Precise Ephemeris and Clock Parameters Metadata



Welcome to the Office of Geomatics metadata for the Precise Ephemeris and Precise Clock parameters produced for the Global Positioning System satellites.

This metadata was written using the Content Standards for Digital Geospatial Metadata, June 8, 1994 version, and released by the Federal Geographic Data Committee.

1.0 Identification Information:
basic information about the data set.
2.0 Data Quality Information:
general assessment of the quality of the data set.
4.0 Spatial Reference Information:
description of the reference frame for and the means to encode the coordinates in the data set.
6.0 Distribution Information:
information about the distributor of and options for obtaining the data set
7.0 Metadata Reference Information:
information on the currentness of the metadata information, and the responsible party.

1.0 Identification Information:

1.1 Citation:
1.1.1 Originator: National Geospatial-Intelligence Agency
1.1.2 Publication Date: daily
1.1.4 Title: Global Positioning System Precise Ephemerides and Clock Parameters
1.1.8 Publication Information:
1.1.8.1 Publication Place: Arnold, Missouri
1.1.8.2 Publisher: National Geospatial-Intelligence Agency
1.2 Description:
1.2.1 Abstract: Global Positioning System (GPS) Precise Ephemerides and improved satellite clock parameters are solved for through a post-orbit estimation process. The ephemerides files provide position and velocity vectors for each satellite every 15 minutes. In addition, the satellites' phase and frequency offsets (referenced to GPS time) are also given every 15 minutes. All files are ASCII IGS compliant SP3 format.
1.2.2 Purpose: The precise ephemerides and adjusted clock parameters provide improved accuracy over those given in the GPS satellites' broadcast navigation messages. When used with suitable post processing software these corrections improve the accuracy of GPS derived survey points.
1.3 Time Period of Content:
1.3.1 Range of Dates/Times: Daily from 0000 GPS to 2345 GPS.
1.3.2 Currentness Reference: publication date
1.4 Status:
1.4.1 Progress: Complete
1.4.2 Maintenance and Update Frequency: Daily
1.5 Spatial Domain:
1.5.1 Bounding Coordinates:
1.5.1.1 West Bounding Coordinate: -180.0 degrees
1.5.1.2 East Bounding Coordinate: 180.0 degrees
1.5.1.3 North Bounding Coordinate: 90.0 degrees
1.5.1.4 South Bounding Coordinate: -90.0 degrees
1.6 Keywords:
1.6.1 Theme:
1.6.1.1 Theme Keyword Thesaurus: DoD Glossary of Mapping, Charting, and Geodetic Terms
1.6.1.2 Theme Keyword: Global Positioning System, GPS, precise ephemerides, GPS Clock States
1.7 Access Constraints: All requests for this data must be made to the National Geospatial-Intelligence Agency, which is the sole authorized distributor.
1.8 Use Constraints: None
1.9 Points of Contact:
1.9.2 Contact Organization Primary:
1.9.2.1 Contact Organization: NGA Geospatial Sciences Division
1.9.2.2 Contact Person: Satellite Geophysics Program Manager
1.9.3 Contact Position: Program Manager
1.9.4 Contact Address:
1.9.4.1 Address Type: mailing address
1.9.4.2 Address: 3838 Vogel Road L-41
1.9.4.3 City: Arnold
1.9.4.4 State or Province: Missouri
1.9.4.5 Postal Code: 63010-6238
1.9.4.6 Country: United States of America
1.9.5 Contact Voice Telephone: (314)676-9123 or DSN846-9123
1.9.7 Contact Facsimile Telephone: (314)676-3113 or DSN846-3113
1.9.8 Contact Electronic Mail: gandg@nga.mil
1.9.9 Hours of Service: 0900-1500 Mon to Fri (Central Time)
1.12 Security Information:
1.12.1 Security Classification System: Department of Defense
1.12.2 Security Classification: Restricted
1.12.3 Security Handling Description: Call for more information

