National Geodetic Survey Bench Mark
Hello, TimeNutters--
Majdi asked about details on the USGS benchmark located
about 1/2 mile from my house out here in the boonies.
Below is what I have in my file on it.
Some of this means nothing to me-- my only interest in the
benchmark was knowing (roughly) how accurately it is located
for comparing to my GPS and GPSDO receivers.
Mike Baker
N 29d 32m 31.00741s (which is 31s plus 0.75ft)
W 082d 21m 04.77943s (which is 04s plus 68.84ft)
Parked truck immediately beside the (apparent) marker location
and got the following readings:
N 29d 32.519m (translates to: 32m 31.14s or 31s plus 14.12ft)
W 82d 21.078m (translates to: 21m 04.92s or 04s plus 60.06ft)
At this location, each sec north = 100.83ft each sec west = 88.33ft
Look for a cap and nail (small disk) on the centerline of the road,
or some sort of marker post by the southwest side of the road.
If you find the marker post, the benchmark is 7.5 feet south of it,
and pretty much next to the cap and nail in the road centerline.
It will be between the driveways for 1926 SE Wacahoota Road and
2010 SE Wacahoota Road.
THE STATION IS A STANDARD AC GIS DISK STAMPED---STATION A107---,
SET IN THE GROUND 15 FT TO REFUSAL (6 IN PVC SLEEVE) 9.83 METERS
(32.24 FT) SOUTHWEST FROM A NAIL & CAP (NO 3765) SET
IN CENTERLINE OF ACR 18,
51.17 METERS (167.87 FT) NORTHWEST FROM A NAIL & CAP (NO 3765)
SET IN POWER POLE,
2.3 METERS (7.5 FT) SOUTH OF CARSONITE POST SET,
31.82 METERS (104.40 FT) SOUTHEAST FROM A NAIL & CAP (NO 3765)
SET IN A POWER POLE,
7.96 METERS (26.13 FT) NORTHEAST FROM A REBAR & CAP (NO 3765) SET.
AZIMUTH MARK NO. 1 IS A STANDARD AC GIS DISK STAMPED---AZIMUTH A108---,
SET INTO GROUND 10.5 FT TO REFUSAL (6 IN PVC SLEEVE)
5.95 METERS (19.52 FT) NORTHWEST FROM A NAIL & CAP (NO 3765) SET
IN POWER POLE,
9.58 METERS (31.43 FT) SOUTH FROM A NAIL & CAP (NO 3765) SET IN
CENTERLINE OF ACR 18.
TO REACH THE AZIMUTH FROM THE STATION, GO NORTHWEST FOR
0.5 KM (0.3 MI) ON ACR 18 TO AZIMUTH MARK ON THE SOUTH SIDE OF ROAD.
STATION RECOVERY (2002)
RECOVERY NOTE BY FL DEPT OF ENV PRO 2002 (BPJ)
THE MARK IS ABOUT 4.6 MI NORTHWEST OF MICANOPY, IN SECTION 18,
TOWNSHIP 11 SOUTH, RANGE 20 EAST.
A DISC & METAL ROD COMBINATION RECESSED 0.3 FT BELOW THE LEVEL
OF THE GROUND AND LEVEL WITH SOUTHEAST WACAHOOTA ROAD.
LOCATED 122.0 FT EAST-SOUTHEAST OF THE EXTENDED APPROXIMATE
CENTERLINE OF A DIRT DRIVEWAY AT 2010 SOUTHEAST WACAHOOTA
ROAD, 108.0 FT WEST-NORTHWEST OF THE EXTENDED APPROXIMATE
CENTERLINE OF A DIRT DRIVEWAY AT 1926 SOUTHEAST WACAHOOTA
ROAD, 32.3 FT SOUTH-SOUTHWEST OF THE APPROXIMATE CENTERLINE
OF SOUTHEAST WACAHOOTA ROAD, 7.8 FT SOUTH-SOUTHWEST OF A
BARB WIRE FENCE & 7.7 FT SOUTH-SOUTHWEST OF A CARSONITE
WITNESS POST.
NOTE A BAR MAGNET WAS EMBEDDED IN THE MONUMENT.
NOTE 6-INCH PVC SLEEVE AROUND THE DISC IS DAMAGED
BUT DISC IS IN GOOD CONDITION.
The NGS Data Sheet
See file dsdata.txt for more information about the datasheet.
