondering if I can use the pictures and description in the Mt
VHF Radio Club ("The Packrats") newsletter. I'm sure the members
Please let me know either way.
--Lenny W2BVH (newsletter editor)
On 6/27/2020 4:28 PM, Daun Yeagley via mvus-list wrote:
It's "fun" trying to sort through all my pictures from Arecibo, as
they are stored by date, and who knows what I was doing on a
Anyway, here are some pictures of the HF transmitters, and the
antennas in the bottom of the dish. For scale, look for the guys
that are standing in the opening in the middle. (that's where they
hoist stuff up to the platform). Also, on the last one, if you
carefully you can see the cables that make up the secondary
Repair. Re-use. Re-purpose. Recycle.
Tom,
Did "they" qualify that statement about "fastest moving dish on the planet"
with the size?
I feel pretty sure that there must be (smaller) radar dishes which can move
fast enough
to track low-flying aircraft as they pass overhead.
Dana
On Mon, Jun 29, 2020 at 9:10 PM Tom Holmes via mvus-list <
mvus-list@lists.febo.com> wrote:
> Hi Ethan…
>
>
>
> Very cool! It would be interesting to see more on it all. I’m not a
> photographer type at all but it is interesting to see what is done
> optically compared to at RF.
>
>
>
> I once did a spectrum analyzer training class for the Navy in MD that was
> dealing with dishes looking upwards. They were somewhat secretive about
> what they were doing, so we settled on calling it radio astronomy. At one
> point they showed me a 70’ dish that could go from horizon to horizon in
> like 2 minutes. They claimed it was the fastest moving dish on the planet.
> I’ve yet to find any stars or planets that move that quickly (wink-wink).
> At least they didn’t have to shoot me when the class was over.
>
>
>
> Tom Holmes, N8ZM
>
>
>
> From: Ethan Miller K8GU <ethan@k8gu.com>
> Sent: Monday, June 29, 2020 9:59 PM
> To: Midwest VHF/UHF Society Mailing List <mvus-list@lists.febo.com>
> Cc: Tom Holmes <tholmes@woh.rr.com>
> Subject: Imagery (was Re: [mvus-list] Arecibo HF)
>
>
>
> Tom,
>
>
>
> Like "Fight Club," the first rule of UFOs is "don't talk about the UFOs."
>
>
>
> I don't currently have any equipment to do all-sky imaging. There are
> several commercial sources and the pricing is from ~$10K to ~$100K. The
> basic design is a fast off-the-shelf (f/2.8 or better) fisheye lens
> combined with some carefully-designed fixed lenses to produce telecentric
> rays through a bank of high-quality narrow-band interference filters (e.g.,
> 2-nm bandwidth at half-max, OD5 in the stop-band, usually with other
> requirements on film quality, etc; very custom). The filters are between 2
> and 4 inches in diameter, so the telecentric requirement is pretty
> stringent for many designs to keep the filter wavelength from shifting
> across the image. The filters are often selectable by a motorized
> filterwheel. Then, there are some more custom fixed optics that focus the
> telecentric rays back onto the imaging detector. The precise choice of
> detector depends a lot on the science you're trying to do. My experience
> has been predominantly with consumer astronomical CCDs and CMOS detectors
> from Atik, SBIG, and Andor (a little better than "consumer-grade"). I'll
> see if I can find pictures of some of the instrumentation for you if you'd
> like to geek out on it.
>
>
>
> The emissions we're looking at usually pretty faint and require long
> integration (exposure) times to overcome measurement noise. The 630-nm
> "red line" emission comes from an excited state of oxygen that's observed
> in both the aurora and the airglow. Airglow is a by-product of the plasma
> process of recombination, which is the reverse of production (ionization),
> which is what the Sun does to create the ionosphere in the first place.
> Red airglow comes from just below the peak plasma density of the F2 region,
> about 250 km up. Green airglow (557.7 nm) is a brighter oxygen emission
> and comes from the E region, about 97 km altitude. If you've seen
> astronomical photos of waves in the night sky, these are probably green
> airglow. This is also the photochemistry as the green aurora, although the
> driving process is the magnetosphere, not diurnal recombination.
>
>
>
> I've been "inside the fence" at Haleakala. I was a grad student at the
> time and my advisor dropped into my office one day and said, "How do you
> feel about going to Hawaii?" I responded affirmatively. The following
> day, he came in and said, "How's Monday?" My host/minder was an USAF
> contractor who had been an MP in Bosnia. The instrumentation (two separate
> cameras) resided in several "huts" that could only be accessed by passing
> through secure areas. The big dial locks on the doors made an impression
> for sure. I don't think there would have been much "talking your way in,"
> at least on the Air Force side. Their telescope can do things that the one
> on the astronomy side can't. It moved really fast when they demo'ed it for
> me. Of course, the night sky was amazing, too, with the clouds below you.
>
>
>
> Did that scratch the itch? Now I'm getting wanderlust...
>
>
>
> 73,
>
>
>
> --Ethan, K8GU.
>
>
>
>
>
>
>
> On Mon, Jun 29, 2020 at 7:00 PM Tom Holmes via mvus-list <
> mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> > wrote:
>
> Ethan...
>
>
>
> Cool video, but don’t understand why the UFO's are moving but not the
> stars 😉.
>
>
>
> Can you talk more about the hardware you have to do this?
>
>
>
> Have been to Haleakala a couple of times, but always had family so didn’t
> make the effort to bluff my way into the observatory. Would have loved to
> see it. I have been to Kitt's Peak in AZ, and to the VLA, both of which are
> quite fascinating, each in their own way.
>
>
>
> Tom Holmes, N8ZM
>
>
>
> -----Original Message-----
> From: mvus-list <mvus-list-bounces@lists.febo.com <mailto:
> mvus-list-bounces@lists.febo.com> > On Behalf Of Ethan Miller K8GU via
> mvus-list
> Sent: Monday, June 29, 2020 6:44 PM
> To: Midwest VHF/UHF Society Mailing List <mvus-list@lists.febo.com
> <mailto:mvus-list@lists.febo.com> >
> Cc: Ethan Miller K8GU <ethan@k8gu.com <mailto:ethan@k8gu.com> >
> Subject: Re: [mvus-list] Arecibo HF
>
>
>
> Dana,
>
>
>
> Cool. Yes, there's quite a bit of mutual coupling in this system!
>
> I'm vaguely familiar with the source of the transmitters (I was
>
> involved with putting a newer instrument at the location of the West
>
> Coast counterpart), but have not gotten into the details of the feeds,
>
> antennas, etc. It's neat to hear the backstory on the role that you
>
> and Daun played!
>
>
>
> Here is a link to a time-lapse movie taken at the Observatory (for
>
> whatever reason, I can't lay my hands on data from the Culebra
>
> instrument during heating right now). About 24 seconds into the
>
> movie, you'll see a white spot in the center of the field of view
>
> blinking ON and OFF. That's the HF.
>
>
>
> <http://k8gu.com/webpost/ao151109_6300.avi>
> http://k8gu.com/webpost/ao151109_6300.avi
>
>
>
> I believe the Arecibo imager was only looking at the 630-nm emission
>
> and my camera was configured for 557.7-nm, 589.3-nm, and OH broadband
>
> in the near-IR. Because this is a filterwheel system, each additional
>
> wavelength reduces temporal sampling. It becomes burdensome at the
>
> four-minute exposures we were doing! In case you wondered, for some
>
> reason, this imager is also out of focus. Mine was never that bad!
>
>
>
> The Culebra site is quite good for the Caribbean, better than Arecibo,
>
> but perhaps comparable to Bonaire, which is dry and not too overrun
>
> with tourists and hotels. It is nothing like a number of other
>
> optical sites where I've operated equipment, for example Cerro Tololo,
>
> Chile, and Haleakala, Hawaii. I have not been to the new site that
>
> they negotiated after the new management came in a couple of years
>
> ago. I'll try to drag out some more heating imagery and see what I
>
> have that I've never looked at. Believe it or not, my HF receiving
>
> data from Culebra has been more interesting than the imagery so far.
>
>
>
> We originally installed the imager to study a certain class of
>
> traveling ionospheric disturbances that are pretty commonly observed
>
> over Puerto Rico. There is a paper on this coming out in J. Geophys.
>
> Res. soon, led by Pedrina Santos, of Arecibo.
>
>
>
> The airport approach into CPX is pretty cool...going through that
>
> little pass that's not-quite-aligned with the runway! My coworker and
>
> I flew over on a Cape Air BN-2B Islander from SJU and had 4-5 Pelican
>
> cases full of gear. The pilot very carefully balanced the plane
>
> before we took off and I think we may have bumped another passenger.
>
> That was a great trip.
>
>
>
> 73,
>
>
>
> --Ethan, K8GU.
>
>
>
>
>
>
>
> On Mon, Jun 29, 2020 at 5:42 PM Dana Whitlow via mvus-list
>
> < <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> >
> mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> > wrote:
>
> >
>
> > Ethan,
>
> >
>
> > What got me interested in "seeing" the light emission resulting from
>
> > operation of
>
> > Arecibo's HF system was in search of a better, more practical solution to
>
> > the
>
> > problem of properly phasing the transmitters' outputs into their
> respective
>
> > dipoles
>
> > in the array. I designed the multi-phase splitter for Arecibo while
> still
>
> > employed
>
> > there, and Daun pretty much built the whole thing hardware-wise. But
> the
>
> > problem
>
> > is that the dipoles talk to each other, and the driving impedance
> presented
>
> > to each
>
> > dipole's feed point is not infinity, so radiation from each dipole
>
> > affects the amplitudes
>
> > and phases of the currents in all the other dipoles, ad nauseum.
>
> >
>
> > One option is careful system simulation, and I have put some effort into
>
> > this, but
>
> > frankly it's not looking like a viable solution to me. Too many
>
> > imponderables and
>
> > guesses are involved. BTW, does anybody have a good Spice model for a
>
> > 4CW150,000E power tetrode?
>
> >
>
> > Another is direct measurement of the feed point complex currents with
>
> > Rogowski
>
> > coils (or similar sensors), but this is not trivial and would require the
>
> > expenditure
>
> > of significant funds in the sensors and in phase-matched cables running
>
> > back to
>
> > the TX building. Nevertheless I suspect this is the best way.
>
> >
>
> > Another, that is more economical, is to make all the transmission lines
> an
>
> > exact
>
> > integer number of half waves, and make the measurements at the TX end of
> the
>
> > cables. I worked out a way of doing the measurements with
> dual-directional
>
> > couplers,
>
> > of which sufficient extras came installed in the transmitters. I used
> this
>
> > basic technique
>
> > for trimming our feedlines to the same "length" (although they could
> differ
>
> > in length by
>
> > integer multiples of a half-wave), and it looked very promising. But
> using
>
> > the technique
>
> > in actual operation requires building a bunch of additional electronics,
>
> > and nobody has
>
> > yet had the time or money to do so.
>
> >
>
> > So, at present the technique used is to measure amplitude and phase of
> the
>
> > *forward*
>
> > *wave* (only) at the TX end of each line, basically by hand, and
>
> > iteratively tweak on the
>
> > transmitters' drive signals until we're happy with the results. This
>
> > actually *seems* to be
>
> > working OK, but we don't know for sure, and it's a royal pain to do in
> any
>
> > case. The
>
> > real problem is that this method does not really account for interactions
>
> > between the
>
> > dipoles, especially given that the transmitters' output are "power
>
> > matched", (not
>
> > impedance matched). BTW, does anybody have a good Spice model for a
>
> > 4CW150,000E
>
> > power tetrode?
>
> >
>
> > The means for setting phases is via computer control of the stuff that
> Daun
>
> > put together,
>
> > with a Python program written by another engineer (who has also left the
>
> > observatory).
>
> >
>
> > But now, I can get to my other idea for optimizing phasing, which is to
>
> > view the spot of
>
> > emitted light in real time and crank on the "knobs" until the spot
> becomes
>
> > brightest and
>
> > most compact. It could even be done with a camera at a very remote
>
> > location via the
>
> > internet, thus allowing a camera location where the skies are really
> dark.
>
> > Naturally the
>
> > Culebra site comes to mind for this.
>
> >
>
> > Dana
>
> >
>
> >
>
> > On Sun, Jun 28, 2020 at 6:58 AM Ethan Miller K8GU via mvus-list <
>
> > <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> >
> mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> > wrote:
>
> >
>
> > > Daun/Dana,
>
> > >
>
> > > Sorry I missed the MVUS showing of Arecibo photos. I had an HF
>
> > > receiver and a relatively sensitive all-sky (fisheye) imager (the
>
> > > imager is still there but operated by someone else now) in Culebra for
>
> > > a couple of years (for a different experiment) that was occasionally
>
> > > repurposed for Arecibo HF experiments. It's pretty wild to see some
>
> > > of the ionospheric structures they created with the HF system,
>
> > > including airglow structures that were sub-visual magnitude blinking
>
> > > on and off with the HF transmitter. Of course, at HAARP they've done
>
> > > visual magnitude airglow, which does nothing to quell the conspiracy
>
> > > theories!
