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The Operational Advisory (also known as a GPS Status Message) provides a summary of the status of the satellite constellation. The advisory is is divided into four parts: Header, Section One (1), Section Two (2), and Section Three (3). You may also visit our GPS Acronyms and Abbreviations page.

Section One

The header includes the title, subject, and the date. The date is represented in a format that includes the
two digit day (DD), the first three characters of the month (MMM), and the four digit year. Also included is the Julian day of the year.
This lists operational satellites by PRN number, assigned plane, and atomic clock in use.
Block I - This generation of satellites is no longer used.
Block II - This is the current generation of operational satellites.
PRNs - Pseudo Random Noise code is the unique identifying sequence code that each satellite produces.
Slot - This indicates what plane and slot the satellite is occupying. The "plane" is the satellite's orbit, and the "slot" is the position in the plane.
CS & RB= Cesium and Rubidium are the atomic clocks used on the satellites, as noted for each satellite.
Section Two
This contains a summary of current and recent advisories, forecasts, and general text messages. It is organized into scheduled Notice Advisory to Navstar Users (NANU) messages, Operations Advisories, and general text messages.
You may also read the various NANU abbreviations and descriptions or search for individual NANUs in the current year, or view our NANU Archives.
Section Three
This identifies the points of contact for additional technical and support information. You may contact the Navigation Information Service for further information and questions.

GPS Status Message