For help on how to understand and/or interpret an Operational Advisory message, please visit our tutorial page.

Format of the messages

Almanacs, Operational Advisories, and NANUs are available for download in two formats:

1. the original format in which the files are produced (.alm, .al3., .nnu, .oa1, and .sof)
2. plain text (.txt)

OPS Advisories (GPS Status)

• Current Operational Advisories - .oa1, .txt

Almanacs (YUMA & SEM)

• Current YUMA Almanac - .alm, .txt
• Current SEM Almanac - .al3, .txt
• Definition of a YUMA Almanac can be found in the current version of Navstar GPS Control Segment to User Support Community Interfaces, ICD- GPS-240. You can find the document on the GPS Technical References page.
• Definition of a SEM Almanac can be found in the current version of Navstar GPS Control Segment to User Support Community Interface, ICD- GPS-240. You can find the document on the GPS Technical References page.

NANUs

• Current NANU - .nnu, .txt
• Information on NANUS, including abbreviations, descriptions, and examples, can be found in the current version of Navstar GPS Control Segment to User Support Community Interfaces, ICD- GPS-240. You can find the document on the GPS Technical References Page.
• To search for current year NANUS, click HERE for the Archives page, select GPS, then select NANU, enter the current year, and click search.
• Subscribe to the GPS Status Message and/or the NANU E-mail distribution list

SATELLITE OUTAGE FILE (SOF)

• Current SOF - .sof, .txt
• Definition of the SOF can be found in the current version of Navstar GPS Control Segment to User Support Community Interfaces, ICD- GPS-240. You can find the document on the GPS Technical References page. Higher priority GPS Control Station operations may delay development and publication of the SOF after release of a NANU.

ARCHIVES

• Almanac, NANU, and Ops Advisory Archives, sorted by year (.alm, .al3, .nnu, and .oa1 extensions)