>
> > >
>
> > > I'm not a hard-core plasma physicist, but the stimulated RF emissions
>
> > > from the Arecibo HF were also always interesting to see...the
>
> > > high-power HF mode converts into plasma waves which interact with each
>
> > > other and some of them mode convert back into electromagnetic waves at
>
> > > different frequencies, shifted by "natural frequencies" (for example
>
> > > the electron gyrofrequency) of the plasma. These are the types of
>
> > > things that are theorized to be explanations for long-delayed echoes
>
> > > (LDEs) and other radio oddities. I'll have to see if I have any data
>
> > > floating around still that is clear and illustrative to a
>
> > > technically-literate non-expert audience...
>
> > >
>
> > > 73,
>
> > >
>
> > > --Ethan, K8GU.
>
> > >
>
> > > On Sun, Jun 28, 2020 at 1:56 AM Lenny via mvus-list
>
> > > < <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
> > mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> > wrote:
>
> > > >
>
> > > > Hi Daun
>
> > > >
>
> > > > Just wondering if I can use the pictures and description in the Mt
> Airy
>
> > > > VHF Radio Club ("The Packrats") newsletter. I'm sure the members
> would
>
> > > > be interested.
>
> > > >
>
> > > > Please let me know either way.
>
> > > >
>
> > > > Tnx, 73 & stay safe,
>
> > > >
>
> > > > --Lenny W2BVH (newsletter editor)
>
> > > >
>
> > > >
>
> > > >
>
> > > > On 6/27/2020 4:28 PM, Daun Yeagley via mvus-list wrote:
>
> > > > > It's "fun" trying to sort through all my pictures from Arecibo, as
>
> > > > > they are stored by date, and who knows what I was doing on a
>
> > > > > particular day!
>
> > > > >
>
> > > > > Anyway, here are some pictures of the HF transmitters, and the
>
> > > > > antennas in the bottom of the dish. For scale, look for the guys
>
> > > > > that are standing in the opening in the middle. (that's where they
>
> > > > > hoist stuff up to the platform). Also, on the last one, if you
> look
>
> > > > > carefully you can see the cables that make up the secondary
> reflector.
>
> > > > >
>
> > > > > Daun
>
> > > > >
>
> > > > >
>
> > > > > _______________________________________________
>
> > > > > mvus-list mailing list
>
> > > > > <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
> > mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
>
> > > > > <http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com>
> http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
>
> > > > _______________________________________________
>
> > > > mvus-list mailing list
>
> > > > <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
> > mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
>
> > > > <http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com>
> http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
>
> > >
>
> > >
>
> > >
>
> > > --
>
> > > <http://www.k8gu.com/> http://www.k8gu.com/
>
> > > Repair. Re-use. Re-purpose. Recycle.
>
> > >
>
> > > _______________________________________________
>
> > > mvus-list mailing list
>
> > > <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> >
> mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
>
> > > <http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com>
> http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
>
> > >
>
> > _______________________________________________
>
> > mvus-list mailing list
>
> > <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> >
> mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
>
> > <http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com>
> http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
>
>
>
>
>
>
>
> --
>
> <http://www.k8gu.com/> http://www.k8gu.com/
>
> Repair. Re-use. Re-purpose. Recycle.
>
>
>
> _______________________________________________
>
> mvus-list mailing list
>
> <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> >
> mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
>
> <http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com>
> http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
>
> _______________________________________________
> mvus-list mailing list
> mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
> http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
>
>
>
> --
>
> http://www.k8gu.com/
> Repair. Re-use. Re-purpose. Recycle.
>
> _______________________________________________
> mvus-list mailing list
> mvus-list@lists.febo.com
> http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
>
DS
Dave Sublette
Tue, Jun 30, 2020 2:23 AM
Altair could move their 150 ft dish at 10 degrees per second!
K4TO
On Mon, Jun 29, 2020 at 10:22 PM Dana Whitlow via mvus-list <
mvus-list@lists.febo.com> wrote:
Tom,
Did "they" qualify that statement about "fastest moving dish on the planet"
with the size?
I feel pretty sure that there must be (smaller) radar dishes which can move
fast enough
to track low-flying aircraft as they pass overhead.
Dana
On Mon, Jun 29, 2020 at 9:10 PM Tom Holmes via mvus-list <
mvus-list@lists.febo.com> wrote:
Hi Ethan…
Very cool! It would be interesting to see more on it all. I’m not a
photographer type at all but it is interesting to see what is done
optically compared to at RF.
I once did a spectrum analyzer training class for the Navy in MD that was
dealing with dishes looking upwards. They were somewhat secretive about
what they were doing, so we settled on calling it radio astronomy. At one
point they showed me a 70’ dish that could go from horizon to horizon in
like 2 minutes. They claimed it was the fastest moving dish on the
I’ve yet to find any stars or planets that move that quickly (wink-wink).
At least they didn’t have to shoot me when the class was over.
Tom Holmes, N8ZM
From: Ethan Miller K8GU ethan@k8gu.com
Sent: Monday, June 29, 2020 9:59 PM
To: Midwest VHF/UHF Society Mailing List mvus-list@lists.febo.com
Cc: Tom Holmes tholmes@woh.rr.com
Subject: Imagery (was Re: [mvus-list] Arecibo HF)
Tom,
Like "Fight Club," the first rule of UFOs is "don't talk about the UFOs."
I don't currently have any equipment to do all-sky imaging. There are
several commercial sources and the pricing is from ~$10K to ~$100K. The
basic design is a fast off-the-shelf (f/2.8 or better) fisheye lens
combined with some carefully-designed fixed lenses to produce telecentric
rays through a bank of high-quality narrow-band interference filters
2-nm bandwidth at half-max, OD5 in the stop-band, usually with other
requirements on film quality, etc; very custom). The filters are
and 4 inches in diameter, so the telecentric requirement is pretty
stringent for many designs to keep the filter wavelength from shifting
across the image. The filters are often selectable by a motorized
filterwheel. Then, there are some more custom fixed optics that focus
telecentric rays back onto the imaging detector. The precise choice of
detector depends a lot on the science you're trying to do. My experience
has been predominantly with consumer astronomical CCDs and CMOS detectors
from Atik, SBIG, and Andor (a little better than "consumer-grade"). I'll
see if I can find pictures of some of the instrumentation for you if
like to geek out on it.
The emissions we're looking at usually pretty faint and require long
integration (exposure) times to overcome measurement noise. The 630-nm
"red line" emission comes from an excited state of oxygen that's observed
in both the aurora and the airglow. Airglow is a by-product of the
process of recombination, which is the reverse of production
which is what the Sun does to create the ionosphere in the first place.
Red airglow comes from just below the peak plasma density of the F2
about 250 km up. Green airglow (557.7 nm) is a brighter oxygen emission
and comes from the E region, about 97 km altitude. If you've seen
astronomical photos of waves in the night sky, these are probably green
airglow. This is also the photochemistry as the green aurora, although
driving process is the magnetosphere, not diurnal recombination.
I've been "inside the fence" at Haleakala. I was a grad student at the
time and my advisor dropped into my office one day and said, "How do you
feel about going to Hawaii?" I responded affirmatively. The following
day, he came in and said, "How's Monday?" My host/minder was an USAF
contractor who had been an MP in Bosnia. The instrumentation (two
cameras) resided in several "huts" that could only be accessed by passing
through secure areas. The big dial locks on the doors made an impression
for sure. I don't think there would have been much "talking your way
at least on the Air Force side. Their telescope can do things that the
on the astronomy side can't. It moved really fast when they demo'ed it
me. Of course, the night sky was amazing, too, with the clouds below
Did that scratch the itch? Now I'm getting wanderlust...
73,
--Ethan, K8GU.
On Mon, Jun 29, 2020 at 7:00 PM Tom Holmes via mvus-list <
mvus-list@lists.febo.com mailto:mvus-list@lists.febo.com > wrote:
Ethan...
Cool video, but don’t understand why the UFO's are moving but not the
stars 😉.
Can you talk more about the hardware you have to do this?
Have been to Haleakala a couple of times, but always had family so didn’t
make the effort to bluff my way into the observatory. Would have loved to
see it. I have been to Kitt's Peak in AZ, and to the VLA, both of which
quite fascinating, each in their own way.
Tom Holmes, N8ZM
-----Original Message-----
From: mvus-list <mvus-list-bounces@lists.febo.com <mailto:
mvus-list-bounces@lists.febo.com> > On Behalf Of Ethan Miller K8GU via
mvus-list
Sent: Monday, June 29, 2020 6:44 PM
To: Midwest VHF/UHF Society Mailing List <mvus-list@lists.febo.com
mailto:mvus-list@lists.febo.com >
Cc: Ethan Miller K8GU <ethan@k8gu.com mailto:ethan@k8gu.com >
Subject: Re: [mvus-list] Arecibo HF
Dana,
Cool. Yes, there's quite a bit of mutual coupling in this system!
I'm vaguely familiar with the source of the transmitters (I was
involved with putting a newer instrument at the location of the West
Coast counterpart), but have not gotten into the details of the feeds,
antennas, etc. It's neat to hear the backstory on the role that you
and Daun played!
Here is a link to a time-lapse movie taken at the Observatory (for
whatever reason, I can't lay my hands on data from the Culebra
instrument during heating right now). About 24 seconds into the
movie, you'll see a white spot in the center of the field of view
blinking ON and OFF. That's the HF.
http://k8gu.com/webpost/ao151109_6300.avi
http://k8gu.com/webpost/ao151109_6300.avi
I believe the Arecibo imager was only looking at the 630-nm emission
and my camera was configured for 557.7-nm, 589.3-nm, and OH broadband
in the near-IR. Because this is a filterwheel system, each additional
wavelength reduces temporal sampling. It becomes burdensome at the
four-minute exposures we were doing! In case you wondered, for some
reason, this imager is also out of focus. Mine was never that bad!
The Culebra site is quite good for the Caribbean, better than Arecibo,
but perhaps comparable to Bonaire, which is dry and not too overrun
with tourists and hotels. It is nothing like a number of other
optical sites where I've operated equipment, for example Cerro Tololo,
Chile, and Haleakala, Hawaii. I have not been to the new site that
they negotiated after the new management came in a couple of years
ago. I'll try to drag out some more heating imagery and see what I
have that I've never looked at. Believe it or not, my HF receiving
data from Culebra has been more interesting than the imagery so far.
We originally installed the imager to study a certain class of
traveling ionospheric disturbances that are pretty commonly observed
over Puerto Rico. There is a paper on this coming out in J. Geophys.
Res. soon, led by Pedrina Santos, of Arecibo.
The airport approach into CPX is pretty cool...going through that
little pass that's not-quite-aligned with the runway! My coworker and
I flew over on a Cape Air BN-2B Islander from SJU and had 4-5 Pelican
cases full of gear. The pilot very carefully balanced the plane
before we took off and I think we may have bumped another passenger.
That was a great trip.
73,
--Ethan, K8GU.
On Mon, Jun 29, 2020 at 5:42 PM Dana Whitlow via mvus-list
< <mailto:mvus-list@lists.febo.com mailto:mvus-list@lists.febo.com >
mvus-list@lists.febo.com mailto:mvus-list@lists.febo.com > wrote:
What got me interested in "seeing" the light emission resulting from
Arecibo's HF system was in search of a better, more practical solution
problem of properly phasing the transmitters' outputs into their
in the array. I designed the multi-phase splitter for Arecibo while
there, and Daun pretty much built the whole thing hardware-wise. But
is that the dipoles talk to each other, and the driving impedance
dipole's feed point is not infinity, so radiation from each dipole
and phases of the currents in all the other dipoles, ad nauseum.
One option is careful system simulation, and I have put some effort
frankly it's not looking like a viable solution to me. Too many
guesses are involved. BTW, does anybody have a good Spice model for a
4CW150,000E power tetrode?
Another is direct measurement of the feed point complex currents with
coils (or similar sensors), but this is not trivial and would require
of significant funds in the sensors and in phase-matched cables running
the TX building. Nevertheless I suspect this is the best way.
Another, that is more economical, is to make all the transmission lines
integer number of half waves, and make the measurements at the TX end
cables. I worked out a way of doing the measurements with
of which sufficient extras came installed in the transmitters. I used
for trimming our feedlines to the same "length" (although they could
integer multiples of a half-wave), and it looked very promising. But
in actual operation requires building a bunch of additional
yet had the time or money to do so.
So, at present the technique used is to measure amplitude and phase of
wave (only) at the TX end of each line, basically by hand, and
transmitters' drive signals until we're happy with the results. This
working OK, but we don't know for sure, and it's a royal pain to do in
real problem is that this method does not really account for
dipoles, especially given that the transmitters' output are "power
impedance matched). BTW, does anybody have a good Spice model for a
The means for setting phases is via computer control of the stuff that
with a Python program written by another engineer (who has also left
But now, I can get to my other idea for optimizing phasing, which is to
emitted light in real time and crank on the "knobs" until the spot
most compact. It could even be done with a camera at a very remote
internet, thus allowing a camera location where the skies are really
Culebra site comes to mind for this.
