Navigation Center
United States Coast Guard
U.S. Department of Homeland Security

GPS Constellation

The Global Positioning System Directorate has approved a change to the Navstar GPS Control Segment to User Support Community Interfaces (ICD-GPS-240 and ICD-GPS-870) which will remove GPS satellite plane/slot and clock information from the Operational Advisory message. This change proposal was approved by the GPS Interface Control Working Group in December of 2018. SVN/PRN, Block Type, and NANU details will continue to be included.

A depiction of the GPS constellation of satellites with slot and plane designations is provided here as an easy-to-read graphic which will be updated as satellites enter or leave the constellation. During the GPS modernization process, the orbital configuration, as indicated by the constellation slant chart, and control station configuration may not match over the long term. For modelling purposes, the slant chart indicates actual orbital slot and plane assignments. It should be noted that the graphic merely identifies orbital slot and plane assignments and does not reflect the operational status of GPS satellites. The operational status of the GPS constellation is detailed below.

Expandable Slot Designations
B D F
B5=B1F D5=D2F F5=F2F
B1=B1A D2=D2A F2=F2A
GPS CONSTELLATION STATUS FOR
Plane Slot Sort descending SVN PRN Block-Type Clock Outage Start NANU Type NANU Subject
B 1 56 16 IIR RB 31 MAY 2024 FCSTDV SVN56 (PRN16) FORECAST OUTAGE JDAY 152/0530 - JDAY 152/1730 1
C 1 57 29 IIR-M RB 20 MAR 2024 FCSTSUMM SVN57 (PRN29) FORECAST OUTAGE SUMMARY JDAY 080/1936 - JDAY 080/2045 0
D 1 61 2 IIR RB 09 FEB 2024 FCSTSUMM SVN61 (PRN02) FORECAST OUTAGE SUMMARY JDAY 040/0231 - JDAY 040/0833 0
A 1 65 24 IIF RB 11 JAN 2024 FCSTSUMM SVN65 (PRN24) FORECAST OUTAGE SUMMARY JDAY 011/1148 - JDAY 011/1637 0
E 1 69 3 IIF RB 05 JAN 2024 FCSTSUMM SVN69 (PRN03) FORECAST OUTAGE SUMMARY JDAY 005/0748 - JDAY 005/1231 0
F 1 70 32 IIF RB 25 AUG 2023 FCSTSUMM SVN70 (PRN32) FORECAST OUTAGE SUMMARY JDAY 237/0234 - JDAY 237/0740 0
A 2 52 31 IIR-M RB 02 JUN 2023 FCSTSUMM SVN52 (PRN31) FORECAST OUTAGE SUMMARY JDAY 153/1332 - JDAY 153/2024 0
F 2 55 15 IIR-M RB 02 NOV 2023 FCSTSUMM SVN55 (PRN15) FORECAST OUTAGE SUMMARY JDAY 306/2124 - JDAY 307/0316 0
B 2 62 25 IIF RB 22 MAY 2024 FCSTSUMM SVN62 (PRN25) FORECAST OUTAGE SUMMARY JDAY 143/0850 - JDAY 143/1406 1
C 2 66 27 IIF RB 30 DEC 2023 UNUSABLE SVN66 (PRN27) UNUSABLE JDAY 364/1107 - JDAY 033/1852 0