DATABASE = ,PROGRAM = datasheet, VERSION = 7.61
1 National Geodetic Survey, Retrieval Date = SEPTEMBER 4, 2008
AR1764
AR1764 DESIGNATION - A 107
AR1764 PID - AR1764
AR1764 STATE/COUNTY- FL/ALACHUA
AR1764 USGS QUAD - MICANOPY (1988)
AR1764
AR1764 *CURRENT SURVEY CONTROL
AR1764
AR1764* NAD 83(2007)- 29 32 31.00741(N) 082 21 04.77943(W)
ADJUSTED
AR1764* NAVD 88 - 29.117 (meters) 95.53 (feet)
ADJUSTED
AR1764
AR1764 EPOCH DATE - 2002.00
AR1764 X - 739,157.689 (meters) COMP
AR1764 Y - -5,504,058.842 (meters) COMP
AR1764 Z - 3,126,301.264 (meters) COMP
AR1764 LAPLACE CORR- -0.46 (seconds)
DEFLEC99
AR1764 ELLIP HEIGHT- 1.257 (meters) (02/10/07)
ADJUSTED
AR1764 GEOID HEIGHT- -27.78 (meters) GEOID03
AR1764 DYNAMIC HT - 29.077 (meters) 95.40 (feet) COMP
AR1764
AR1764 ------- Accuracy Estimates (at 95% Confidence Level in cm)
AR1764 Type PID Designation North East
Ellip
AR1764
AR1764 NETWORK AR1764 A 107 2.12 1.43
4.21
AR1764
AR1764 MODELED GRAV- 979,275.5 (mgal) NAVD 88
AR1764
AR1764 VERT ORDER - SECOND CLASS I
AR1764
AR1764.The horizontal coordinates were established by GPS observations
AR1764.and adjusted by the National Geodetic Survey in February 2007.
AR1764
AR1764.The datum tag of NAD 83(2007) is equivalent to NAD 83(NSRS2007).
AR1764.See National Readjustment for more information.
AR1764.The horizontal coordinates are valid at the epoch date displayed
above.
AR1764.The epoch date for horizontal control is a decimal equivalence
AR1764.of Year/Month/Day.
AR1764
AR1764.The orthometric height was determined by differential leveling
AR1764.and adjusted in May 2004.
AR1764.No vertical observational check was made to the station.
AR1764
AR1764.The X, Y, and Z were computed from the position and the
ellipsoidal
ht.
AR1764
AR1764.The Laplace correction was computed from DEFLEC99 derived
deflections.
AR1764
AR1764.The ellipsoidal height was determined by GPS observations
AR1764.and is referenced to NAD 83.
AR1764
AR1764.The geoid height was determined by GEOID03.
AR1764
AR1764.The dynamic height is computed by dividing the NAVD 88
AR1764.geopotential number by the normal gravity value computed on the
AR1764.Geodetic Reference System of 1980 (GRS 80) ellipsoid at 45
AR1764.degrees latitude (g = 980.6199 gals.).
AR1764
AR1764.The modeled gravity was interpolated from observed gravity values.
AR1764
AR1764; North East Units Scale Factor
Converg.
AR1764;SPC FL N - 62,036.260 808,252.110 MT 1.00000756
+1 04
47.1
AR1764;SPC FL N - 203,530.63 2,651,740.46 sFT 1.00000756
+1 04
47.1
AR1764;UTM 17 - 3,268,792.469 369,066.923 MT 0.99981153
-0 39
59.0
AR1764
AR1764! - Elev Factor x Scale Factor = Combined Factor
AR1764!SPC FL N - 0.99999980 x 1.00000756 = 1.00000736
AR1764!UTM 17 - 0.99999980 x 0.99981153 = 0.99981133
AR1764
AR1764 SUPERSEDED SURVEY CONTROL
AR1764
AR1764 NAD 83(1999)- 29 32 31.00761(N) 082 21 04.77971(W)
AD( ) 2
AR1764 ELLIP H (06/12/02) 1.228 (m)
GP( ) 4
1
AR1764 NAD 83(1990)- 29 32 31.00634(N) 082 21 04.77939(W)
AD( ) 2
AR1764 ELLIP H (05/01/91) 1.267 (m)
GP( ) 4
1
AR1764 NAD 83(1986)- 29 32 31.01433(N) 082 21 04.78738(W)
AD( ) 2
AR1764 NGVD 29 (11/17/89) 29.7 (m) 97. (f) GPS OBS
AR1764
AR1764.Superseded values are not recommended for survey control.
AR1764.NGS no longer adjusts projects to the NAD 27 or NGVD 29 datums.
AR1764.See file dsdata.txt to determine how the superseded data were
derived.
AR1764
AR1764_U.S. NATIONAL GRID SPATIAL ADDRESS: 17RLN6906768792(NAD 83)
AR1764_MARKER: DD = SURVEY DISK
AR1764_SETTING: 2 = OBJECT DRIVEN INTO GROUND
AR1764_SP_SET: OBJECT DRIVEN INTO GROUND
AR1764_STAMPING: A107
AR1764_MARK LOGO: FL-001
AR1764_MAGNETIC: M = MARKER EQUIPPED WITH BAR MAGNET
AR1764_STABILITY: D = MARK OF QUESTIONABLE OR UNKNOWN STABILITY
AR1764_SATELLITE: THE SITE LOCATION WAS REPORTED AS SUITABLE FOR
AR1764+SATELLITE: SATELLITE OBSERVATIONS - October 31, 2002
AR1764
AR1764 HISTORY - Date Condition Report By
AR1764 HISTORY - 1988 MONUMENTED PMC
AR1764 HISTORY - 20021031 GOOD FLDEP