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2.0 Data Quality Information:

2.2 Logical Consistency Report: Three day overlapping data sets are used to smooth the data for a single day. The overlaps are compared for repeatability and consistency.
2.3 Completeness Report: Clock and position events are designated in the daily files as appropriate.
2.5 Lineage:
2.5.1 Source Information:
2.5.1.1 Source Citation:
2.5.1.1.1 Originator: National Geospatial-Intelligence Agency and United State Air Force Space Command
2.5.1.1.2 Publication Date: Daily
2.5.1.1.3 Publication Time: 2345 hrs daily
2.5.1.1.4 Title: 15 minute pseudorange data
2.5.1.1.6 Geospatial Data Presentation Form: SP3 ASCII formatted data
2.5.1.1.8 Publication Information:
2.5.1.1.8.1 Publication Place: Arnold, Missouri and Falcon AFB, Colorado
2.5.1.1.8.2 Publisher: NGA and USAF
2.5.1.3 Type of Source Media: online
2.5.1.4 Source Time Period of Content:
2.5.1.4.3 Range of Dates/Times: Daily from 0000 to 2345 hours.
2.5.1.4.4 Source Currentness Reference: Daily
2.5.1.5 Source Citation Abbreviation: NGA data and USAF data
2.5.1.6 Source Contribution: SA corrected pseudorange data is used to define where the GPS satellites were at each 15 minute epoch in relation to the monitor stations active and within view at that time.
2.5.2 Process Step:
2.5.2.1 Process Description: Orbit Mensuration and Navigation Improvement System (OMNIS)
2.5.2.3 Process Date: Periodic with a goal of daily.
2.5.2.6 Process Contact:
2.5.2.6.1 Contact Person Primary
2.5.2.6.1.1 Contact Person: Precise Ephemerides Lead Geodesist
2.5.2.6.1.2 Contact Organization: NGA Geospatial Sciences Division
2.5.2.6.3 Contact Position: Geodesist
2.5.2.6.4 Contact Address:
2.5.2.6.4.1 Address Type: mailing address
2.5.2.6.4.2 Address: 3838 Vogel Road L-41
2.5.2.6.4.3 City: Arnold
2.5.2.6.4.4 State or Province: Missouri
2.5.2.6.4.5 Postal Code: 63010-6238
2.5.2.6.4.6 Country: United States of America
2.5.2.6.5 Contact Voice Telephone: (314) 676-9123 or DSN846-9123
2.5.2.6.7 Contact Facsimile Telephone: (314) 676-3113 or DSN846-3113
2.5.2.6.8 Contact Electronic Mail Address: GPS@nga.mil
2.5.2.6.9 Hours of Service: 0900-1500 Mon to Fri (Central Time)

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4.0 Spatial Reference Information

4.1 Horizontal Coordinate System Definition:
4.1.4 Geodetic Model:
4.1.4.2 Ellipsoid Name: World Geodetic System 1984
4.1.4.3 Semi-major Axis: 6378137
4.1.4.4 Altitude Encoding Method: 298.257223563

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6.0 Distribution Information:

