You are here: Home / USNO / Precise Time / GPS / GPS Timing Data and Information
The USNO websites,,,,,, and are undergoing modernization efforts. The expected completion of the work and the estimated return of service is the first half of 2022, subject to change due to potential impacts of COVID-19.

GPS Timing Data and Information

maintained by U.S. Naval Observatory

Coordinated Universal Time (UTC) Time Step (Leap Second)

After December 31st, 2016, GPS will be ahead of UTC by eighteen (18) seconds.


Dual-frequency GPS Data in RINEX format from the CDDIS data ftp server

  1. Yesterday's RINEX observation files for USNO receivers (in UNIX compressed format)
  2. Note: This data ftp service and these receivers are not controlled by USNO
  3. RINEX format conversion code (in C): to CGGTTS format and to CGGTTS and USNO formats


Timing Data for Individual GPS Satellites (Single frequency C/A code)

  1. Most recent 1 Day
  2. Most recent 7 Days    [UNIX compressed format]   [PC zipped format]
  3. Most recent 30 Days  [UNIX compressed format]   [PC zipped format]
  1. Most recent 1 Day
  2. Most recent 7 Days   [UNIX compressed format]  [PC zipped format]
  3. Most recent 30 Days [UNIX compressed format] [PC zipped format]
  • GPS Time vs. UTC via USNO Master Clock

  1. Most recent 30 Days
  2. Most recent 180 days

Notice Advisories to NAVSTAR Users (NANUs)


General GPS Information


Links to Other GPS Data Sources

USNO Master Clock Time
Javascript must be Enabled