Orbit Data and Resources on Active GNSS Satellites
Click to download the GPS World Almanac (PDF, Dcember 2012 issue).
GPS Constellation
General Notes:
1. “SV Number” refers to space vehicle number. “PRN Number” refers to the satellite’s unique pseudorandom noise code.
2. Clock: Rb = rubidium; Cs = cesium.
3. “Launched” and “Usable” dates are based on Universal Time.
4. The current GPS constellation consists of 9 usable Block IIA satellites, 12 Block IIRs, 7 Block IIR-Ms, and 3 Block IIF for a total of 31 satellites and is under FOC (Full Operational Capability). The constellation is in the 24+3 (or “Expandable 24”) configuration with satellites occupying the fore and aft bifuracted slots in the B, D, and F planes. There are currently four reserve satellites, SVNs 27, 32, 37, and 49 near slots A1, F1, C1, and B1-F, respectively. SVN49 resumed transmitting signals, this time as PRN27, on October 18, 2012, but is not set healthy and not included in broadcast almanacs.
5. SVN35 and 36 carry onboard corner-cube reflectors for satellite laser ranging (SLR). SLR tracking of the satellites permits analysts to differentiate between onboard clock errors and satellite ephemeris errors in GPS tracking.
6. Selective availability (SA) was set to zero on all satellites by presidential order on May 2, 2000 at approximately 4:00 UT. Previous Almanacs provide a history of SA status.
7. Antispoofing (AS) was activated on January 31, 1994, on all Block IIs. AS is occasionally off for testing and other purposes. Previous Almanacs provide a history of AS status.
8. The design life and mean-mission duration goals of the Block IIA, IIR, and IIF satellites are 7.5 and 6 years, 10 and 7.5 years, and 12 and 9.9 years, respectively.
9. GPS World believes this information to be correct as of press time. However, because of the satellite constellation’s evolving nature, readers should contact GPS information services listed on these pages for more current data.
10. Dr. Richard Langley of the University of New Brunswick provided the GPS satellite status information and compiled the notes.
Performance Notes:
A. SVN27/PRN27 decommissioned from active service on October 6, 2012.
B. SVN65/PRN24 launched on October 4, 2012, at 12:10 UTC and set usable on November 14, 2012, at 00:33 UTC. Currently sited near SVN39/PRN09 at slot A1.
GPS Satellite & System Information
International GNSS Service
National Executive Committee for Space-Based Positioning, Navigation & Timing
2nd Space Operations Squadron
U.S. Coast Guard Navigation Center
GLONASS Constellation
General Notes:
1. The first GLONASS satellite was launched October 12, 1982.
2. The GLONASS numbering scheme used in this table includes the eight “dummy” satellites orbited as ballast along with “real” satellites on the first seven GLONASS launches. The second number (in parentheses) in the “GLONASS Number” column is that assigned by the Russian Space Forces.
3. The Russian Federation designated the “Kosmos Number.”
4. GLONASS numbers 1–94 have been withdrawn from service.
5. All operational satellites are GLONASS-M satellites, except GLONASS 125, which is a GLONASS-K1 satellite.
6. All launch and usable dates are based on Moscow Time (Universal Time + 3 hours).
7. Almanac/slot numbers in parentheses indicate the physical orbital slot of reserve/test satellites or those in maintenance and not in the almanac.
8. Channel number “k” indicates L1 and L2
carrier frequencies: L1 = 1,602 + 0.5625 k (MHz); L2 = 1,246 + 0.4375 k (MHz).
9. All GLONASS satellites use cesium atomic clocks.
10. Twenty-four GLONASS satellites are set healthy.
11. The latest GLONASS launch (of a single satellite) was on November 28, 2011. The next launch is scheduled for December 2012.
12. New GLONASS channel allocations were introduced September 1993 to reduce interference to radio astronomy. Note the use of the same channel on pairs of antipodal satellites.
13. GPS World believes this information to be correct as of press time. However, because of the satellite constellation’s evolving nature, we encourage readers to contact the GLONASS sources listed on these pages for more current information.
14. Information compiled by Richard Langley.
Performance Notes:
A. GLONASS 95 was switched from a reserve to an active satellite on October 23, 2012.
B. GLONASS 100 is a reserve satellite.
C. GLONASS 108 is a reserve satellite.
D. GLONASS 112 remains in maintenance mode.
E. GLONASS 113 remains in maintenance mode.
F. GLONASS 115 was switched to maintenance mode on September 9, 2012.
G. GLONASS 125 ceased transmissions on its assigned channel on November 30, 2011 and was removed from the almanac. It was reactivated by early April 2012 but does not appear in the almanac. It identifies itself as satellite 26 in its broadcast ephemeris.
