Details for Benchmark: AE9189
N 41° 47.800 W 091° 38.550 (NAD 83)
Coordinates may not be exact. Altitude is ADJUSTED and location is SCALED. (more info)
- In JOHNSON county, IA View Original Datasheet
- F 550.3
- Marker Type:
- bench mark disk
- set into the top of a metal pipe driven into the ground
- Mark of questionable or unknown stability.
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Documented History (by the NGS)
|01/01/1980 by USE (MONUMENTED)
|01/08/1998 by NGS (GOOD)
|DESCRIBED BY NATIONAL GEODETIC SURVEY 1998 (GAS)
1.3 KM (0.80 MI) NORTHWESTERLY ALONG NORTH DUBUQUE STREET FROM THE POST OFFICE IN NORTH LIBERTY, THENCE 5.3 KM (3.30 MI) NORTHERLY ALONG STATE HIGHWAY 965, 39.2 M (128.6 FT) SOUTHEAST OF A UTILITY POLE, 31.2 M (102.4 FT) NORTHEAST OF THE HIGHWAY CENTERLINE, 17.3 M (56.8 FT) NORTHEAST OF THE NORTHWEST END OF A CULVERT UNDER CURTIS BRIDGE ROAD, 13.9 M (45.6 FT) NORTHWEST OF THE ROAD CENTER, 1.0 M (3.3 FT) BELOW THE LEVEL OF THE HIGHWAY, AND 0.1 M (0.3 FT) NORTH OF A WITNESS POST. NOTE--THE DISK IS ENCASED IN A METAL PIPE AND IS FLUSH WITH THE GROUND SURFACE.
- 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 September 2000.
- 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.