E 2 73 10 IIF CS 09 FEB 2024 FCSTSUMM SVN73 (PRN10) FORECAST OUTAGE SUMMARY JDAY 040/1642 - JDAY 047/0821 0
B 3 44 22 IIR RB 19 OCT 2023 FCSTSUMM SVN44 (PRN22) FORECAST OUTAGE SUMMARY JDAY 292/1559 - JDAY 292/2125 0
D 3 45 21 IIR RB 13 OCT 2023 FCSTSUMM SVN45 (PRN21) FORECAST OUTAGE SUMMARY JDAY 286/0646 - JDAY 286/1147 0
E 3 50 5 IIR-M RB 26 JAN 2024 FCSTSUMM SVN50 (PRN05) FORECAST OUTAGE SUMMARY JDAY 026/0218 - JDAY 026/0737 0
A 3 64 30 IIF RB 14 JUL 2023 FCSTSUMM SVN64 (PRN30) FORECAST OUTAGE SUMMARY JDAY 195/0148 - JDAY 195/0659 0
F 3 68 9 IIF RB 14 SEP 2023 FCSTSUMM SVN68 (PRN09) FORECAST OUTAGE SUMMARY JDAY 257/2352 - JDAY 258/0504 0
C 3 72 8 IIF CS 21 FEB 2024 FCSTSUMM SVN72 (PRN08) FORECAST OUTAGE SUMMARY JDAY 052/2059 - JDAY 058/2211 0
A 4 48 7 IIR-M RB 25 MAY 2024 UNUSUFN SVN48 (PRN07) UNUSABLE JDAY 146/1620 - UNTIL FURTHER NOTICE 1
E 4 51 20 IIR RB 18 MAY 2023 FCSTSUMM SVN51 (PRN20) FORECAST OUTAGE SUMMARY JDAY 138/2243 - JDAY 139/0444 0
C 4 53 17 IIR-M RB 17 MAY 2024 UNUSABLE SVN53 (PRN17) UNUSABLE JDAY 138/0116 - JDAY 138/2008 0
B 4 58 12 IIR-M RB 01 SEP 2023 FCSTSUMM SVN58 (PRN12) FORECAST OUTAGE SUMMARY JDAY 244/0137 - JDAY 244/0726 0
D 4 67 6 IIF RB 21 DEC 2023 FCSTSUMM SVN67 (PRN06) FORECAST OUTAGE SUMMARY JDAY 355/1123 - JDAY 355/1629 0
F 4 74 4 III RB 08 MAR 2024 FCSTSUMM SVN74 (PRN04) FORECAST OUTAGE SUMMARY JDAY 068/0750 - JDAY 068/1348 0
C 5 59 19 IIR RB 20 DEC 2022 FCSTSUMM SVN59 (PRN19) FORECAST OUTAGE SUMMARY JDAY 354/1744 - JDAY 354/2305 0
B 5 71 26 IIF RB 14 DEC 2023 FCSTSUMM SVN71 (PRN26) FORECAST OUTAGE SUMMARY JDAY 348/1723 - JDAY 348/2154 0
E 5 76 23 III RB 13 DEC 2022 FCSTSUMM SVN76 (PRN23) FORECAST OUTAGE SUMMARY JDAY 347/1100 - JDAY 347/2350 0
D 5 78 11 III RB 30 JUN 2023 FCSTSUMM SVN78 (PRN11) FORECAST OUTAGE SUMMARY JDAY 181/0528 - JDAY 181/1134 0
F 6 43 13 IIR RB
D 6 75 18 III RB 19 MAY 2022 FCSTSUMM SVN75 (PRN18) FORECAST OUTAGE SUMMARY JDAY 139/2019 - JDAY 140/0203 0
B 6 77 14 III RB 28 MAR 2022 UNUSABLE SVN77 (PRN14) UNUSABLE JDAY 087/0740 - JDAY 087/2035 0
A 6 79 28 III RB 30 NOV 2023 FCSTSUMM SVN79 (PRN28) FORECAST OUTAGE SUMMARY JDAY 334/1319 - JDAY 334/1947 0

General Information NANUs
2020089 NOTICE ADVISORY TO NAVSTAR USERS (NANU) 2020089 NANU TYPE: GENERAL
*** GENERAL MESSAGE TO ALL GPS USERS ***
Please disregard NANU 2020088 due to an error in the naming convention. Outage start and stop times remain accurate. The correct NANU will be labeled UNUSABLE.
*** GENERAL MESSAGE TO ALL GPS USERS ***