H. GLONASS 127 was set healthy between September 20, 2012, and October 18, 2012, using almanac slot 8. Now a reserve satellite.
GLONASS System Information
The Information–Analytical Center (IAC) of the Russian Space Agency publishes official information about GLONASS status and plans as well as consultation, information, and scientific-method services to increase GLONASS applications efficiency. E-mail glonass-ianc@mcc.rsa.ru.
Galileo Constellation
Notes:
A. Navigation signals from GIOVE-A were switched off on June 30, 2012, and the satellite decommissioned for ESA use.
B. Navigation signals from GIOVE-B were switched off on July 23, 2012, and the satellite decommissioned for ESA use.
C. ProtoFlight Model uses PRN code 11. Switched from hydrogen maser to rubidium atomic clock on November 1, 2012.
D. Flight Model 2 uses PRN code 12. Switched from rubidium atomic clock to hydrogen maser on July 23, 2012.
E. Designated orbits achieved. Initial transmissions expected in late 2012.
Galileo System Information
Galileo is a joint initiative of the European Commission (EC) and the European Space Agency (ESA). Initially, they formed the Galileo Joint Undertaking (GJU) to manage Galileo’s development phase. The European GNSS Supervisory Authority (GSA), headquartered in Brussels, Belgium, took over Galileo responsibility from GJU on January 1, 2007. The GSA’s tasks include management of the first series of satellites to ensure the large-scale demonstration of the capabilities and reliability of the Galileo system. The first two Galileo satellites will secure the system’s frequency allocation and validate key technologies for the full Galileo constellation. Surrey Satellite Technology Ltd. (SSTL) in Guildford, United Kingdom, constructed the first test satellite. Formerly known as the Galileo System Test Bed (GSTB) V2/A satellite, it has been christened Galileo In-Orbit Validation Element-A (GIOVE-A) and was launched on December 28, 2005. The second test satellite, GSTB V2/B or GIOVE-B, constructed by a team led by Astrium GmbH in Ottobrunn near Munich, Germany, was launched on April 26, 2008. It continues to transmit test signals. The first two in-orbit validation (IOV) satellites, provided by Astrium, were launched on October 21, 2011, and are transmitting test signals. The next two IOV satellites are scheduled for launch during the fall of 2012.
Beidou/Compass Constellation
Notes:
A. GEO, formerly at 58.75°E, placed in disposal orbit on or about November 21, 2011.
B. GEO, formerly at 80.5°E, placed in disposal orbit on or about November 23, 2011.
C. GEO, formerly at 110.5°E, shifted to 85°E between about June 2 and July 7, 2012.
D. GEO, formerly at 145°E, placed in disposal orbit on or about February 18, 2009.
E. Flight-test satellite.
F. Initially achieved geostationary orbit at a longitude of about 84.5°E, but appears to have become uncontrollable shortly thereafter. Librating about the 75°E libration point.
G. GEO, formerly at 144.5°E, shifted to 140°E between about June 30 and July 9, 2011.
H. It appears that the obit of G3 is being shifted. The sub-satellite longitude is currently about 97°E.
Beidou/Compass System Information
China fielded a demonstration regional satellite-based navigation system known as Beidou (Chinese for the “Big Dipper” asterism) following a program of research and development that began in 1980. The initial constellation of three geostationary Earth orbit (GEO) satellites was completed in 2003. A fourth GEO satellite was launched in 2007. The initial regional Beidou system (Beidou-1) is being expanded, in stages, into a global system known as Beidou-2 or Compass. It will include five GEO satellites, 27 medium Earth orbit (MEO) satellites, and five inclined geosynchronous orbit (IGSO) satellites. The system will cover the Asia-Pacific region by 2012 with the global system expected to be fully completed by 2020. Beidou-2/Compass was declared operational for use in China and surrounding areas on December 27, 2011.
For more information:
www.dragoninspace.com/navigation/beidou.aspx
www.dragoninspace.com/navigation/compass-beidou2.aspx
www.beidou.gov.cn
Satellite-Based Augmentation Systems
Notes:
A. Inmarsat 3-F2 began Safety-of-Life Service on March 2, 2011, and is transmitting message type 2.
B. Artemis switched roles with Inmarsat-4-F2 on March 22/23, 2012. Now transmitting message type 0/0 for industry tests.
C. Inmarsat-4-F2 began Safety-of-Life Service on March 22, 2012, and is transmitting message type 2.
D. SES-5 (also known as Sirius 5 and Astra 4B) was launched on July 9, 2012. Not yet active.
E. GSAT-8 was launched on May 20, 2011. Satellite is transmitting test signals.
F. GSAT-10 was launched on September 28, 2012. Satellite is transmitting test signals.
G. MSAS commissioned for aviation use on September 27, 2007. Either satellite can transmit both PRN signals if necessary.