6.1 Distributor:
6.1.1 Contact Person Primary:
6.1.1.1 Contact Person: Archive & Distribution Manager
6.1.1.2 Contact Organization: NGA Geospatial Sciences Division
6.1.3 Contact Position: Geodesist
6.1.4 Contact Address:
6.1.4.1 Address Type: mailing address
6.1.4.2 Address: 3838 Vogel Road L-41
6.1.4.3 City: Arnold
6.1.4.4 State or Province: Missouri
6.1.4.5 Postal Code: 63010-6238
6.1.4.6 Country: United States of America
6.1.5 Contact Voice Telephone: (314) 676-9123 or DSN 846-9123
6.1.7 Contact Facsimile Telephone: (314) 676-3113 or DSN 846-3113
6.1.8 Contact Electronic Mail: GPS@nga.mil
6.1.9 Hours of Service: 0900-1500 Mon to Fri (Central Time)
6.2 Resource Description: Global Positioning System Precise Ephemerides and Clock Parameters
6.4 Standard Order Process:
6.4.1 Non-Digital: N/A
6.4.2 Digital Form:
6.4.2.1 Digital Transfer Information:
6.4.2.1.1 Format Name: ASCII IGS compliant SP3 enhanced format
6.4.2.1.6 File Decompression Technique: Self extracting executable or PKunzip
6.4.2.1.7 Transfer Size: 135 Kbytes for one day of ephemerides (compressed). 900 Kbytes for one week of ephemerides (uncompressed).
6.4.2.2 Digital Transfer Option:
6.4.2.2.1 Online Option:
6.4.2.2.1.1 Computer Contact Information:
6.4.2.2.1.1.1 Network Address:
6.4.2.2.1.1.1.1 Network Resource Name: Self extracting executable files: http://osis.nga.mil/GandG/sathtml/2000peexe.html
6.4.2.2.1.1.1.1 Network Resource Name: Self extracting executable files: http://osis.nga.mil/GandG/sathtml/2000APCexe.html
6.4.2.2.1.2 Access Instructions: Standard Internet Protocols
6.4.2.2.1.3 Online Computer/Operating System: Sun Computers/UNIX
6.4.2.2.2 Offline Option:
6.4.2.2.2.1 Offline Media: 3.5 inch floppy disk
6.4.2.2.2.2 Recording Capacity:
6.4.2.2.2.2.1 Recording Density: 1.44 Megabytes
6.4.2.2.2.3 Recording Format: Self extracting executable or PKUnzip
6.4.2.2.2.4 Compatibility Information: DOS
6.4.3 Fees: None
6.4.4 Ordering Instructions: Call Mr. Dennis Manning, (314) 676-4120, and state the time period required. Data can be mailed on 3.5 disks, e-mailed, or FTPed.
6.4.5 Turnaround: 3 days or less for less than 4 weeks of data. Larger orders may take longer.
6.6 Technical Prerequisites: A DOS platform or the ability to convert compressed files to the user's platform requirements is needed.
6.7 Available Time period:
6.7.3 Range of Dates/Times:
6.7.3.1 Beginning Date: January 1986 (GPS week 312)
6.7.3.3 Ending Date: Present

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7.0 Metadata Reference Information:

7.1 Metadata Date: 1 December 1995
7.2 Metadata Review Date: 1 March 1998
7.3 Metadata Future Review Date: 1 March 1999
7.4 Metadata Contact:
7.4.1 Contact Person Primary:
7.4.1.1 Contact Person: Archive & Distribution Manager
7.4.1.2 Contact Organization: NGA Geospatial Sciences Division
7.4.2 Contact Organization Primary:
7.4.2.1 Contact Organization: NGA Geospatial Sciences Division
7.4.2.2 Contact Person:
7.4.3 Contact Position:
7.4.4 Contact Address:
7.4.4.1 Address Type: mailing address
7.4.4.2 Address: 3838 Vogel Road L-41
7.4.4.3 City: Arnold
7.4.4.4 State or Province: Missouri
7.4.4.5 Postal Code: 63010-6238
7.4.4.6 Country: United States of America
7.4.5 Contact Voice Telephone: (314)676-9123 or DSN846-9123
7.4.7 Contact Facsimile Telephone: (314)676-3113 or DSN846-3113
7.4.8 Contact Electronic Mail: GPS@nga.mil
7.4.9 Hours of Service: 0900-1500 Mon to Fri (Central Time)
7.5 Metadata Standard Name: FGDC Content Standards for Digital Geospatial Metadata
7.6 Metadata Standard Version: June 8, 1994

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Point of Contact: Office of Geomatics / GPS Division
phone (314) 676-9123, DSN 846-9123
gandg@nga.mil

Document last modified April 29, 2013