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Details for Benchmark: HV1842

N 38° 53.333 W 077° 02.100 (NAD 83)

Altitude: 40.43

Coordinates may not be exact. Altitude is ADJUSTED and location is SCALED. (more info)

Location:
In DISTRICT OF COLUMBIA county, DC View Original Datasheet
Designation:
C 1
Marker Type:
survey disk
Setting:
light structures
Stability:
Mark of questionable or unknown stability.

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The listing has this one as being destroyed, a bit obvious it will not be here.

Documented History (by the NGS)

01/01/1923 by CGS (MONUMENTED)
01/01/1971 by NGS (GOOD)
DESCRIBED BY NATIONAL GEODETIC SURVEY 1971 AT WASHINGTON. AT WASHINGTON, D.C., AT THE WASHINGTON MONUMENT, SET IN THE TOP OF THE NORTH END OF THE GRANITE DOORSILL ON THE EAST SIDE OF THE MONUMENT, 12 INCHES SOUTH OF A CONCRETE WALL, AND 8 INCHES ABOVE THE LANDING AT THE ENTRANCE TO THE MONUMENT. NOTE-- THERE IS A DOOR ABOVE THE MARK WHICH CAN BE PUSHED ASIDE IN ORDER TO PLUMB THE ROD.
01/01/1974 by NGS (GOOD)
RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1974 RECOVERED IN GOOD CONDITION.
05/12/1992 by NGS (MARK NOT FOUND)
RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1992 PARK RANGERS STATED THE MARK HAD BEEN DESTROYED.

Control Text

  • 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.

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