On Sun, Jun 28, 2020 at 6:58 AM Ethan Miller K8GU via mvus-list <
Sorry I missed the MVUS showing of Arecibo photos. I had an HF
receiver and a relatively sensitive all-sky (fisheye) imager (the
imager is still there but operated by someone else now) in Culebra
a couple of years (for a different experiment) that was occasionally
repurposed for Arecibo HF experiments. It's pretty wild to see some
of the ionospheric structures they created with the HF system,
including airglow structures that were sub-visual magnitude blinking
on and off with the HF transmitter. Of course, at HAARP they've done
visual magnitude airglow, which does nothing to quell the conspiracy
I'm not a hard-core plasma physicist, but the stimulated RF emissions
from the Arecibo HF were also always interesting to see...the
high-power HF mode converts into plasma waves which interact with
other and some of them mode convert back into electromagnetic waves
different frequencies, shifted by "natural frequencies" (for example
the electron gyrofrequency) of the plasma. These are the types of
things that are theorized to be explanations for long-delayed echoes
(LDEs) and other radio oddities. I'll have to see if I have any data
floating around still that is clear and illustrative to a
technically-literate non-expert audience...
On Sun, Jun 28, 2020 at 1:56 AM Lenny via mvus-list
Just wondering if I can use the pictures and description in the Mt
VHF Radio Club ("The Packrats") newsletter. I'm sure the members
Please let me know either way.
--Lenny W2BVH (newsletter editor)
On 6/27/2020 4:28 PM, Daun Yeagley via mvus-list wrote:
It's "fun" trying to sort through all my pictures from Arecibo,
they are stored by date, and who knows what I was doing on a
Anyway, here are some pictures of the HF transmitters, and the
antennas in the bottom of the dish. For scale, look for the
that are standing in the opening in the middle. (that's where
hoist stuff up to the platform). Also, on the last one, if you
carefully you can see the cables that make up the secondary
Repair. Re-use. Re-purpose. Recycle.
Altair could move their 150 ft dish at 10 degrees per second!
K4TO
On Mon, Jun 29, 2020 at 10:22 PM Dana Whitlow via mvus-list <
mvus-list@lists.febo.com> wrote:
> Tom,
>
> Did "they" qualify that statement about "fastest moving dish on the planet"
> with the size?
> I feel pretty sure that there must be (smaller) radar dishes which can move
> fast enough
> to track low-flying aircraft as they pass overhead.
>
> Dana
>
>
> On Mon, Jun 29, 2020 at 9:10 PM Tom Holmes via mvus-list <
> mvus-list@lists.febo.com> wrote:
>
> > Hi Ethan…
> >
> >
> >
> > Very cool! It would be interesting to see more on it all. I’m not a
> > photographer type at all but it is interesting to see what is done
> > optically compared to at RF.
> >
> >
> >
> > I once did a spectrum analyzer training class for the Navy in MD that was
> > dealing with dishes looking upwards. They were somewhat secretive about
> > what they were doing, so we settled on calling it radio astronomy. At one
> > point they showed me a 70’ dish that could go from horizon to horizon in
> > like 2 minutes. They claimed it was the fastest moving dish on the
> planet.
> > I’ve yet to find any stars or planets that move that quickly (wink-wink).
> > At least they didn’t have to shoot me when the class was over.
> >
> >
> >
> > Tom Holmes, N8ZM
> >
> >
> >
> > From: Ethan Miller K8GU <ethan@k8gu.com>
> > Sent: Monday, June 29, 2020 9:59 PM
> > To: Midwest VHF/UHF Society Mailing List <mvus-list@lists.febo.com>
> > Cc: Tom Holmes <tholmes@woh.rr.com>
> > Subject: Imagery (was Re: [mvus-list] Arecibo HF)
> >
> >
> >
> > Tom,
> >
> >
> >
> > Like "Fight Club," the first rule of UFOs is "don't talk about the UFOs."
> >
> >
> >
> > I don't currently have any equipment to do all-sky imaging. There are
> > several commercial sources and the pricing is from ~$10K to ~$100K. The
> > basic design is a fast off-the-shelf (f/2.8 or better) fisheye lens
> > combined with some carefully-designed fixed lenses to produce telecentric
> > rays through a bank of high-quality narrow-band interference filters
> (e.g.,
> > 2-nm bandwidth at half-max, OD5 in the stop-band, usually with other
> > requirements on film quality, etc; very custom). The filters are
> between 2
> > and 4 inches in diameter, so the telecentric requirement is pretty
> > stringent for many designs to keep the filter wavelength from shifting
> > across the image. The filters are often selectable by a motorized
> > filterwheel. Then, there are some more custom fixed optics that focus
> the
> > telecentric rays back onto the imaging detector. The precise choice of
> > detector depends a lot on the science you're trying to do. My experience
> > has been predominantly with consumer astronomical CCDs and CMOS detectors
> > from Atik, SBIG, and Andor (a little better than "consumer-grade"). I'll
> > see if I can find pictures of some of the instrumentation for you if
> you'd
> > like to geek out on it.
> >
> >
> >
> > The emissions we're looking at usually pretty faint and require long
> > integration (exposure) times to overcome measurement noise. The 630-nm
> > "red line" emission comes from an excited state of oxygen that's observed
> > in both the aurora and the airglow. Airglow is a by-product of the
> plasma
> > process of recombination, which is the reverse of production
> (ionization),
> > which is what the Sun does to create the ionosphere in the first place.
> > Red airglow comes from just below the peak plasma density of the F2
> region,
> > about 250 km up. Green airglow (557.7 nm) is a brighter oxygen emission
> > and comes from the E region, about 97 km altitude. If you've seen
> > astronomical photos of waves in the night sky, these are probably green
> > airglow. This is also the photochemistry as the green aurora, although
> the
> > driving process is the magnetosphere, not diurnal recombination.
> >
> >
> >
> > I've been "inside the fence" at Haleakala. I was a grad student at the
> > time and my advisor dropped into my office one day and said, "How do you
> > feel about going to Hawaii?" I responded affirmatively. The following
> > day, he came in and said, "How's Monday?" My host/minder was an USAF
> > contractor who had been an MP in Bosnia. The instrumentation (two
> separate
> > cameras) resided in several "huts" that could only be accessed by passing
> > through secure areas. The big dial locks on the doors made an impression
> > for sure. I don't think there would have been much "talking your way
> in,"
> > at least on the Air Force side. Their telescope can do things that the
> one
> > on the astronomy side can't. It moved really fast when they demo'ed it
> for
> > me. Of course, the night sky was amazing, too, with the clouds below
> you.
> >
> >
> >
> > Did that scratch the itch? Now I'm getting wanderlust...
> >
> >
> >
> > 73,
> >
> >
> >
> > --Ethan, K8GU.
> >
> >
> >
> >
> >
> >
> >
> > On Mon, Jun 29, 2020 at 7:00 PM Tom Holmes via mvus-list <
> > mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> > wrote:
> >
> > Ethan...
> >
> >
> >
> > Cool video, but don’t understand why the UFO's are moving but not the
> > stars 😉.
> >
> >
> >
> > Can you talk more about the hardware you have to do this?
> >
> >
> >
> > Have been to Haleakala a couple of times, but always had family so didn’t
> > make the effort to bluff my way into the observatory. Would have loved to
> > see it. I have been to Kitt's Peak in AZ, and to the VLA, both of which
> are
> > quite fascinating, each in their own way.
> >
> >
> >
> > Tom Holmes, N8ZM
> >
> >
> >
> > -----Original Message-----
> > From: mvus-list <mvus-list-bounces@lists.febo.com <mailto:
> > mvus-list-bounces@lists.febo.com> > On Behalf Of Ethan Miller K8GU via
> > mvus-list
> > Sent: Monday, June 29, 2020 6:44 PM
> > To: Midwest VHF/UHF Society Mailing List <mvus-list@lists.febo.com
> > <mailto:mvus-list@lists.febo.com> >
> > Cc: Ethan Miller K8GU <ethan@k8gu.com <mailto:ethan@k8gu.com> >
> > Subject: Re: [mvus-list] Arecibo HF
> >
> >
> >
> > Dana,
> >
> >
> >
> > Cool. Yes, there's quite a bit of mutual coupling in this system!
> >
> > I'm vaguely familiar with the source of the transmitters (I was
> >
> > involved with putting a newer instrument at the location of the West
> >
> > Coast counterpart), but have not gotten into the details of the feeds,
> >
> > antennas, etc. It's neat to hear the backstory on the role that you
> >
> > and Daun played!
> >
> >
> >
> > Here is a link to a time-lapse movie taken at the Observatory (for
> >
> > whatever reason, I can't lay my hands on data from the Culebra
> >
> > instrument during heating right now). About 24 seconds into the
> >
> > movie, you'll see a white spot in the center of the field of view
> >
> > blinking ON and OFF. That's the HF.
> >
> >
> >
> > <http://k8gu.com/webpost/ao151109_6300.avi>
> > http://k8gu.com/webpost/ao151109_6300.avi
> >
> >
> >
> > I believe the Arecibo imager was only looking at the 630-nm emission
> >
> > and my camera was configured for 557.7-nm, 589.3-nm, and OH broadband
> >
> > in the near-IR. Because this is a filterwheel system, each additional
> >
> > wavelength reduces temporal sampling. It becomes burdensome at the
> >
> > four-minute exposures we were doing! In case you wondered, for some
> >
> > reason, this imager is also out of focus. Mine was never that bad!
> >
> >
> >
> > The Culebra site is quite good for the Caribbean, better than Arecibo,
> >
> > but perhaps comparable to Bonaire, which is dry and not too overrun
> >
> > with tourists and hotels. It is nothing like a number of other
> >
> > optical sites where I've operated equipment, for example Cerro Tololo,
> >
> > Chile, and Haleakala, Hawaii. I have not been to the new site that
> >
> > they negotiated after the new management came in a couple of years
> >
> > ago. I'll try to drag out some more heating imagery and see what I
> >
> > have that I've never looked at. Believe it or not, my HF receiving
> >
> > data from Culebra has been more interesting than the imagery so far.
> >
> >
> >
> > We originally installed the imager to study a certain class of
> >
> > traveling ionospheric disturbances that are pretty commonly observed
> >
> > over Puerto Rico. There is a paper on this coming out in J. Geophys.
> >
> > Res. soon, led by Pedrina Santos, of Arecibo.
> >
> >
> >
> > The airport approach into CPX is pretty cool...going through that
> >
> > little pass that's not-quite-aligned with the runway! My coworker and
> >
> > I flew over on a Cape Air BN-2B Islander from SJU and had 4-5 Pelican
> >
> > cases full of gear. The pilot very carefully balanced the plane
> >
> > before we took off and I think we may have bumped another passenger.
> >
> > That was a great trip.
> >
> >
> >
> > 73,
> >
> >
> >
> > --Ethan, K8GU.
> >
> >
> >
> >
> >
> >
> >
> > On Mon, Jun 29, 2020 at 5:42 PM Dana Whitlow via mvus-list
> >
> > < <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> >
> > mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> > wrote:
> >
> > >
> >
> > > Ethan,
> >
> > >
> >
> > > What got me interested in "seeing" the light emission resulting from
> >
> > > operation of
> >
> > > Arecibo's HF system was in search of a better, more practical solution
> to
> >
> > > the
> >
> > > problem of properly phasing the transmitters' outputs into their
> > respective
> >
> > > dipoles
> >
> > > in the array. I designed the multi-phase splitter for Arecibo while
> > still
> >
> > > employed
> >
> > > there, and Daun pretty much built the whole thing hardware-wise. But
> > the
> >
> > > problem
> >
> > > is that the dipoles talk to each other, and the driving impedance
> > presented
> >
> > > to each
> >
> > > dipole's feed point is not infinity, so radiation from each dipole
> >
> > > affects the amplitudes
> >
> > > and phases of the currents in all the other dipoles, ad nauseum.
> >
> > >
> >
> > > One option is careful system simulation, and I have put some effort
> into
> >
> > > this, but
> >
> > > frankly it's not looking like a viable solution to me. Too many
> >
> > > imponderables and
> >
> > > guesses are involved. BTW, does anybody have a good Spice model for a
> >
> > > 4CW150,000E power tetrode?
> >
> > >
> >
> > > Another is direct measurement of the feed point complex currents with
> >
> > > Rogowski
> >
> > > coils (or similar sensors), but this is not trivial and would require
> the
> >
> > > expenditure
> >
> > > of significant funds in the sensors and in phase-matched cables running
> >
> > > back to
> >
> > > the TX building. Nevertheless I suspect this is the best way.
> >
> > >
> >
> > > Another, that is more economical, is to make all the transmission lines
> > an
> >
> > > exact
> >
> > > integer number of half waves, and make the measurements at the TX end
> of
> > the
> >
> > > cables. I worked out a way of doing the measurements with
> > dual-directional
> >
> > > couplers,
> >
> > > of which sufficient extras came installed in the transmitters. I used
> > this
> >
> > > basic technique
> >
> > > for trimming our feedlines to the same "length" (although they could
> > differ
> >
> > > in length by
> >
> > > integer multiples of a half-wave), and it looked very promising. But
> > using
> >
> > > the technique
> >
> > > in actual operation requires building a bunch of additional
> electronics,
> >
> > > and nobody has
> >
> > > yet had the time or money to do so.
