WELCOME

Welcome to the National Geospatial-Intelligence Agency (NGA) Global Positioning System (GPS) Division Home Page. This web site allows one access to the NGA GPS Precise Ephemeris (PE) and Earth Orientation Parameter Prediction (EOPP) data files. The NGA GPS PE data files conform to the industry standard SP3 enhanced format. (Please note Documentation Page to the left on the main page, if necessary.) Two different GPS PE data types are stored at this web site: a Satellite Center of Mass (EPH) and a Satellite Antenna Phase Center (APC). Both ephemeris data formats are stored as self-extracting (.exe) executables. These data, along with current and past EOPP values, can be downloaded from either the FTP sites listed or from the calendar table format also listed to the left on the main page. A DOS PKZIP format, and earlier generated PE and EOPP data, are available, and can be obtained by contacting the NGA GPS Division office.

A third GPS ephemeris data type, Satellite Antenna Phase Center (ANT) with an alternate satellite clock solution, is now stored at this web site. This ephemeris is intended to be used with the Geodetic Absolute Sequential Positioning (GASP) program. The GASP program is currently only available (via NGA) to approved users. The ANT formatted data can be downloaded from the FTP site listed on the main page, to the left.

Also note, our main page has other items of interest, to include our documentation page which contains information about the ephemeris, stations, antenna offsets, and Earth Orientation and SP3 format documentation. The GPS satellite information Summary and Supplement page contains up-to-date information on the individual satellites for all who have an interest in GPS.

Our main page also has direct links to other areas of the GEOINT Sciences Office at NGA. We also have the latest (and updated) links to other related areas of GPS studies and interests.

We welcome all comments, questions, and GPS satellite data requests.E-mail to the NGA GPS Division office or phone (314)676-9142 or DSN 846-9142.

Document last modified Wednesday, 09-Jul-2008 14:37:43 EDT