H. QZS-1 (nicknamed Michibiki) transmits an L1 augmentation signal using PRN code 183. That signal is in test mode.
I. Luch-5A was launched on December 11, 2011. Initially positioned at 58.5° E, it was shifted to 95° E between about May 30 and June 28, 2012. Transmissions as PRN 140 began on July 12, 2012. Currently transmitting occasional, non-coherent code/carrier test signals.
J. Luch-5B was launched on November 2, 2012. Expected to be positioned at 16° W and use PRN code 125. Not yet active.
K. Galaxy 15 ranging supports enroute through precision approach modes. Switched to backup satellite oscillator on January 6, 2012.
L. Anik F1R ranging supports enroute through precision approach modes.
M. The Galaxy 15 and and Anik F1R payloads, operated by Lockhhed Martin for the FAA, are known as LMPRS-1 and LMPRS-2, respectively.
N. Inmarsat-4-F3 supports non-precision approach ranging service.
GNSS Internet Resources
United States and Canada
Canadian Space Geodesy Forum
This University of New Brunswick service presents daily GPS constellation status reports, ionospheric disturbance warnings, and news and discussion about GPS and other space-based positioning systems by way of electronic mail. Downloadable files are also available. To subscribe, e-mail the one-line message [sub CANSPACE your_name] to listserv@UNB.CA.
For more information: Terry Arsenault or Richard Langley, phone (506) 453-4698, fax (506) 453-4943, e-mail se@unb.ca.
National Executive Committee (EXCOM) for Space-Based Positioning, Navigation & Timing (PNT)
The EXCOM advises senior national government leadership and coordinates with federal agencies about policy matters concerning GPS, its augmentations, and related systems. The deputy secretaries of Defense and Transportation jointly chair the EXCOM. Executive Committee membership includes equivalent-level officials from NASA, the departments of State, Commerce, Homeland Security, Agriculture, Interior, and the Joint Chiefs of Staff. Components of the Executive Office of the President and other selected agencies participate as observers. The National Coordination Office, an interagency staff directed by a member of the Senior Executive Service in Washington, provides day-to-day administrative and operational support to the EXCOM. The National Space-Based PNT Advisory Board operates in an independent advisory capacity for the EXCOM as directed by the National PNT Policy and in accordance with the Federal Advisory Committee Act.
For information contact: National Coordination Office for Space-Based PNT, Herbert C. Hoover Building, Rm. 2518, 1401 Constitution Ave. NW, Washington, D.C. 20230, phone: 202-482-5809, fax: 202-482-4429, e-mail: pnt.office@pnt.gov.
National Geospatial-Intelligence Agency (NGA)
Precise GPS Orbit Information and Earth Orientation Parameter Predictions (EOPP)
Anonymous FTP Access:
ftp://ftp.nga.mil/pub2/gps/pedata/
ftp://ftp.nga.mil/pub2/gps/apcpe/
ftp://ftp.nga.mil/pub2/gps/predictions/9DayGPSpreds/
ftp://ftp.nga.mil/pub2/gps/predictions/Rapids/
The NGA Global Positioning System Division/Ephemeris Support and Analysis Team maintains a World Wide Web page for Department of Defense and civilian users with precise GPS orbit and clock information based on tracking data collected from NGA, U.S. Air Force, and IGS stations. Daily and weekly precise ephemeris and clock estimate data, both center-of-mass (pedata) and antenna phase center (apcpe) are calculated on a 15-minute interval. Approximately two years of data are kept at this site with previous data available on request. NGA also offers a nine-day orbit prediction ephemeris along with a daily orbit and clock “rapid” ephemeris, also calculated on a 15-minute interval. Earth Orientation Parameter Predictions, based on data provided by the U.S. Naval Observatory, are provided. EOP coefficients and predictions, used by the Air Force GPS Operational Control Segment, are calculated each Thursday to go into effect the following Sunday through Saturday (each new GPS week). Daily EOPs are computed for testing and evaluation to be used in GPS III.
For more information: Duty hours (6 a.m.–6 p.m., Mon–Fri): 314-676-9142 or DSN 846-9142, e-mail: gps@nga.mil.
24-hour contact: 314-676-9140 or DSN 846-9140.
