NA2011 - National Adjustment 2011 in 2013 Documents
The National Adjustment of 2011
As part of continuing efforts to improve the National Spatial Reference System (NSRS), on June 30, 2012, NGS completed the National Adjustment of 2011 Project. The National Adjustment of 2011 Project is abbreviated "NA2011 Project" or "NA2011”. This project was a nationwide adjustment of NGS "passive" control (physical marks that can be occupied with survey equipment, such as brass disk bench marks) positioned using Global Navigation Satellite System (GNSS) technology. The adjustment was constrained to current North American Datum of 1983 (NAD 83) latitude, longitude, and ellipsoid heights of NGS Continuously Operating Reference Stations (CORS). The CORS network is an "active" control system consisting of permanently mounted GNSS antennas, and it is the geometric foundation of the NSRS. Constraining the adjustment to the CORS optimally aligned the GNSS passive control with the active control, providing a unified reference frame to serve the nation's geometric positioning needs.