The Global Positioning System (GPS) is a radionavigation system that is available worldwide. GPS signals are broadcast from a constellation of 24 or more earth orbiting satellites. Because the GPS signals are derived from the atomic frequency standards on board each satellite, they are widely used as a reference for time synchronization and frequency calibration. You can use the archive to quickly check the status of the GPS constellation on any given date.

NIST continuously monitors the GPS signals its laboratories in Boulder, Colorado and compares the frequency standard onboard each satellite to the NIST frequency standard. Commercially available GPS receivers often provide a 1 pulse per second (pps) timing output, and standard frequencies such as 1, 5, and 10 MHz. Properly designed GPS receivers can provide traceability to the national time and frequency standards maintained by NIST, and the archived data available here can be used to support claims of measurement traceability through the use of GPS, because the performance of each satellite is listed with respect to UTC(NIST). Click here to read more about using GPS receivers as a traceable measurement reference.

To view archived GPS data select the month, day, and year (yesterday's date will be selected by default), and then click the "Get Data" button. The archive is updated every 24 hours. Data from the previous day are added to the archive at about 1600 UTC.