Are derived transformations available relating successive versions of NAD 83 (199X) to each other?
Program NADCON has been updated after each statewide readjustment to account for the shifts due to the HARN upgrade. (Contact Cindy Craig.) • I have heard rumors of a new reference system/datum. What are NGS’s plans? Between 1987 and 1997, the National Geodetic Survey, in cooperation with other Federal, State and local surveying agencies has conducted a resurvey of the United States using Global Positioning System (GPS) observations often referred to as the High Accuracy Reference Networks (HARNs). All 50 states, American Samoa, Guam, Puerto Rico and the Virgin Islands have now been connected with a network of A-order and B-order horizontal control points. Continued improvements in GPS technology and requirements from users of spatial data will eventually require a transition to an improve global reference frame based on the International Terrestrial Reference Frame (ITRF). Positions relative to ITRF differ from the existing North American Datum of 1983 (NAD 83) by approximately 1 mete