Natural Resources Canada, Canadian Spatial Reference System
Natural Resources Canada, Geodetic Survey Division, operates the Canadian Active Control System (CACS), a national network of continuously operating GPS tracking stations. Products derived from CACS include GPS observation data, precise GPS orbits, and precise GPS clock corrections. The system supports the positioning requirements of a broad range of users, including the most demanding post-mission scientific applications, providing coordinates in either the Canadian Spatial Reference System (CSRS) or the International Terrestrial Reference Frame (ITRF). An online Precise Point Positioning (CSRS-PPP) service allows GPS users from around the world to recover accurate positions from a single GPS receiver by submitting their RINEX observation data via the Internet. Information about access to CACS, data availability, and other geodetic products is available 24 hours a day from a free online subscription service (CSRS Online Database).
For more information: Contact our Information Management and Client Services unit, 615 Booth Street, Ottawa, Ontario, Canada K1A 0E9; phone (613) 995-4410; fax (613) 995-3215; e-mail information@geod.nrcan.gc.ca.
U.S. Coast Guard Navigation Center
This site offers GPS constellation status, scheduled outage updates, user advisories, and almanac data as well as Differential GPS and Coast Guard Local Notice to Mariners information.
Voice recording for GPS constellation status: (703) 313-5907.
For more information: Contact the NIS Watchstander, 24 hours a day, at phone (703) 313-5900, fax (703) 313-5920, or e-mail tis-pf-nisws@uscg.mil.
Scripps Orbit and Permanent Array Center (SOPAC)
GPS Orbits, Coordinate Information, and Data Archive
California Spatial Reference Center
CRTN: California Real Time Network
The Scripps Institution of Oceanography, University of California, San Diego, maintains SOPAC, which provides precise, rapid, ultra-rapid, and hourly orbits for the International GNSS Service (IGS) and NOAA’s Global Systems Division (GSD). Many GPS-related services and tools are available from SOPAC’s website such as SCOUT (a global ITRF Coordi-nates Generator), Site Information Manager (SIM), On-line Map Interface (SOMI) and GPS Explorer. SOPAC archives 24-hour RINEX data from about 1,500 continuous GPS sites from more than 20 scientific networks around the world, with a concentration in western North America. SOPAC also maintains the operational center for the California Spatial Reference Center, or CSRC. The CSRC provides California’s geodetic framework for scientific, engineering, and geographical information systems in partnership with the National Geodetic Survey. SOPAC also collects and archives high-rate (1 Hz), low latency (1 second) GPS data from stations in California. For information about access to real-time data streams, visit http://sopac.ucsd.edu/projects/realtime/.
For more information: Contact SOPAC, Scripps Institution of Oceanography, UCSD, IGPP 0225, 9500 Gilman Drive, La Jolla, CA 92093-0225, USA; call (858) 822-2156, fax (858) 534-9873, or e-mail archive@gpsmail.ucsd.edu or Director Yehuda Bock, ybock@ucsd.edu.
DoD GPS Operations Center and 2SOPS Constellation Status
The U.S. Department of Defense (DoD) GPS Operations Center and the 2nd Space Operations Squadron (2SOPS), U.S. Air Force, maintain Internet sites for military and DoD users only; civilians are referred to the U.S. Coast Guard’s Navigation Information Service (see above). The GPS Operations Center provides DOP predictions, GPS performance assessments, anomaly impact analysis, GPS FAQs, and other services to meet the needs of GPS users in the field. 2SOPS operates a GPS Constellation Status site with scheduled outages, user advisories, almanac data, electronic mail, and downloadable files.
For more information: Questions and anomaly reports from civilians and industry, contact Navigation Information Service (see previous listing). DOD-associated activities only, e-mail gps_support@schriever.af.mil.
GPS Test Center of Expertise
The 746 Test Squadron, based at Holloman Air Force Base in New Mexico, provides archived almanac data in SEM3.6 and YUMA formats and a special almanac detailing the short GPS week, observed range errors as viewed from the GPS Satellite Reference Station at Holloman Air Force Base, constellation status, and user advisories. Information dates back to 1992 and is available 24 hours a day. The site also will soon offer links to the GPS Test Center of Expertise legacy databases.
For more information: Michael P. Brown, phone (575) 679-2863, e-mail michael.brown@Holloman.af.mil.
U.S. National Geodetic Survey (NGS) GPS Orbit Information
NOAA’s National Geodetic Survey (NGS) manages a network of Continuously Operating Reference Stations (CORS) that provide GPS data to support three-dimensional positioning, meteorology, space weather, and geophysical applications throughout the United States, its territories, and a few foreign countries. The CORS network is a multi-purpose cooperative endeavor involving more than 200 government, academic. and private organizations. NGS partners contribute more than 1,900 independently owned and operated stations to the CORS network. The primary objective of the CORS Program is to define and maintain the National Spatial Reference System (NSRS). The CORS Program also:
- Provides free access to GPS data from the CORS network sites.