POC: CIVILIAN - NAVCEN AT 703-313-5900, HTTPS://WWW.NAVCEN.USCG.GOV
MILITARY - GPS OPERATIONS CENTER at HTTPS://GPS.AFSPC.AF.MIL/GPSOC, DSN 560-2541,
COMM 719-567-2541, gpsoperationscenter@us.af.mil, HTTPS://GPS.AFSPC.AF.MIL
MILITARY ALTERNATE - JOINT SPACE OPERATIONS CENTER, DSN 276-3526. COMM 805-606-3526.
JSPOCCOMBATOPS@US.AF.MIL
2022002 NOTICE ADVISORY TO NAVSTAR USERS (NANU) 2022002 NANU TYPE: GENERAL
*** GENERAL MESSAGE TO ALL GPS USERS ***
On approximately 20 JAN 2022, SVN41 will resume transmitting L-band utilizing PRN22.

On 20 JAN 2022, after 2200Z, GPS will transition SVN41 (PRN22) into the broadcast almanac for all satellites:
- The almanac transition, accomplished one satellite at a time, will require approximately 24 hours to complete
- Before, during, and after transition SVN41 (PRN22) will remain unusable until further notice
- Future NANUs will notify users of any changes to the above stated status
*** GENERAL MESSAGE TO ALL GPS USERS ***

POC: CIVILIAN - NAVCEN AT 703-313-5900, HTTPS://WWW.NAVCEN.USCG.GOV
MILITARY - GPS OPERATIONS CENTER at HTTPS://GPS.AFSPC.AF.MIL/GPSOC, DSN 560-2541,
COMM 719-567-2541, gpsoperationscenter@us.af.mil, HTTPS://GPS.AFSPC.AF.MIL
MILITARY ALTERNATE - JOINT SPACE OPERATIONS CENTER, DSN 276-3526. COMM 805-606-3526.
JSPOCCOMBATOPS@US.AF.MIL
2022016 NOTICE ADVISORY TO NAVSTAR USERS (NANU) 2022016 NANU TYPE: GENERAL
*** GENERAL MESSAGE TO ALL GPS USERS ***
PLEASE DISREGARD NANU 2022015 DUE TO AN ERROR IN THE NAMING CONVENTION. OUTAGE START AND STOP TIMES REMAIN ACCURATE. THE CORRECT NANU WILL BE LABELED UNUSABLE.
*** GENERAL MESSAGE TO ALL GPS USERS ***

POC: CIVILIAN - NAVCEN AT 703-313-5900, HTTPS://WWW.NAVCEN.USCG.GOV
MILITARY - GPS OPERATIONS CENTER at HTTPS://GPS.AFSPC.AF.MIL/GPSOC, DSN 560-2541,
COMM 719-567-2541, gpsoperationscenter@us.af.mil, HTTPS://GPS.AFSPC.AF.MIL
MILITARY ALTERNATE - JOINT SPACE OPERATIONS CENTER, DSN 276-3526. COMM 805-606-3526.
JSPOCCOMBATOPS@US.AF.MIL
2022042 NOTICE ADVISORY TO NAVSTAR USERS (NANU) 2022042 NANU TYPE: GENERAL
*** GENERAL MESSAGE TO ALL GPS USERS ***
NANU 2022040 Labelled Incorrectly. NANU 2022041 Reflects Correct Label.
*** GENERAL MESSAGE TO ALL GPS USERS ***

POC: CIVILIAN - NAVCEN AT 703-313-5900, HTTPS://WWW.NAVCEN.USCG.GOV
MILITARY - GPS OPERATIONS CENTER at HTTPS://GPS.AFSPC.AF.MIL/GPSOC, DSN 560-2541,
COMM 719-567-2541, gpsoperationscenter@us.af.mil, HTTPS://GPS.AFSPC.AF.MIL
MILITARY ALTERNATE - JOINT SPACE OPERATIONS CENTER, DSN 276-3526. COMM 805-606-3526.
JSPOCCOMBATOPS@US.AF.MIL
2022054 NOTICE ADVISORY TO NAVSTAR USERS (NANU) 2022054 NANU TYPE: GENERAL
*** GENERAL MESSAGE TO ALL GPS USERS ***
NANU 2022053 Outage Stop Time Incorrect, Outage Ongoing. UNUSABLE to Follow. NANU 2022053 is to be Disregarded.
*** GENERAL MESSAGE TO ALL GPS USERS ***

