Details for Benchmark: HV1400
N 38° 52.417 W 076° 59.683 (NAD 83)
Coordinates may not be exact. Altitude is ADJUSTED and location is SCALED. (more info)
- In DISTRICT OF COLUMBIA county, DC View Original Datasheet
- Marker Type:
- bench mark disk
- light structures
- Mark of questionable or unknown stability.
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Documented History (by the NGS)
|Unknown by CGS (MONUMENTED)
|01/01/1923 by CGS (GOOD)
|DESCRIBED BY COAST AND GEODETIC SURVEY 1923
IN WASHINGTON. IN SOUTHEAST WASHINGTON, ON THE GROUNDS OF THE NAVAL GUN FACTORY, NEAR THE NORTHEAST CORNER OF THE INTERSECTION OF DAHLGREN AVENUE AND MONTGOMERY SQUARE, ON THE WEST SIDE OF BUILDING 108, IN THE FIRST DOORWAY FROM THE SOUTH END OF THE BUILDING, IN THE GRANITE DOORSILL, 0.9 FOOT WEST OF THE DOOR, AND 0.3 FOOT NORTH OF THE SOUTH END OF THE DOORWAY. A STANDARD DISK, STAMPED X.
|01/01/1955 by CGS (GOOD)
|RECOVERY NOTE BY COAST AND GEODETIC SURVEY 1955
RECOVERED IN GOOD CONDITION.
- 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.
- This Tidal Bench Mark is designated as VM 12745 by the Center for Operational Oceanographic Products and Services.
- 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.