> >
> > >
> >
> > > So, at present the technique used is to measure amplitude and phase of
> > the
> >
> > > *forward*
> >
> > > *wave* (only) at the TX end of each line, basically by hand, and
> >
> > > iteratively tweak on the
> >
> > > transmitters' drive signals until we're happy with the results. This
> >
> > > actually *seems* to be
> >
> > > working OK, but we don't know for sure, and it's a royal pain to do in
> > any
> >
> > > case. The
> >
> > > real problem is that this method does not really account for
> interactions
> >
> > > between the
> >
> > > dipoles, especially given that the transmitters' output are "power
> >
> > > matched", (not
> >
> > > impedance matched). BTW, does anybody have a good Spice model for a
> >
> > > 4CW150,000E
> >
> > > power tetrode?
> >
> > >
> >
> > > The means for setting phases is via computer control of the stuff that
> > Daun
> >
> > > put together,
> >
> > > with a Python program written by another engineer (who has also left
> the
> >
> > > observatory).
> >
> > >
> >
> > > But now, I can get to my other idea for optimizing phasing, which is to
> >
> > > view the spot of
> >
> > > emitted light in real time and crank on the "knobs" until the spot
> > becomes
> >
> > > brightest and
> >
> > > most compact. It could even be done with a camera at a very remote
> >
> > > location via the
> >
> > > internet, thus allowing a camera location where the skies are really
> > dark.
> >
> > > Naturally the
> >
> > > Culebra site comes to mind for this.
> >
> > >
> >
> > > Dana
> >
> > >
> >
> > >
> >
> > > On Sun, Jun 28, 2020 at 6:58 AM Ethan Miller K8GU via mvus-list <
> >
> > > <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> >
> > mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> > wrote:
> >
> > >
> >
> > > > Daun/Dana,
> >
> > > >
> >
> > > > Sorry I missed the MVUS showing of Arecibo photos. I had an HF
> >
> > > > receiver and a relatively sensitive all-sky (fisheye) imager (the
> >
> > > > imager is still there but operated by someone else now) in Culebra
> for
> >
> > > > a couple of years (for a different experiment) that was occasionally
> >
> > > > repurposed for Arecibo HF experiments. It's pretty wild to see some
> >
> > > > of the ionospheric structures they created with the HF system,
> >
> > > > including airglow structures that were sub-visual magnitude blinking
> >
> > > > on and off with the HF transmitter. Of course, at HAARP they've done
> >
> > > > visual magnitude airglow, which does nothing to quell the conspiracy
> >
> > > > theories!
> >
> > > >
> >
> > > > I'm not a hard-core plasma physicist, but the stimulated RF emissions
> >
> > > > from the Arecibo HF were also always interesting to see...the
> >
> > > > high-power HF mode converts into plasma waves which interact with
> each
> >
> > > > other and some of them mode convert back into electromagnetic waves
> at
> >
> > > > different frequencies, shifted by "natural frequencies" (for example
> >
> > > > the electron gyrofrequency) of the plasma. These are the types of
> >
> > > > things that are theorized to be explanations for long-delayed echoes
> >
> > > > (LDEs) and other radio oddities. I'll have to see if I have any data
> >
> > > > floating around still that is clear and illustrative to a
> >
> > > > technically-literate non-expert audience...
> >
> > > >
> >
> > > > 73,
> >
> > > >
> >
> > > > --Ethan, K8GU.
> >
> > > >
> >
> > > > On Sun, Jun 28, 2020 at 1:56 AM Lenny via mvus-list
> >
> > > > < <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
> > > mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> > wrote:
> >
> > > > >
> >
> > > > > Hi Daun
> >
> > > > >
> >
> > > > > Just wondering if I can use the pictures and description in the Mt
> > Airy
> >
> > > > > VHF Radio Club ("The Packrats") newsletter. I'm sure the members
> > would
> >
> > > > > be interested.
> >
> > > > >
> >
> > > > > Please let me know either way.
> >
> > > > >
> >
> > > > > Tnx, 73 & stay safe,
> >
> > > > >
> >
> > > > > --Lenny W2BVH (newsletter editor)
> >
> > > > >
> >
> > > > >
> >
> > > > >
> >
> > > > > On 6/27/2020 4:28 PM, Daun Yeagley via mvus-list wrote:
> >
> > > > > > It's "fun" trying to sort through all my pictures from Arecibo,
> as
> >
> > > > > > they are stored by date, and who knows what I was doing on a
> >
> > > > > > particular day!
> >
> > > > > >
> >
> > > > > > Anyway, here are some pictures of the HF transmitters, and the
> >
> > > > > > antennas in the bottom of the dish. For scale, look for the
> guys
> >
> > > > > > that are standing in the opening in the middle. (that's where
> they
> >
> > > > > > hoist stuff up to the platform). Also, on the last one, if you
> > look
> >
> > > > > > carefully you can see the cables that make up the secondary
> > reflector.
> >
> > > > > >
> >
> > > > > > Daun
> >
> > > > > >
> >
> > > > > >
> >
> > > > > > _______________________________________________
> >
> > > > > > mvus-list mailing list
> >
> > > > > > <mailto:mvus-list@lists.febo.com <mailto:
> mvus-list@lists.febo.com>
> > > mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
> >
> > > > > > <
> http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com>
> > http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
> >
> > > > > _______________________________________________
> >
> > > > > mvus-list mailing list
> >
> > > > > <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com
> >
> > > mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
> >
> > > > > <http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com>
> > http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
> >
> > > >
> >
> > > >
> >
> > > >
> >
> > > > --
> >
> > > > <http://www.k8gu.com/> http://www.k8gu.com/
> >
> > > > Repair. Re-use. Re-purpose. Recycle.
> >
> > > >
> >
> > > > _______________________________________________
> >
> > > > mvus-list mailing list
> >
> > > > <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
> >
> > mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
> >
> > > > <http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com>
> > http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
> >
> > > >
> >
> > > _______________________________________________
> >
> > > mvus-list mailing list
> >
> > > <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> >
> > mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
> >
> > > <http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com>
> > http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
> >
> >
> >
> >
> >
> >
> >
> > --
> >
> > <http://www.k8gu.com/> http://www.k8gu.com/
> >
> > Repair. Re-use. Re-purpose. Recycle.
> >
> >
> >
> > _______________________________________________
> >
> > mvus-list mailing list
> >
> > <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> >
> > mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
> >
> > <http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com>
> > http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
> >
> > _______________________________________________
> > mvus-list mailing list
> > mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
> > http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
> >
> >
> >
> > --
> >
> > http://www.k8gu.com/
> > Repair. Re-use. Re-purpose. Recycle.
> >
> > _______________________________________________
> > mvus-list mailing list
> > mvus-list@lists.febo.com
> > http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
> >
> _______________________________________________
> mvus-list mailing list
> mvus-list@lists.febo.com
> http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
>
TH
Tom Holmes
Tue, Jun 30, 2020 2:50 AM
I don’t recall that they did, but they might have said ‘of its size’ while I was considering the possibilities for rapid-fire microwave QSO’s.
From Tom Holmes, N8ZM
On Jun 29, 2020, at 10:22 PM, Dana Whitlow via mvus-list mvus-list@lists.febo.com wrote:
Tom,
Did "they" qualify that statement about "fastest moving dish on the planet"
with the size?
I feel pretty sure that there must be (smaller) radar dishes which can move
fast enough
to track low-flying aircraft as they pass overhead.
Dana
On Mon, Jun 29, 2020 at 9:10 PM Tom Holmes via mvus-list <
mvus-list@lists.febo.com> wrote:
Hi Ethan…
Very cool! It would be interesting to see more on it all. I’m not a
photographer type at all but it is interesting to see what is done
optically compared to at RF.
I once did a spectrum analyzer training class for the Navy in MD that was
dealing with dishes looking upwards. They were somewhat secretive about
what they were doing, so we settled on calling it radio astronomy. At one
point they showed me a 70’ dish that could go from horizon to horizon in
like 2 minutes. They claimed it was the fastest moving dish on the planet.
I’ve yet to find any stars or planets that move that quickly (wink-wink).
At least they didn’t have to shoot me when the class was over.
Tom Holmes, N8ZM
From: Ethan Miller K8GU ethan@k8gu.com
Sent: Monday, June 29, 2020 9:59 PM
To: Midwest VHF/UHF Society Mailing List mvus-list@lists.febo.com
Cc: Tom Holmes tholmes@woh.rr.com
Subject: Imagery (was Re: [mvus-list] Arecibo HF)
Tom,
Like "Fight Club," the first rule of UFOs is "don't talk about the UFOs."
I don't currently have any equipment to do all-sky imaging. There are
several commercial sources and the pricing is from ~$10K to ~$100K. The
basic design is a fast off-the-shelf (f/2.8 or better) fisheye lens
combined with some carefully-designed fixed lenses to produce telecentric
rays through a bank of high-quality narrow-band interference filters (e.g.,
2-nm bandwidth at half-max, OD5 in the stop-band, usually with other
requirements on film quality, etc; very custom). The filters are between 2
and 4 inches in diameter, so the telecentric requirement is pretty
stringent for many designs to keep the filter wavelength from shifting
across the image. The filters are often selectable by a motorized
filterwheel. Then, there are some more custom fixed optics that focus the
telecentric rays back onto the imaging detector. The precise choice of
detector depends a lot on the science you're trying to do. My experience
has been predominantly with consumer astronomical CCDs and CMOS detectors
from Atik, SBIG, and Andor (a little better than "consumer-grade"). I'll
see if I can find pictures of some of the instrumentation for you if you'd
like to geek out on it.
The emissions we're looking at usually pretty faint and require long
integration (exposure) times to overcome measurement noise. The 630-nm
"red line" emission comes from an excited state of oxygen that's observed
in both the aurora and the airglow. Airglow is a by-product of the plasma
process of recombination, which is the reverse of production (ionization),
which is what the Sun does to create the ionosphere in the first place.
Red airglow comes from just below the peak plasma density of the F2 region,
about 250 km up. Green airglow (557.7 nm) is a brighter oxygen emission
and comes from the E region, about 97 km altitude. If you've seen
astronomical photos of waves in the night sky, these are probably green
airglow. This is also the photochemistry as the green aurora, although the
driving process is the magnetosphere, not diurnal recombination.
I've been "inside the fence" at Haleakala. I was a grad student at the
time and my advisor dropped into my office one day and said, "How do you
feel about going to Hawaii?" I responded affirmatively. The following
day, he came in and said, "How's Monday?" My host/minder was an USAF
contractor who had been an MP in Bosnia. The instrumentation (two separate
cameras) resided in several "huts" that could only be accessed by passing
through secure areas. The big dial locks on the doors made an impression
for sure. I don't think there would have been much "talking your way in,"
at least on the Air Force side. Their telescope can do things that the one
on the astronomy side can't. It moved really fast when they demo'ed it for
me. Of course, the night sky was amazing, too, with the clouds below you.
Did that scratch the itch? Now I'm getting wanderlust...
73,
--Ethan, K8GU.
On Mon, Jun 29, 2020 at 7:00 PM Tom Holmes via mvus-list <
mvus-list@lists.febo.com mailto:mvus-list@lists.febo.com > wrote:
Ethan...
Cool video, but don’t understand why the UFO's are moving but not the
stars 😉.
Can you talk more about the hardware you have to do this?
Have been to Haleakala a couple of times, but always had family so didn’t
make the effort to bluff my way into the observatory. Would have loved to
see it. I have been to Kitt's Peak in AZ, and to the VLA, both of which are
quite fascinating, each in their own way.
Tom Holmes, N8ZM
-----Original Message-----
From: mvus-list <mvus-list-bounces@lists.febo.com <mailto:
mvus-list-bounces@lists.febo.com> > On Behalf Of Ethan Miller K8GU via
mvus-list
Sent: Monday, June 29, 2020 6:44 PM
To: Midwest VHF/UHF Society Mailing List <mvus-list@lists.febo.com
mailto:mvus-list@lists.febo.com >
Cc: Ethan Miller K8GU <ethan@k8gu.com mailto:ethan@k8gu.com >
Subject: Re: [mvus-list] Arecibo HF
Dana,
Cool. Yes, there's quite a bit of mutual coupling in this system!
I'm vaguely familiar with the source of the transmitters (I was
involved with putting a newer instrument at the location of the West
Coast counterpart), but have not gotten into the details of the feeds,
antennas, etc. It's neat to hear the backstory on the role that you
and Daun played!
Here is a link to a time-lapse movie taken at the Observatory (for
whatever reason, I can't lay my hands on data from the Culebra
instrument during heating right now). About 24 seconds into the
movie, you'll see a white spot in the center of the field of view
blinking ON and OFF. That's the HF.
http://k8gu.com/webpost/ao151109_6300.avi
http://k8gu.com/webpost/ao151109_6300.avi
I believe the Arecibo imager was only looking at the 630-nm emission
and my camera was configured for 557.7-nm, 589.3-nm, and OH broadband
in the near-IR. Because this is a filterwheel system, each additional
wavelength reduces temporal sampling. It becomes burdensome at the
four-minute exposures we were doing! In case you wondered, for some
reason, this imager is also out of focus. Mine was never that bad!