POC: CIVILIAN - NAVCEN AT 703-313-5900, HTTPS://WWW.NAVCEN.USCG.GOV
MILITARY - GPS OPERATIONS CENTER at HTTPS://GPS.AFSPC.AF.MIL/GPSOC, DSN 560-2541,
COMM 719-567-2541, gpsoperationscenter@us.af.mil, HTTPS://GPS.AFSPC.AF.MIL
MILITARY ALTERNATE - JOINT SPACE OPERATIONS CENTER, DSN 276-3526. COMM 805-606-3526.
JSPOCCOMBATOPS@US.AF.MIL
2022086 NOTICE ADVISORY TO NAVSTAR USERS (NANU) 2022086 NANU TYPE: GENERAL
*** GENERAL MESSAGE TO ALL GPS USERS ***
On approximately 27 OCT 2022, SVN49 will resume transmitting L-band utilizing PRN28; at L-band activation, SVN49/PRN28 will be unusable until further notice (additionally, no broadcast almanacs will include SVN49/PRN28 until further notice).
*** GENERAL MESSAGE TO ALL GPS USERS ***

POC: CIVILIAN - NAVCEN AT 703-313-5900, HTTPS://WWW.NAVCEN.USCG.GOV
MILITARY - GPS OPERATIONS CENTER at HTTPS://GPS.AFSPC.AF.MIL/GPSOC, DSN 560-2541,
COMM 719-567-2541, gpsoperationscenter@us.af.mil, HTTPS://GPS.AFSPC.AF.MIL
MILITARY ALTERNATE - JOINT SPACE OPERATIONS CENTER, DSN 276-3526. COMM 805-606-3526.
JSPOCCOMBATOPS@US.AF.MIL
2022104 NOTICE ADVISORY TO NAVSTAR USERS (NANU) 2022104 NANU TYPE: GENERAL
*** GENERAL MESSAGE TO ALL GPS USERS ***
Please disregard NANU 2022101. Please reference NANU 2022103 instead.
*** GENERAL MESSAGE TO ALL GPS USERS ***

POC: CIVILIAN - NAVCEN AT 703-313-5900, HTTPS://WWW.NAVCEN.USCG.GOV
MILITARY - GPS OPERATIONS CENTER at HTTPS://GPS.AFSPC.AF.MIL/GPSOC, DSN 560-2541,
COMM 719-567-2541, gpsoperationscenter@us.af.mil, HTTPS://GPS.AFSPC.AF.MIL
MILITARY ALTERNATE - JOINT SPACE OPERATIONS CENTER, DSN 276-3526. COMM 805-606-3526.
JSPOCCOMBATOPS@US.AF.MIL
2023042 NOTICE ADVISORY TO NAVSTAR USERS (NANU) 2023042 NANU TYPE: GENERAL
*** GENERAL MESSAGE TO ALL GPS USERS ***
On approximately 14 AUG 2023, SVN44 will resume transmitting L-band utilizing PRN22.

On 10 AUG 2023, GPS will transition SVN44 (PRN22) into the broadcast almanac for all satellites. The almanac transition, accomplished one satellite at a time, will require approximately 24 hours to complete. Before, during, and after transition SVN44 (PRN22) will remain unusable until further notice. Future NANUs will notify users of any changes to the above stated status.
*** GENERAL MESSAGE TO ALL GPS USERS ***

