Details for Benchmark: LC1681
N 40° 20.700 W 088° 45.333 (NAD 83)
Coordinates may not be exact. Altitude is ADJUSTED and location is SCALED. (more info)
- In MCLEAN county, IL View Original Datasheet
- E 297
- Marker Type:
- metal rod
- stainless steel rod
- Probably hold position/elevation well.
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Documented History (by the NGS)
|01/01/1986 by NGS (MONUMENTED)
|DESCRIBED BY NATIONAL GEODETIC SURVEY 1986
IN LEROY. IN LEROY, AT THE INTERSECTION OF U.S. HIGHWAY 150 (EAST CEDAR STREET) AND SOUTH BARNETT STREET, 14.1 M (46.3 FT) NORTHWEST OF THE NORTHWEST CORNER OF A HOUSE AT 601 EAST CEDAR, 8.3 M (27.2 FT) EAST OF THE CENTER OF THE STREET, 6.6 M (21.7 FT) SOUTH OF THE CENTERLINE OF THE HIGHWAY, 1.3 M (4.3 FT) SOUTHWEST OF A NO PARKING SIGN, AND 1.0 M (3.3 FT) EAST OF A UTILITY POLE. NOTE--ACCESS TO DATUM POINT IS HAD THROUGH A 5-INCH LOGO CAP. THE MARK IS 0.2 M BELOW THE HIGHWAY.
- 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.