The Culebra site is quite good for the Caribbean, better than Arecibo,
but perhaps comparable to Bonaire, which is dry and not too overrun
with tourists and hotels. It is nothing like a number of other
optical sites where I've operated equipment, for example Cerro Tololo,
Chile, and Haleakala, Hawaii. I have not been to the new site that
they negotiated after the new management came in a couple of years
ago. I'll try to drag out some more heating imagery and see what I
have that I've never looked at. Believe it or not, my HF receiving
data from Culebra has been more interesting than the imagery so far.
We originally installed the imager to study a certain class of
traveling ionospheric disturbances that are pretty commonly observed
over Puerto Rico. There is a paper on this coming out in J. Geophys.
Res. soon, led by Pedrina Santos, of Arecibo.
The airport approach into CPX is pretty cool...going through that
little pass that's not-quite-aligned with the runway! My coworker and
I flew over on a Cape Air BN-2B Islander from SJU and had 4-5 Pelican
cases full of gear. The pilot very carefully balanced the plane
before we took off and I think we may have bumped another passenger.
That was a great trip.
73,
--Ethan, K8GU.
On Mon, Jun 29, 2020 at 5:42 PM Dana Whitlow via mvus-list
< <mailto:mvus-list@lists.febo.com mailto:mvus-list@lists.febo.com >
mvus-list@lists.febo.com mailto:mvus-list@lists.febo.com > wrote:
What got me interested in "seeing" the light emission resulting from
Arecibo's HF system was in search of a better, more practical solution to
problem of properly phasing the transmitters' outputs into their
in the array. I designed the multi-phase splitter for Arecibo while
there, and Daun pretty much built the whole thing hardware-wise. But
is that the dipoles talk to each other, and the driving impedance
dipole's feed point is not infinity, so radiation from each dipole
and phases of the currents in all the other dipoles, ad nauseum.
One option is careful system simulation, and I have put some effort into
frankly it's not looking like a viable solution to me. Too many
guesses are involved. BTW, does anybody have a good Spice model for a
4CW150,000E power tetrode?
Another is direct measurement of the feed point complex currents with
coils (or similar sensors), but this is not trivial and would require the
of significant funds in the sensors and in phase-matched cables running
the TX building. Nevertheless I suspect this is the best way.
Another, that is more economical, is to make all the transmission lines
integer number of half waves, and make the measurements at the TX end of
cables. I worked out a way of doing the measurements with
of which sufficient extras came installed in the transmitters. I used
for trimming our feedlines to the same "length" (although they could
integer multiples of a half-wave), and it looked very promising. But
in actual operation requires building a bunch of additional electronics,
yet had the time or money to do so.
So, at present the technique used is to measure amplitude and phase of
wave (only) at the TX end of each line, basically by hand, and
transmitters' drive signals until we're happy with the results. This
working OK, but we don't know for sure, and it's a royal pain to do in
real problem is that this method does not really account for interactions
dipoles, especially given that the transmitters' output are "power
impedance matched). BTW, does anybody have a good Spice model for a
The means for setting phases is via computer control of the stuff that
with a Python program written by another engineer (who has also left the
But now, I can get to my other idea for optimizing phasing, which is to
emitted light in real time and crank on the "knobs" until the spot
most compact. It could even be done with a camera at a very remote
internet, thus allowing a camera location where the skies are really
Culebra site comes to mind for this.
On Sun, Jun 28, 2020 at 6:58 AM Ethan Miller K8GU via mvus-list <
Sorry I missed the MVUS showing of Arecibo photos. I had an HF
receiver and a relatively sensitive all-sky (fisheye) imager (the
imager is still there but operated by someone else now) in Culebra for
a couple of years (for a different experiment) that was occasionally
repurposed for Arecibo HF experiments. It's pretty wild to see some
of the ionospheric structures they created with the HF system,
including airglow structures that were sub-visual magnitude blinking
on and off with the HF transmitter. Of course, at HAARP they've done
visual magnitude airglow, which does nothing to quell the conspiracy
I'm not a hard-core plasma physicist, but the stimulated RF emissions
from the Arecibo HF were also always interesting to see...the
high-power HF mode converts into plasma waves which interact with each
other and some of them mode convert back into electromagnetic waves at
different frequencies, shifted by "natural frequencies" (for example
the electron gyrofrequency) of the plasma. These are the types of
things that are theorized to be explanations for long-delayed echoes
(LDEs) and other radio oddities. I'll have to see if I have any data
floating around still that is clear and illustrative to a
technically-literate non-expert audience...
On Sun, Jun 28, 2020 at 1:56 AM Lenny via mvus-list
Just wondering if I can use the pictures and description in the Mt
VHF Radio Club ("The Packrats") newsletter. I'm sure the members
Please let me know either way.
--Lenny W2BVH (newsletter editor)
On 6/27/2020 4:28 PM, Daun Yeagley via mvus-list wrote:
It's "fun" trying to sort through all my pictures from Arecibo, as
they are stored by date, and who knows what I was doing on a
Anyway, here are some pictures of the HF transmitters, and the
antennas in the bottom of the dish. For scale, look for the guys
that are standing in the opening in the middle. (that's where they
hoist stuff up to the platform). Also, on the last one, if you
carefully you can see the cables that make up the secondary
Repair. Re-use. Re-purpose. Recycle.
I don’t recall that they did, but they might have said ‘of its size’ while I was considering the possibilities for rapid-fire microwave QSO’s.
From Tom Holmes, N8ZM
> On Jun 29, 2020, at 10:22 PM, Dana Whitlow via mvus-list <mvus-list@lists.febo.com> wrote:
>
> Tom,
>
> Did "they" qualify that statement about "fastest moving dish on the planet"
> with the size?
> I feel pretty sure that there must be (smaller) radar dishes which can move
> fast enough
> to track low-flying aircraft as they pass overhead.
>
> Dana
>
>
>> On Mon, Jun 29, 2020 at 9:10 PM Tom Holmes via mvus-list <
>> mvus-list@lists.febo.com> wrote:
>>
>> Hi Ethan…
>>
>>
>>
>> Very cool! It would be interesting to see more on it all. I’m not a
>> photographer type at all but it is interesting to see what is done
>> optically compared to at RF.
>>
>>
>>
>> I once did a spectrum analyzer training class for the Navy in MD that was
>> dealing with dishes looking upwards. They were somewhat secretive about
>> what they were doing, so we settled on calling it radio astronomy. At one
>> point they showed me a 70’ dish that could go from horizon to horizon in
>> like 2 minutes. They claimed it was the fastest moving dish on the planet.
>> I’ve yet to find any stars or planets that move that quickly (wink-wink).
>> At least they didn’t have to shoot me when the class was over.
>>
>>
>>
>> Tom Holmes, N8ZM
>>
>>
>>
>> From: Ethan Miller K8GU <ethan@k8gu.com>
>> Sent: Monday, June 29, 2020 9:59 PM
>> To: Midwest VHF/UHF Society Mailing List <mvus-list@lists.febo.com>
>> Cc: Tom Holmes <tholmes@woh.rr.com>
>> Subject: Imagery (was Re: [mvus-list] Arecibo HF)
>>
>>
>>
>> Tom,
>>
>>
>>
>> Like "Fight Club," the first rule of UFOs is "don't talk about the UFOs."
>>
>>
>>
>> I don't currently have any equipment to do all-sky imaging. There are
>> several commercial sources and the pricing is from ~$10K to ~$100K. The
>> basic design is a fast off-the-shelf (f/2.8 or better) fisheye lens
>> combined with some carefully-designed fixed lenses to produce telecentric
>> rays through a bank of high-quality narrow-band interference filters (e.g.,
>> 2-nm bandwidth at half-max, OD5 in the stop-band, usually with other
>> requirements on film quality, etc; very custom). The filters are between 2
>> and 4 inches in diameter, so the telecentric requirement is pretty
>> stringent for many designs to keep the filter wavelength from shifting
>> across the image. The filters are often selectable by a motorized
>> filterwheel. Then, there are some more custom fixed optics that focus the
>> telecentric rays back onto the imaging detector. The precise choice of
>> detector depends a lot on the science you're trying to do. My experience
>> has been predominantly with consumer astronomical CCDs and CMOS detectors
>> from Atik, SBIG, and Andor (a little better than "consumer-grade"). I'll
>> see if I can find pictures of some of the instrumentation for you if you'd
>> like to geek out on it.
>>
>>
>>
>> The emissions we're looking at usually pretty faint and require long
>> integration (exposure) times to overcome measurement noise. The 630-nm
>> "red line" emission comes from an excited state of oxygen that's observed
>> in both the aurora and the airglow. Airglow is a by-product of the plasma
>> process of recombination, which is the reverse of production (ionization),
>> which is what the Sun does to create the ionosphere in the first place.
>> Red airglow comes from just below the peak plasma density of the F2 region,
>> about 250 km up. Green airglow (557.7 nm) is a brighter oxygen emission
>> and comes from the E region, about 97 km altitude. If you've seen
>> astronomical photos of waves in the night sky, these are probably green
>> airglow. This is also the photochemistry as the green aurora, although the
>> driving process is the magnetosphere, not diurnal recombination.
>>
>>
>>
>> I've been "inside the fence" at Haleakala. I was a grad student at the
>> time and my advisor dropped into my office one day and said, "How do you
>> feel about going to Hawaii?" I responded affirmatively. The following
>> day, he came in and said, "How's Monday?" My host/minder was an USAF
>> contractor who had been an MP in Bosnia. The instrumentation (two separate
>> cameras) resided in several "huts" that could only be accessed by passing
>> through secure areas. The big dial locks on the doors made an impression
>> for sure. I don't think there would have been much "talking your way in,"
>> at least on the Air Force side. Their telescope can do things that the one
>> on the astronomy side can't. It moved really fast when they demo'ed it for
>> me. Of course, the night sky was amazing, too, with the clouds below you.
>>
>>
>>
>> Did that scratch the itch? Now I'm getting wanderlust...
>>
>>
>>
>> 73,
>>
>>
>>
>> --Ethan, K8GU.
>>
>>
>>
>>
>>
>>
>>
>> On Mon, Jun 29, 2020 at 7:00 PM Tom Holmes via mvus-list <
>> mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> > wrote:
>>
>> Ethan...
>>
>>
>>
>> Cool video, but don’t understand why the UFO's are moving but not the
>> stars 😉.
>>
>>
>>
>> Can you talk more about the hardware you have to do this?
>>
>>
>>
>> Have been to Haleakala a couple of times, but always had family so didn’t
>> make the effort to bluff my way into the observatory. Would have loved to
>> see it. I have been to Kitt's Peak in AZ, and to the VLA, both of which are
>> quite fascinating, each in their own way.
>>
>>
>>
>> Tom Holmes, N8ZM
>>
>>
>>
>> -----Original Message-----
>> From: mvus-list <mvus-list-bounces@lists.febo.com <mailto:
>> mvus-list-bounces@lists.febo.com> > On Behalf Of Ethan Miller K8GU via
>> mvus-list
>> Sent: Monday, June 29, 2020 6:44 PM
>> To: Midwest VHF/UHF Society Mailing List <mvus-list@lists.febo.com
>> <mailto:mvus-list@lists.febo.com> >
>> Cc: Ethan Miller K8GU <ethan@k8gu.com <mailto:ethan@k8gu.com> >
>> Subject: Re: [mvus-list] Arecibo HF
>>
>>
>>
>> Dana,
>>
>>
>>
>> Cool. Yes, there's quite a bit of mutual coupling in this system!
>>
>> I'm vaguely familiar with the source of the transmitters (I was
>>
>> involved with putting a newer instrument at the location of the West
>>
>> Coast counterpart), but have not gotten into the details of the feeds,
>>
>> antennas, etc. It's neat to hear the backstory on the role that you
>>
>> and Daun played!
>>
>>
>>
>> Here is a link to a time-lapse movie taken at the Observatory (for
>>
>> whatever reason, I can't lay my hands on data from the Culebra
>>
>> instrument during heating right now). About 24 seconds into the
>>
>> movie, you'll see a white spot in the center of the field of view
>>
>> blinking ON and OFF. That's the HF.
>>
>>
>>
>> <http://k8gu.com/webpost/ao151109_6300.avi>
>> http://k8gu.com/webpost/ao151109_6300.avi
>>
>>
>>
>> I believe the Arecibo imager was only looking at the 630-nm emission
>>
>> and my camera was configured for 557.7-nm, 589.3-nm, and OH broadband
>>
>> in the near-IR. Because this is a filterwheel system, each additional
>>
>> wavelength reduces temporal sampling. It becomes burdensome at the
>>
>> four-minute exposures we were doing! In case you wondered, for some
>>
>> reason, this imager is also out of focus. Mine was never that bad!
>>
>>
>>
>> The Culebra site is quite good for the Caribbean, better than Arecibo,
>>
>> but perhaps comparable to Bonaire, which is dry and not too overrun
>>
>> with tourists and hotels. It is nothing like a number of other
>>
>> optical sites where I've operated equipment, for example Cerro Tololo,
>>
>> Chile, and Haleakala, Hawaii. I have not been to the new site that
>>
>> they negotiated after the new management came in a couple of years
>>
>> ago. I'll try to drag out some more heating imagery and see what I
>>
>> have that I've never looked at. Believe it or not, my HF receiving
>>
>> data from Culebra has been more interesting than the imagery so far.
