Details for Benchmark: JC1156
N 38° 40.933 W 090° 10.983 (NAD 83)
Coordinates may not be exact. Altitude is ADJUSTED and location is SCALED. (more info)
- In MADISON county, IL View Original Datasheet
- X 283
- Marker Type:
- metal rod
- stainless steel rod
- Probably hold position/elevation well.
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Documented History (by the NGS)
|01/01/1981 by NGS (MONUMENTED)
|DESCRIBED BY NATIONAL GEODETIC SURVEY 1981
IN NEWPORT. IN NEWPORT, ALONG THE TOP OF THE MAIN LEVEE NEAR THE MILITARY RESERVATION, 0.7 KILOMETERS (0.45 MILES) NORTH OF THE MERCHANTS BRIDGE, AT A GRAVEL ROAD CROSSING THE LEVEE, 3.35 METERS (11.0 FEET) EAST-NORTHEAST OF THE CENTER OF THE ROAD ALONG THE TOP OF THE LEVEE, 0.45 METERS (1.5 FEET) NORTH-NORTHWEST OF A METAL WITNESS POST. THE MARK IS 0.39 METERS SSE FROM A WITNESS POST. THE MARK IS 0.2 M BELOW TOP OF LEVEE.
- 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.