POC: CIVILIAN - NAVCEN AT 703-313-5900, HTTPS://WWW.NAVCEN.USCG.GOV
MILITARY - GPS WARFIGHTER COLLABORATION CELL at HTTPS://GPS.AFSPC.AF.MIL/GPSOC, DSN 560-2541,
COMM 719-567-2541, gpsoperationscenter@us.af.mil, HTTPS://GPS.AFSPC.AF.MIL
MILITARY ALTERNATE - JOINT SPACE OPERATIONS CENTER, DSN 276-3526. COMM 805-606-3526.
JSPOCCOMBATOPS@US.AF.MIL
2024014 NOTICE ADVISORY TO NAVSTAR USERS (NANU) 2024014 NANU TYPE: GENERAL
*** GENERAL MESSAGE TO ALL GPS USERS ***
The Space Force?s 2d Space Operations Squadron (2 SOPS) and the National Geospatial Intelligence Agency?s Global Navigation Satellite System Division (SFNG) worked collaboratively to deliver an updated WGS 84 reference frame to worldwide users of GPS.

NGA is responsible for maintaining the World Geodetic System 1984 (WGS 84) Terrestrial Reference frame which is used by the U.S. Department of Defense for its geolocation needs. In order to ensure adherence to international standards, facilitate interoperability with other GNSS, and satisfy US agreements and public commitments, NGA aligns the WGS 84 Terrestrial Reference Frame (TRF) to the International Terrestrial Reference Frame (ITRF) as closely as possible. In this case, alignment involves updating both the positions of the GPS monitor stations which define the WGS 84 TRF as well as the Antenna Phase Center Offsets of the GPS satellites as contained in the IGS20 ANTEX file.

On 07 January 2024, 2 SOPS and NGA adopted the new IGS20 ANTEX values at virtually the same time, ensuring that NGA?s orbit products and the operational GPS constellation remain consistent. As of 04 March 2024, both 2 SOPS and NGA have adopted the newly updated GPS monitor station locations completing the implementation of the new WGS 84 realization. This new WGS 84 realization, WGS 84 (G2296) is aligned to both the ITRF2020, the most recent ITRF realization, and the IGS20, the frame used by the International GNSS Service.

These updates represent an improvement in positioning for high accuracy users and ensures that the United States maintains its public commitment that WGS 84, the implicit reference frame for all users of GPS, remains consistent with international standards.

For more information on this update to WGS 84, see the document at the following link: https://earth-info.nga.mil/php/download.php?file=WGS%2084(G2296).pdf

POCs: geomatics@nga.mil, GPSOperationsCenter@us.af.mil
*** GENERAL MESSAGE TO ALL GPS USERS ***

POC: CIVILIAN - NAVCEN AT 703-313-5900, HTTPS://WWW.NAVCEN.USCG.GOV
MILITARY - GPS WARFIGHTER COLLABORATION CELL at HTTPS://GWCC-WS.CCE.AF.MIL/GPSOC, DSN 560-2541,
COMM 719-567-2541, gpsoperationscenter@us.af.mil, HTTPS://GWCC-WS.CCE.AF.MIL
MILITARY ALTERNATE - JOINT SPACE OPERATIONS CENTER, DSN 276-3526. COMM 805-606-3526.
JSPOCCOMBATOPS@US.AF.MIL
2024020 NOTICE ADVISORY TO NAVSTAR USERS (NANU) 2024020 NANU TYPE: GENERAL
*** GENERAL MESSAGE TO ALL GPS USERS ***
On approximately 22 APR 2024, SVN49 will resume transmitting L-band utilizing PRN01; at L-band activation, SVN49/PRN01 will be unusable until further notice (additionally, no broadcast almanacs will include SVN49/PRN01 until further notice).
*** GENERAL MESSAGE TO ALL GPS USERS ***

POC: CIVILIAN - NAVCEN AT 703-313-5900, HTTPS://WWW.NAVCEN.USCG.GOV
MILITARY - GPS WARFIGHTER COLLABORATION CELL at HTTPS://GWCC-WS.CCE.AF.MIL/GPSOC, DSN 560-2541,
COMM 719-567-2541, gpsoperationscenter@us.af.mil, HTTPS://GWCC-WS.CCE.AF.MIL
MILITARY ALTERNATE - JOINT SPACE OPERATIONS CENTER, DSN 276-3526. COMM 805-606-3526.
JSPOCCOMBATOPS@US.AF.MIL