>>
>>
>>
>> We originally installed the imager to study a certain class of
>>
>> traveling ionospheric disturbances that are pretty commonly observed
>>
>> over Puerto Rico. There is a paper on this coming out in J. Geophys.
>>
>> Res. soon, led by Pedrina Santos, of Arecibo.
>>
>>
>>
>> The airport approach into CPX is pretty cool...going through that
>>
>> little pass that's not-quite-aligned with the runway! My coworker and
>>
>> I flew over on a Cape Air BN-2B Islander from SJU and had 4-5 Pelican
>>
>> cases full of gear. The pilot very carefully balanced the plane
>>
>> before we took off and I think we may have bumped another passenger.
>>
>> That was a great trip.
>>
>>
>>
>> 73,
>>
>>
>>
>> --Ethan, K8GU.
>>
>>
>>
>>
>>
>>
>>
>> On Mon, Jun 29, 2020 at 5:42 PM Dana Whitlow via mvus-list
>>
>> < <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> >
>> mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> > wrote:
>>
>>>
>>
>>> Ethan,
>>
>>>
>>
>>> What got me interested in "seeing" the light emission resulting from
>>
>>> operation of
>>
>>> Arecibo's HF system was in search of a better, more practical solution to
>>
>>> the
>>
>>> problem of properly phasing the transmitters' outputs into their
>> respective
>>
>>> dipoles
>>
>>> in the array. I designed the multi-phase splitter for Arecibo while
>> still
>>
>>> employed
>>
>>> there, and Daun pretty much built the whole thing hardware-wise. But
>> the
>>
>>> problem
>>
>>> is that the dipoles talk to each other, and the driving impedance
>> presented
>>
>>> to each
>>
>>> dipole's feed point is not infinity, so radiation from each dipole
>>
>>> affects the amplitudes
>>
>>> and phases of the currents in all the other dipoles, ad nauseum.
>>
>>>
>>
>>> One option is careful system simulation, and I have put some effort into
>>
>>> this, but
>>
>>> frankly it's not looking like a viable solution to me. Too many
>>
>>> imponderables and
>>
>>> guesses are involved. BTW, does anybody have a good Spice model for a
>>
>>> 4CW150,000E power tetrode?
>>
>>>
>>
>>> Another is direct measurement of the feed point complex currents with
>>
>>> Rogowski
>>
>>> coils (or similar sensors), but this is not trivial and would require the
>>
>>> expenditure
>>
>>> of significant funds in the sensors and in phase-matched cables running
>>
>>> back to
>>
>>> the TX building. Nevertheless I suspect this is the best way.
>>
>>>
>>
>>> Another, that is more economical, is to make all the transmission lines
>> an
>>
>>> exact
>>
>>> integer number of half waves, and make the measurements at the TX end of
>> the
>>
>>> cables. I worked out a way of doing the measurements with
>> dual-directional
>>
>>> couplers,
>>
>>> of which sufficient extras came installed in the transmitters. I used
>> this
>>
>>> basic technique
>>
>>> for trimming our feedlines to the same "length" (although they could
>> differ
>>
>>> in length by
>>
>>> integer multiples of a half-wave), and it looked very promising. But
>> using
>>
>>> the technique
>>
>>> in actual operation requires building a bunch of additional electronics,
>>
>>> and nobody has
>>
>>> yet had the time or money to do so.
>>
>>>
>>
>>> So, at present the technique used is to measure amplitude and phase of
>> the
>>
>>> *forward*
>>
>>> *wave* (only) at the TX end of each line, basically by hand, and
>>
>>> iteratively tweak on the
>>
>>> transmitters' drive signals until we're happy with the results. This
>>
>>> actually *seems* to be
>>
>>> working OK, but we don't know for sure, and it's a royal pain to do in
>> any
>>
>>> case. The
>>
>>> real problem is that this method does not really account for interactions
>>
>>> between the
>>
>>> dipoles, especially given that the transmitters' output are "power
>>
>>> matched", (not
>>
>>> impedance matched). BTW, does anybody have a good Spice model for a
>>
>>> 4CW150,000E
>>
>>> power tetrode?
>>
>>>
>>
>>> The means for setting phases is via computer control of the stuff that
>> Daun
>>
>>> put together,
>>
>>> with a Python program written by another engineer (who has also left the
>>
>>> observatory).
>>
>>>
>>
>>> But now, I can get to my other idea for optimizing phasing, which is to
>>
>>> view the spot of
>>
>>> emitted light in real time and crank on the "knobs" until the spot
>> becomes
>>
>>> brightest and
>>
>>> most compact. It could even be done with a camera at a very remote
>>
>>> location via the
>>
>>> internet, thus allowing a camera location where the skies are really
>> dark.
>>
>>> Naturally the
>>
>>> Culebra site comes to mind for this.
>>
>>>
>>
>>> Dana
>>
>>>
>>
>>>
>>
>>> On Sun, Jun 28, 2020 at 6:58 AM Ethan Miller K8GU via mvus-list <
>>
>>> <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> >
>> mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> > wrote:
>>
>>>
>>
>>>> Daun/Dana,
>>
>>>>
>>
>>>> Sorry I missed the MVUS showing of Arecibo photos. I had an HF
>>
>>>> receiver and a relatively sensitive all-sky (fisheye) imager (the
>>
>>>> imager is still there but operated by someone else now) in Culebra for
>>
>>>> a couple of years (for a different experiment) that was occasionally
>>
>>>> repurposed for Arecibo HF experiments. It's pretty wild to see some
>>
>>>> of the ionospheric structures they created with the HF system,
>>
>>>> including airglow structures that were sub-visual magnitude blinking
>>
>>>> on and off with the HF transmitter. Of course, at HAARP they've done
>>
>>>> visual magnitude airglow, which does nothing to quell the conspiracy
>>
>>>> theories!
>>
>>>>
>>
>>>> I'm not a hard-core plasma physicist, but the stimulated RF emissions
>>
>>>> from the Arecibo HF were also always interesting to see...the
>>
>>>> high-power HF mode converts into plasma waves which interact with each
>>
>>>> other and some of them mode convert back into electromagnetic waves at
>>
>>>> different frequencies, shifted by "natural frequencies" (for example
>>
>>>> the electron gyrofrequency) of the plasma. These are the types of
>>
>>>> things that are theorized to be explanations for long-delayed echoes
>>
>>>> (LDEs) and other radio oddities. I'll have to see if I have any data
>>
>>>> floating around still that is clear and illustrative to a
>>
>>>> technically-literate non-expert audience...
>>
>>>>
>>
>>>> 73,
>>
>>>>
>>
>>>> --Ethan, K8GU.
>>
>>>>
>>
>>>> On Sun, Jun 28, 2020 at 1:56 AM Lenny via mvus-list
>>
>>>> < <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
>>> mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> > wrote:
>>
>>>>>
>>
>>>>> Hi Daun
>>
>>>>>
>>
>>>>> Just wondering if I can use the pictures and description in the Mt
>> Airy
>>
>>>>> VHF Radio Club ("The Packrats") newsletter. I'm sure the members
>> would
>>
>>>>> be interested.
>>
>>>>>
>>
>>>>> Please let me know either way.
>>
>>>>>
>>
>>>>> Tnx, 73 & stay safe,
>>
>>>>>
>>
>>>>> --Lenny W2BVH (newsletter editor)
>>
>>>>>
>>
>>>>>
>>
>>>>>
>>
>>>>> On 6/27/2020 4:28 PM, Daun Yeagley via mvus-list wrote:
>>
>>>>>> It's "fun" trying to sort through all my pictures from Arecibo, as
>>
>>>>>> they are stored by date, and who knows what I was doing on a
>>
>>>>>> particular day!
>>
>>>>>>
>>
>>>>>> Anyway, here are some pictures of the HF transmitters, and the
>>
>>>>>> antennas in the bottom of the dish. For scale, look for the guys
>>
>>>>>> that are standing in the opening in the middle. (that's where they
>>
>>>>>> hoist stuff up to the platform). Also, on the last one, if you
>> look
>>
>>>>>> carefully you can see the cables that make up the secondary
>> reflector.
>>
>>>>>>
>>
>>>>>> Daun
>>
>>>>>>
>>
>>>>>>
>>
>>>>>> _______________________________________________
>>
>>>>>> mvus-list mailing list
>>
>>>>>> <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
>>> mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
>>
>>>>>> <http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com>
>> http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
>>
>>>>> _______________________________________________
>>
>>>>> mvus-list mailing list
>>
>>>>> <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
>>> mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
>>
>>>>> <http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com>
>> http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
>>
>>>>
>>
>>>>
>>
>>>>
>>
>>>> --
>>
>>>> <http://www.k8gu.com/> http://www.k8gu.com/
>>
>>>> Repair. Re-use. Re-purpose. Recycle.
>>
>>>>
>>
>>>> _______________________________________________
>>
>>>> mvus-list mailing list
>>
>>>> <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> >
>> mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
>>
>>>> <http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com>
>> http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
>>
>>>>
>>
>>> _______________________________________________
>>
>>> mvus-list mailing list
>>
>>> <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> >
>> mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
>>
>>> <http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com>
>> http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
>>
>>
>>
>>
>>
>>
>>
>> --
>>
>> <http://www.k8gu.com/> http://www.k8gu.com/
>>
>> Repair. Re-use. Re-purpose. Recycle.
>>
>>
>>
>> _______________________________________________
>>
>> mvus-list mailing list
>>
>> <mailto:mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com> >
>> mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
>>
>> <http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com>
>> http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
>>
>> _______________________________________________
>> mvus-list mailing list
>> mvus-list@lists.febo.com <mailto:mvus-list@lists.febo.com>
>> http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
>>
>>
>>
>> --
>>
>> http://www.k8gu.com/
>> Repair. Re-use. Re-purpose. Recycle.
>>
>> _______________________________________________
>> mvus-list mailing list
>> mvus-list@lists.febo.com
>> http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
>>
> _______________________________________________
> mvus-list mailing list
> mvus-list@lists.febo.com
> http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
EM
Ethan Miller K8GU
Tue, Jun 30, 2020 11:00 AM
Dana, et al,
They're anywhere from 0.5 nm to 3 nm bandwidth at half-max (FWHM).
The efficiency numbers vary from 50%-90% if I recall correctly.
Typical exposure times are 60 to 300 seconds per image. There are
some very sensitive and image-intensified auroral imagers and I
believe AFRL Space Vehicles have an airglow imager that approaches
video frame rates. But, these are an order of magnitude more
expensive and fiddly, as well as filling disks quickly. I referred to
my video as "time-lapse" but you may have missed that. The video I
sent is also very raw; typically, videos meant for public consumption
are annotated with metadata about date/time, wavelength, cardinal
directions, etc; they usually have the hot pixels and sometimes stars
(you should have seen Orion near the heater airglow) removed. The
images can also be "unwarped" onto a map, assuming the airglow
emanates from a uniform altitude.
The only time I had experience with 0.5-nm filters was for a
spacecraft instrument. We tuned it by varying the temperature of the
plate it was mounted in. The CTE of the filter material determined
the wavelength shift as we heated the mounting plate. To bring this
discussion full-circle, we used an ionospheric diagnostic mode
(incoherent scatter) of the ALTAIR radar in Kwajalein that Dave, K4TO,
mentioned as a part of the calibration effort for the primary portion
(a UV spectrograph) of that instrument. It had no problem tracking
the spacecraft. I simply used heavy clouds under full moon
illumination to cross-calibrate the visible photometers (that had the
aforementioned filters), though.
73,
--Ethan, K8GU.
On Mon, Jun 29, 2020 at 10:14 PM Dana Whitlow via mvus-list
mvus-list@lists.febo.com wrote:
Ethan,
What is the bandwidth of typical filters used in upper atmosphere
studies?
You've made a couple of references to long time exposures. Yet
watching the videos of Arecibo-driven light emission while I was
there gave me the distinct impression that this was normal video
at normal frame rates. Was that just wishful thinking on my part?
Note that I've not yet watched the video you attached- the only
PC I have that may be able to play AVI format is rather busy at the
moment doing other things.
Dana
On Mon, Jun 29, 2020 at 8:59 PM Ethan Miller K8GU via mvus-list <
mvus-list@lists.febo.com> wrote:
Tom,
Like "Fight Club," the first rule of UFOs is "don't talk about the UFOs."
I don't currently have any equipment to do all-sky imaging. There are
several commercial sources and the pricing is from ~$10K to ~$100K. The
basic design is a fast off-the-shelf (f/2.8 or better) fisheye lens
combined with some carefully-designed fixed lenses to produce telecentric
rays through a bank of high-quality narrow-band interference filters (e.g.,
2-nm bandwidth at half-max, OD5 in the stop-band, usually with other
requirements on film quality, etc; very custom). The filters are between 2
and 4 inches in diameter, so the telecentric requirement is pretty
stringent for many designs to keep the filter wavelength from shifting
across the image. The filters are often selectable by a motorized
filterwheel. Then, there are some more custom fixed optics that focus the
telecentric rays back onto the imaging detector. The precise choice of
detector depends a lot on the science you're trying to do. My experience
has been predominantly with consumer astronomical CCDs and CMOS detectors
from Atik, SBIG, and Andor (a little better than "consumer-grade"). I'll
see if I can find pictures of some of the instrumentation for you if you'd
like to geek out on it.