- Establishes coordinates and velocities of CORS stations with respect to the NSRS.
- Enables users to determine centimeter-level positions with respect to the NSRS by simultaneously processing their own GNSS data with data from the CORS network.
- Computes GPS satellite orbits to support post-processing applications.
- Provides web services for post-processing GPS data via its Online Positioning User Service (OPUS).
- Calibrates GPS antenna phase center values.
- Establishes guidelines for operating and using active geodetic control networks.
NGS continually updates its website with new information on the CORS program.
For more information: e-mail ngs.cors@noaa.gov
U.S. Naval Observatory
The U.S. Naval Observatory (USNO) provides GPS timing data and status information.
For more information: Contact Stephen Mitchell, phone: 202-762-0740 or DSN 762-0740, e-mail: stephen.mitchell@usno.navy.mil.
International
International GNSS Service (IGS)
IGS Data Centers
ftp://igscb.jpl.nasa.gov
The foundation of IGS is a global network of more than 350 permanent, continuously operating, geodetic-quality GPS and GPS/GLONASS sites. The station data are archived at four global data centers and six regional data centers. Ten analysis centers regularly process the data and contribute products to the analysis center coordinator, who produces the official IGS combined orbit and clock products. Timescale, ionospheric, and tropospheric products are analogously formed by specialized coordinators for each. The IGS reference-frame coordinator determines tracking site coordinates and velocities from analysis centers’ solutions, and organizes the IGS contribution to the International Terrestrial Reference Frame (ITRF). The IGS Central Bureau is responsible for day-to-day management of the IGS, following policies set by the IGS International Governing Board as well as for communication and outreach. More than 200 institutions and organizations in more than 90 countries contribute to the IGS, a service established within the International Association of Geodesy since 1994. The IGS intends to integrate future GNSS signals, such as Galileo, into its activities, as demonstrated by the successful incorporation of GLONASS.
For more information: Contact International GNSS Service Central Bureau, Jet Propulsion Lab MS 238-540, Pasadena, CA 91109 USA; phone (818) 354-2077, fax (818) 393-6686, email cb@igs.org.
Australia
Geoscience Australia is Australia’s national agency for geoscience research and geospatial information. It maintains a comprehensive Web site with information about many GPS-related topics. Users can download data from the Australian Regional GPS Network and view graphs of data quality and time-series of positions. An online GPS processing service (AUSPOS) allows users to upload dual-frequency Rinex data and receive computed ITRF positions rapidly by e-mail. Within Australia, these ITRF positions are also transformed to the Geocentric Datum of Australia. The site provides information about Australian coordinates, datums, and transformations. Geoid-ellipsoid separations for the region can be downloaded or computed on line.
For more information: Contact Geoscience Australia, phone +61 (2) 6249 9111, fax +61 (2) 6249 9929, e-mail geodesy@ga.gov.au.
Czech Republic
ftp://merope.feld.cvut.cz/pub/almanac/
The Czech Technical University, Faculty of Electrical Engineering, Department of Radio Engineering in Prague, Czech Republic, offers historical constellation status and almanac data for both GPS and GLONASS systems.
For more information: E-mail service administrator at pavel.puricer@fel.cvut.cz or contact Frantisek Vejrazka, Czech Technical University, Technicka 2, 166 27 Prague 6, Czech Republic; phone: (+420) 2 2435 2246, fax: (+420) 2 3333 9801, e-mail: vejrazka@feld.cvut.cz.
Denmark
Kort og Matrikelstyrelsen (National Survey and Cadastre-Denmark) provides GPS raw carrier-phase data by request and maintains the following services: NAV-DK and Code |corrections distributed by way of cellular telephony. These services are based on the permanent reference station network for GPS operated by the National Survey and Cadastre-Denmark.
For more information: Contact Casper Jepsen or Bo Hansen, Kort and Matrikelstyrelsen, Rentemestervej 8, DK-2400 Copenhagen NV, Denmark; phone +45 72 54 50 00, fax +45 35 87 50 51, e-mail kms@kms.dk.
Russia
The Information–Analytical Center (IAC) of the Russian Space Agency publishes official information about GLONASS status and plans as well as consultation, information, and scientific-method services to increase GLONASS applications efficiency. It provides current constellations, Earth maps of the current and daily navigation availabilities, results of GNSS navigation field monitoring in the Moscow area in a real-time mode, and other data.
For more information: IAC, Mission Control Center, e-mail glonass-ianc@mcc.rsa.ru.