Details for Benchmark: HT0717
N 37° 48.400 W 122° 25.650 (NAD 83)
Coordinates may not be exact. Altitude is ADJUSTED and location is SCALED. (more info)
- In SAN FRANCISCO county, CA View Original Datasheet
- U 108
- Marker Type:
- bench mark disk
- massive structures
- Probably hold position/elevation well.
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Documented History (by the NGS)
|1/1/1932 by CGS (MONUMENTED)
|1/1/1952 by NGS (GOOD)
|DESCRIBED BY NATIONAL GEODETIC SURVEY 1952
AT SAN FRANCISCO. AT SAN FRANCISCO, AT FORT MASON, NORTH OF AND IN LINE WITH THE WEST END OF BUILDING T-241, IN THE TOP OF THE CONCRETE ROOF OF AN OLD GUN EMPLACEMENT (BUILDING NO. 242), 86 FEET NORTH OF THE CENTER LINE OF FUNSTON STREET, 16.7 FEET NORTH OF THE SOUTHWEST CORNER OF THE ROOF, 0.9 FOOT EAST OF THE WEST EDGE, AND ABOUT 2 FEET HIGHER THAN THE STREET.
|1/1/1969 by NGS (GOOD)
|RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1969
RECOVERED IN GOOD CONDITION.
|9/16/1988 by NGS (GOOD)
|RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1988
RECOVERED IN GOOD CONDITION WITH THE FOLLOWING EXCEPTIONS. ADD--0.5 M (1.6 FT) SOUTH OF A FENCE. NOTE--BUILDING T 241 MENTIONED IN THE ORIGINAL DESCRIPTION IS NOW BUILDING NUMBER 241-E.
- The horizontal coordinates were scaled from a topographic map and have an estimated accuracy of +/- 6 seconds.
- The orthometric height was determined by differential leveling and adjusted by the National Geodetic Survey in June 1991.
- The geoid height was determined by GEOID99.
- The dynamic height is computed by dividing the NAVD 88 geopotential number by the normal gravity value computed on the Geodetic Reference System of 1980 (GRS 80) ellipsoid at 45 degrees latitude (G = 980.6199 gals.).
- The modeled gravity was interpolated from observed gravity values.