The emissions we're looking at usually pretty faint and require long
integration (exposure) times to overcome measurement noise. The 630-nm
"red line" emission comes from an excited state of oxygen that's observed
in both the aurora and the airglow. Airglow is a by-product of the plasma
process of recombination, which is the reverse of production (ionization),
which is what the Sun does to create the ionosphere in the first place.
Red airglow comes from just below the peak plasma density of the F2 region,
about 250 km up. Green airglow (557.7 nm) is a brighter oxygen emission
and comes from the E region, about 97 km altitude. If you've seen
astronomical photos of waves in the night sky, these are probably green
airglow. This is also the photochemistry as the green aurora, although the
driving process is the magnetosphere, not diurnal recombination.
I've been "inside the fence" at Haleakala. I was a grad student at the
time and my advisor dropped into my office one day and said, "How do you
feel about going to Hawaii?" I responded affirmatively. The following
day, he came in and said, "How's Monday?" My host/minder was an USAF
contractor who had been an MP in Bosnia. The instrumentation (two separate
cameras) resided in several "huts" that could only be accessed by passing
through secure areas. The big dial locks on the doors made an impression
for sure. I don't think there would have been much "talking your way in,"
at least on the Air Force side. Their telescope can do things that the one
on the astronomy side can't. It moved really fast when they demo'ed it for
me. Of course, the night sky was amazing, too, with the clouds below you.
Did that scratch the itch? Now I'm getting wanderlust...
73,
--Ethan, K8GU.
On Mon, Jun 29, 2020 at 7:00 PM Tom Holmes via mvus-list <
mvus-list@lists.febo.com> wrote:
Ethan...
Cool video, but don’t understand why the UFO's are moving but not the
stars .
Can you talk more about the hardware you have to do this?
Have been to Haleakala a couple of times, but always had family so didn’t
make the effort to bluff my way into the observatory. Would have loved to
see it. I have been to Kitt's Peak in AZ, and to the VLA, both of which
quite fascinating, each in their own way.
Tom Holmes, N8ZM
-----Original Message-----
From: mvus-list mvus-list-bounces@lists.febo.com On Behalf Of Ethan
Miller K8GU via mvus-list
Sent: Monday, June 29, 2020 6:44 PM
To: Midwest VHF/UHF Society Mailing List mvus-list@lists.febo.com
Cc: Ethan Miller K8GU ethan@k8gu.com
Subject: Re: [mvus-list] Arecibo HF
Dana,
Cool. Yes, there's quite a bit of mutual coupling in this system!
I'm vaguely familiar with the source of the transmitters (I was
involved with putting a newer instrument at the location of the West
Coast counterpart), but have not gotten into the details of the feeds,
antennas, etc. It's neat to hear the backstory on the role that you
and Daun played!
Here is a link to a time-lapse movie taken at the Observatory (for
whatever reason, I can't lay my hands on data from the Culebra
instrument during heating right now). About 24 seconds into the
movie, you'll see a white spot in the center of the field of view
blinking ON and OFF. That's the HF.
http://k8gu.com/webpost/ao151109_6300.avi
http://k8gu.com/webpost/ao151109_6300.avi
I believe the Arecibo imager was only looking at the 630-nm emission
and my camera was configured for 557.7-nm, 589.3-nm, and OH broadband
in the near-IR. Because this is a filterwheel system, each additional
wavelength reduces temporal sampling. It becomes burdensome at the
four-minute exposures we were doing! In case you wondered, for some
reason, this imager is also out of focus. Mine was never that bad!
The Culebra site is quite good for the Caribbean, better than Arecibo,
but perhaps comparable to Bonaire, which is dry and not too overrun
with tourists and hotels. It is nothing like a number of other
optical sites where I've operated equipment, for example Cerro Tololo,
Chile, and Haleakala, Hawaii. I have not been to the new site that
they negotiated after the new management came in a couple of years
ago. I'll try to drag out some more heating imagery and see what I
have that I've never looked at. Believe it or not, my HF receiving
data from Culebra has been more interesting than the imagery so far.
We originally installed the imager to study a certain class of
traveling ionospheric disturbances that are pretty commonly observed
over Puerto Rico. There is a paper on this coming out in J. Geophys.
Res. soon, led by Pedrina Santos, of Arecibo.
The airport approach into CPX is pretty cool...going through that
little pass that's not-quite-aligned with the runway! My coworker and
I flew over on a Cape Air BN-2B Islander from SJU and had 4-5 Pelican
cases full of gear. The pilot very carefully balanced the plane
before we took off and I think we may have bumped another passenger.
That was a great trip.
73,
--Ethan, K8GU.
On Mon, Jun 29, 2020 at 5:42 PM Dana Whitlow via mvus-list
< mailto:mvus-list@lists.febo.com mvus-list@lists.febo.com> wrote:
What got me interested in "seeing" the light emission resulting from
Arecibo's HF system was in search of a better, more practical solution
problem of properly phasing the transmitters' outputs into their
in the array. I designed the multi-phase splitter for Arecibo while
there, and Daun pretty much built the whole thing hardware-wise. But
is that the dipoles talk to each other, and the driving impedance
dipole's feed point is not infinity, so radiation from each dipole
and phases of the currents in all the other dipoles, ad nauseum.
One option is careful system simulation, and I have put some effort
frankly it's not looking like a viable solution to me. Too many
guesses are involved. BTW, does anybody have a good Spice model for a
4CW150,000E power tetrode?
Another is direct measurement of the feed point complex currents with
coils (or similar sensors), but this is not trivial and would require
of significant funds in the sensors and in phase-matched cables running
the TX building. Nevertheless I suspect this is the best way.
Another, that is more economical, is to make all the transmission lines
integer number of half waves, and make the measurements at the TX end
cables. I worked out a way of doing the measurements with
of which sufficient extras came installed in the transmitters. I used
for trimming our feedlines to the same "length" (although they could
integer multiples of a half-wave), and it looked very promising. But
in actual operation requires building a bunch of additional
yet had the time or money to do so.
So, at present the technique used is to measure amplitude and phase of
wave (only) at the TX end of each line, basically by hand, and
transmitters' drive signals until we're happy with the results. This
working OK, but we don't know for sure, and it's a royal pain to do in
real problem is that this method does not really account for
dipoles, especially given that the transmitters' output are "power
impedance matched). BTW, does anybody have a good Spice model for a
The means for setting phases is via computer control of the stuff that
with a Python program written by another engineer (who has also left
But now, I can get to my other idea for optimizing phasing, which is to
emitted light in real time and crank on the "knobs" until the spot
most compact. It could even be done with a camera at a very remote
internet, thus allowing a camera location where the skies are really
Culebra site comes to mind for this.
On Sun, Jun 28, 2020 at 6:58 AM Ethan Miller K8GU via mvus-list <
Sorry I missed the MVUS showing of Arecibo photos. I had an HF
receiver and a relatively sensitive all-sky (fisheye) imager (the
imager is still there but operated by someone else now) in Culebra
a couple of years (for a different experiment) that was occasionally
repurposed for Arecibo HF experiments. It's pretty wild to see some
of the ionospheric structures they created with the HF system,
including airglow structures that were sub-visual magnitude blinking
on and off with the HF transmitter. Of course, at HAARP they've done
visual magnitude airglow, which does nothing to quell the conspiracy
I'm not a hard-core plasma physicist, but the stimulated RF emissions
from the Arecibo HF were also always interesting to see...the
high-power HF mode converts into plasma waves which interact with
other and some of them mode convert back into electromagnetic waves
different frequencies, shifted by "natural frequencies" (for example
the electron gyrofrequency) of the plasma. These are the types of
things that are theorized to be explanations for long-delayed echoes
(LDEs) and other radio oddities. I'll have to see if I have any data
floating around still that is clear and illustrative to a
technically-literate non-expert audience...
On Sun, Jun 28, 2020 at 1:56 AM Lenny via mvus-list
Just wondering if I can use the pictures and description in the Mt
VHF Radio Club ("The Packrats") newsletter. I'm sure the members
Please let me know either way.
--Lenny W2BVH (newsletter editor)
On 6/27/2020 4:28 PM, Daun Yeagley via mvus-list wrote:
It's "fun" trying to sort through all my pictures from Arecibo,
they are stored by date, and who knows what I was doing on a
Anyway, here are some pictures of the HF transmitters, and the
antennas in the bottom of the dish. For scale, look for the
that are standing in the opening in the middle. (that's where
hoist stuff up to the platform). Also, on the last one, if you
carefully you can see the cables that make up the secondary
Repair. Re-use. Re-purpose. Recycle.
Dana, et al,
They're anywhere from 0.5 nm to 3 nm bandwidth at half-max (FWHM).
The efficiency numbers vary from 50%-90% if I recall correctly.
Typical exposure times are 60 to 300 seconds per image. There are
some very sensitive and image-intensified auroral imagers and I
believe AFRL Space Vehicles have an airglow imager that approaches
video frame rates. But, these are an order of magnitude more
expensive and fiddly, as well as filling disks quickly. I referred to
my video as "time-lapse" but you may have missed that. The video I
sent is also very raw; typically, videos meant for public consumption
are annotated with metadata about date/time, wavelength, cardinal
directions, etc; they usually have the hot pixels and sometimes stars
(you should have seen Orion near the heater airglow) removed. The
images can also be "unwarped" onto a map, assuming the airglow
emanates from a uniform altitude.
The only time I had experience with 0.5-nm filters was for a
spacecraft instrument. We tuned it by varying the temperature of the
plate it was mounted in. The CTE of the filter material determined
the wavelength shift as we heated the mounting plate. To bring this
discussion full-circle, we used an ionospheric diagnostic mode
(incoherent scatter) of the ALTAIR radar in Kwajalein that Dave, K4TO,
mentioned as a part of the calibration effort for the primary portion
(a UV spectrograph) of that instrument. It had no problem tracking
the spacecraft. I simply used heavy clouds under full moon
illumination to cross-calibrate the visible photometers (that had the
aforementioned filters), though.
73,
--Ethan, K8GU.
On Mon, Jun 29, 2020 at 10:14 PM Dana Whitlow via mvus-list
<mvus-list@lists.febo.com> wrote:
>
> Ethan,
>
> What is the bandwidth of typical filters used in upper atmosphere
> studies?
>
> You've made a couple of references to long time exposures. Yet
> watching the videos of Arecibo-driven light emission while I was
> there gave me the distinct impression that this was normal video
> at normal frame rates. Was that just wishful thinking on my part?
>
> Note that I've not yet watched the video you attached- the only
> PC I have that *may* be able to play AVI format is rather busy at the
> moment doing other things.
>
> Dana
>
>
> On Mon, Jun 29, 2020 at 8:59 PM Ethan Miller K8GU via mvus-list <
> mvus-list@lists.febo.com> wrote:
>
> > Tom,
> >
> > Like "Fight Club," the first rule of UFOs is "don't talk about the UFOs."
> >
> > I don't currently have any equipment to do all-sky imaging. There are
> > several commercial sources and the pricing is from ~$10K to ~$100K. The
> > basic design is a fast off-the-shelf (f/2.8 or better) fisheye lens
> > combined with some carefully-designed fixed lenses to produce telecentric
> > rays through a bank of high-quality narrow-band interference filters (e.g.,
> > 2-nm bandwidth at half-max, OD5 in the stop-band, usually with other
> > requirements on film quality, etc; very custom). The filters are between 2
> > and 4 inches in diameter, so the telecentric requirement is pretty
> > stringent for many designs to keep the filter wavelength from shifting
> > across the image. The filters are often selectable by a motorized
> > filterwheel. Then, there are some more custom fixed optics that focus the
> > telecentric rays back onto the imaging detector. The precise choice of
> > detector depends a lot on the science you're trying to do. My experience
> > has been predominantly with consumer astronomical CCDs and CMOS detectors
> > from Atik, SBIG, and Andor (a little better than "consumer-grade"). I'll
> > see if I can find pictures of some of the instrumentation for you if you'd
> > like to geek out on it.
> >
> > The emissions we're looking at usually pretty faint and require long
> > integration (exposure) times to overcome measurement noise. The 630-nm
> > "red line" emission comes from an excited state of oxygen that's observed
> > in both the aurora and the airglow. Airglow is a by-product of the plasma
> > process of recombination, which is the reverse of production (ionization),
> > which is what the Sun does to create the ionosphere in the first place.
> > Red airglow comes from just below the peak plasma density of the F2 region,
> > about 250 km up. Green airglow (557.7 nm) is a brighter oxygen emission
> > and comes from the E region, about 97 km altitude. If you've seen
> > astronomical photos of waves in the night sky, these are probably green
> > airglow. This is also the photochemistry as the green aurora, although the
> > driving process is the magnetosphere, not diurnal recombination.
> >
> > I've been "inside the fence" at Haleakala. I was a grad student at the
> > time and my advisor dropped into my office one day and said, "How do you
> > feel about going to Hawaii?" I responded affirmatively. The following
> > day, he came in and said, "How's Monday?" My host/minder was an USAF
> > contractor who had been an MP in Bosnia. The instrumentation (two separate
> > cameras) resided in several "huts" that could only be accessed by passing
> > through secure areas. The big dial locks on the doors made an impression
> > for sure. I don't think there would have been much "talking your way in,"
> > at least on the Air Force side. Their telescope can do things that the one
> > on the astronomy side can't. It moved really fast when they demo'ed it for
> > me. Of course, the night sky was amazing, too, with the clouds below you.
