National Geodetic Survey: Who We Are

A Federal Base Network (FBN) control point is a stable, monumented point whose location is used as a basis for obtaining locations of other points. FBN points are established at an approximate 1-degree spacing, with denser spacing, as required, for areas of crustal motion.

The FBN points are intended to have 95% network accuracies (relative to the National CORS) as follows:

• 1 cm horizontal (total latitude/longitude error; radius of circular error)
• 2 cm ellipsoidal height
• 3 cm orthometric height

The FBN points shall have sufficient stability to insure that the network accuracies are met.

The National Geodetic Survey intends to resurvey the FBN points on a 5-year cycle and assure network maintenance for this monumented component.

For information, contact: NGS Spatial Reference System Division
Attn: Mr. Edward J. McKay
Telephone: 301-713-3191; Fax: 301-713-4324
E-mail
NGS Web site: http://www.ngs.noaa.gov