> >
> > Did that scratch the itch? Now I'm getting wanderlust...
> >
> > 73,
> >
> > --Ethan, K8GU.
> >
> >
> >
> > On Mon, Jun 29, 2020 at 7:00 PM Tom Holmes via mvus-list <
> > mvus-list@lists.febo.com> wrote:
> >
> > > Ethan...
> > >
> > >
> > >
> > > Cool video, but don’t understand why the UFO's are moving but not the
> > > stars .
> > >
> > >
> > >
> > > Can you talk more about the hardware you have to do this?
> > >
> > >
> > >
> > > Have been to Haleakala a couple of times, but always had family so didn’t
> > > make the effort to bluff my way into the observatory. Would have loved to
> > > see it. I have been to Kitt's Peak in AZ, and to the VLA, both of which
> > are
> > > quite fascinating, each in their own way.
> > >
> > >
> > >
> > > Tom Holmes, N8ZM
> > >
> > >
> > >
> > > -----Original Message-----
> > > From: mvus-list <mvus-list-bounces@lists.febo.com> On Behalf Of Ethan
> > > Miller K8GU via mvus-list
> > > Sent: Monday, June 29, 2020 6:44 PM
> > > To: Midwest VHF/UHF Society Mailing List <mvus-list@lists.febo.com>
> > > Cc: Ethan Miller K8GU <ethan@k8gu.com>
> > > Subject: Re: [mvus-list] Arecibo HF
> > >
> > >
> > >
> > > Dana,
> > >
> > >
> > >
> > > Cool. Yes, there's quite a bit of mutual coupling in this system!
> > >
> > > I'm vaguely familiar with the source of the transmitters (I was
> > >
> > > involved with putting a newer instrument at the location of the West
> > >
> > > Coast counterpart), but have not gotten into the details of the feeds,
> > >
> > > antennas, etc. It's neat to hear the backstory on the role that you
> > >
> > > and Daun played!
> > >
> > >
> > >
> > > Here is a link to a time-lapse movie taken at the Observatory (for
> > >
> > > whatever reason, I can't lay my hands on data from the Culebra
> > >
> > > instrument during heating right now). About 24 seconds into the
> > >
> > > movie, you'll see a white spot in the center of the field of view
> > >
> > > blinking ON and OFF. That's the HF.
> > >
> > >
> > >
> > > <http://k8gu.com/webpost/ao151109_6300.avi>
> > > http://k8gu.com/webpost/ao151109_6300.avi
> > >
> > >
> > >
> > > I believe the Arecibo imager was only looking at the 630-nm emission
> > >
> > > and my camera was configured for 557.7-nm, 589.3-nm, and OH broadband
> > >
> > > in the near-IR. Because this is a filterwheel system, each additional
> > >
> > > wavelength reduces temporal sampling. It becomes burdensome at the
> > >
> > > four-minute exposures we were doing! In case you wondered, for some
> > >
> > > reason, this imager is also out of focus. Mine was never that bad!
> > >
> > >
> > >
> > > The Culebra site is quite good for the Caribbean, better than Arecibo,
> > >
> > > but perhaps comparable to Bonaire, which is dry and not too overrun
> > >
> > > with tourists and hotels. It is nothing like a number of other
> > >
> > > optical sites where I've operated equipment, for example Cerro Tololo,
> > >
> > > Chile, and Haleakala, Hawaii. I have not been to the new site that
> > >
> > > they negotiated after the new management came in a couple of years
> > >
> > > ago. I'll try to drag out some more heating imagery and see what I
> > >
> > > have that I've never looked at. Believe it or not, my HF receiving
> > >
> > > data from Culebra has been more interesting than the imagery so far.
> > >
> > >
> > >
> > > We originally installed the imager to study a certain class of
> > >
> > > traveling ionospheric disturbances that are pretty commonly observed
> > >
> > > over Puerto Rico. There is a paper on this coming out in J. Geophys.
> > >
> > > Res. soon, led by Pedrina Santos, of Arecibo.
> > >
> > >
> > >
> > > The airport approach into CPX is pretty cool...going through that
> > >
> > > little pass that's not-quite-aligned with the runway! My coworker and
> > >
> > > I flew over on a Cape Air BN-2B Islander from SJU and had 4-5 Pelican
> > >
> > > cases full of gear. The pilot very carefully balanced the plane
> > >
> > > before we took off and I think we may have bumped another passenger.
> > >
> > > That was a great trip.
> > >
> > >
> > >
> > > 73,
> > >
> > >
> > >
> > > --Ethan, K8GU.
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > On Mon, Jun 29, 2020 at 5:42 PM Dana Whitlow via mvus-list
> > >
> > > < <mailto:mvus-list@lists.febo.com> mvus-list@lists.febo.com> wrote:
> > >
> > > >
> > >
> > > > Ethan,
> > >
> > > >
> > >
> > > > What got me interested in "seeing" the light emission resulting from
> > >
> > > > operation of
> > >
> > > > Arecibo's HF system was in search of a better, more practical solution
> > to
> > >
> > > > the
> > >
> > > > problem of properly phasing the transmitters' outputs into their
> > > respective
> > >
> > > > dipoles
> > >
> > > > in the array. I designed the multi-phase splitter for Arecibo while
> > > still
> > >
> > > > employed
> > >
> > > > there, and Daun pretty much built the whole thing hardware-wise. But
> > > the
> > >
> > > > problem
> > >
> > > > is that the dipoles talk to each other, and the driving impedance
> > > presented
> > >
> > > > to each
> > >
> > > > dipole's feed point is not infinity, so radiation from each dipole
> > >
> > > > affects the amplitudes
> > >
> > > > and phases of the currents in all the other dipoles, ad nauseum.
> > >
> > > >
> > >
> > > > One option is careful system simulation, and I have put some effort
> > into
> > >
> > > > this, but
> > >
> > > > frankly it's not looking like a viable solution to me. Too many
> > >
> > > > imponderables and
> > >
> > > > guesses are involved. BTW, does anybody have a good Spice model for a
> > >
> > > > 4CW150,000E power tetrode?
> > >
> > > >
> > >
> > > > Another is direct measurement of the feed point complex currents with
> > >
> > > > Rogowski
> > >
> > > > coils (or similar sensors), but this is not trivial and would require
> > the
> > >
> > > > expenditure
> > >
> > > > of significant funds in the sensors and in phase-matched cables running
> > >
> > > > back to
> > >
> > > > the TX building. Nevertheless I suspect this is the best way.
> > >
> > > >
> > >
> > > > Another, that is more economical, is to make all the transmission lines
> > > an
> > >
> > > > exact
> > >
> > > > integer number of half waves, and make the measurements at the TX end
> > of
> > > the
> > >
> > > > cables. I worked out a way of doing the measurements with
> > > dual-directional
> > >
> > > > couplers,
> > >
> > > > of which sufficient extras came installed in the transmitters. I used
> > > this
> > >
> > > > basic technique
> > >
> > > > for trimming our feedlines to the same "length" (although they could
> > > differ
> > >
> > > > in length by
> > >
> > > > integer multiples of a half-wave), and it looked very promising. But
> > > using
> > >
> > > > the technique
> > >
> > > > in actual operation requires building a bunch of additional
> > electronics,
> > >
> > > > and nobody has
> > >
> > > > yet had the time or money to do so.
> > >
> > > >
> > >
> > > > So, at present the technique used is to measure amplitude and phase of
> > > the
> > >
> > > > *forward*
> > >
> > > > *wave* (only) at the TX end of each line, basically by hand, and
> > >
> > > > iteratively tweak on the
> > >
> > > > transmitters' drive signals until we're happy with the results. This
> > >
> > > > actually *seems* to be
> > >
> > > > working OK, but we don't know for sure, and it's a royal pain to do in
> > > any
> > >
> > > > case. The
> > >
> > > > real problem is that this method does not really account for
> > interactions
> > >
> > > > between the
> > >
> > > > dipoles, especially given that the transmitters' output are "power
> > >
> > > > matched", (not
> > >
> > > > impedance matched). BTW, does anybody have a good Spice model for a
> > >
> > > > 4CW150,000E
> > >
> > > > power tetrode?
> > >
> > > >
> > >
> > > > The means for setting phases is via computer control of the stuff that
> > > Daun
> > >
> > > > put together,
> > >
> > > > with a Python program written by another engineer (who has also left
> > the
> > >
> > > > observatory).
> > >
> > > >
> > >
> > > > But now, I can get to my other idea for optimizing phasing, which is to
> > >
> > > > view the spot of
> > >
> > > > emitted light in real time and crank on the "knobs" until the spot
> > > becomes
> > >
> > > > brightest and
> > >
> > > > most compact. It could even be done with a camera at a very remote
> > >
> > > > location via the
> > >
> > > > internet, thus allowing a camera location where the skies are really
> > > dark.
> > >
> > > > Naturally the
> > >
> > > > Culebra site comes to mind for this.
> > >
> > > >
> > >
> > > > Dana
> > >
> > > >
> > >
> > > >
> > >
> > > > On Sun, Jun 28, 2020 at 6:58 AM Ethan Miller K8GU via mvus-list <
> > >
> > > > <mailto:mvus-list@lists.febo.com> mvus-list@lists.febo.com> wrote:
> > >
> > > >
> > >
> > > > > Daun/Dana,
> > >
> > > > >
> > >
> > > > > Sorry I missed the MVUS showing of Arecibo photos. I had an HF
> > >
> > > > > receiver and a relatively sensitive all-sky (fisheye) imager (the
> > >
> > > > > imager is still there but operated by someone else now) in Culebra
> > for
> > >
> > > > > a couple of years (for a different experiment) that was occasionally
> > >
> > > > > repurposed for Arecibo HF experiments. It's pretty wild to see some
> > >
> > > > > of the ionospheric structures they created with the HF system,
> > >
> > > > > including airglow structures that were sub-visual magnitude blinking
> > >
> > > > > on and off with the HF transmitter. Of course, at HAARP they've done
> > >
> > > > > visual magnitude airglow, which does nothing to quell the conspiracy
> > >
> > > > > theories!
> > >
> > > > >
> > >
> > > > > I'm not a hard-core plasma physicist, but the stimulated RF emissions
> > >
> > > > > from the Arecibo HF were also always interesting to see...the
> > >
> > > > > high-power HF mode converts into plasma waves which interact with
> > each
> > >
> > > > > other and some of them mode convert back into electromagnetic waves
> > at
> > >
> > > > > different frequencies, shifted by "natural frequencies" (for example
> > >
> > > > > the electron gyrofrequency) of the plasma. These are the types of
> > >
> > > > > things that are theorized to be explanations for long-delayed echoes
> > >
> > > > > (LDEs) and other radio oddities. I'll have to see if I have any data
> > >
> > > > > floating around still that is clear and illustrative to a
> > >
> > > > > technically-literate non-expert audience...
> > >
> > > > >
> > >
> > > > > 73,
> > >
> > > > >
> > >
> > > > > --Ethan, K8GU.
> > >
> > > > >
> > >
> > > > > On Sun, Jun 28, 2020 at 1:56 AM Lenny via mvus-list
> > >
> > > > > < <mailto:mvus-list@lists.febo.com> mvus-list@lists.febo.com> wrote:
> > >
> > > > > >
> > >
> > > > > > Hi Daun
> > >
> > > > > >
> > >
> > > > > > Just wondering if I can use the pictures and description in the Mt
> > > Airy
> > >
> > > > > > VHF Radio Club ("The Packrats") newsletter. I'm sure the members
> > > would
> > >
> > > > > > be interested.
> > >
> > > > > >
> > >
> > > > > > Please let me know either way.
> > >
> > > > > >
> > >
> > > > > > Tnx, 73 & stay safe,
> > >
> > > > > >
> > >
> > > > > > --Lenny W2BVH (newsletter editor)
> > >
> > > > > >
> > >
> > > > > >
> > >
> > > > > >
> > >
> > > > > > On 6/27/2020 4:28 PM, Daun Yeagley via mvus-list wrote:
> > >
> > > > > > > It's "fun" trying to sort through all my pictures from Arecibo,
> > as
> > >
> > > > > > > they are stored by date, and who knows what I was doing on a
> > >
> > > > > > > particular day!
> > >
> > > > > > >
> > >
> > > > > > > Anyway, here are some pictures of the HF transmitters, and the
> > >
> > > > > > > antennas in the bottom of the dish. For scale, look for the
> > guys
> > >
> > > > > > > that are standing in the opening in the middle. (that's where
> > they
> > >
> > > > > > > hoist stuff up to the platform). Also, on the last one, if you
> > > look
> > >
> > > > > > > carefully you can see the cables that make up the secondary
> > > reflector.
> > >
> > > > > > >
> > >
> > > > > > > Daun
> > >
> > > > > > >
> > >
> > > > > > >
> > >
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> > >
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> > > > >
> > >
> > > > >
> > >
> > > > >
> > >
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> > >
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