Ultras

• Files available:
  • GPS-satellite orbit + clock files (IGS .sp3 format)
  • Earth-orientation files (IGS .erp format)
     
• Each file provides 48 hours of solutions:
  • 24 hours of post-processed solutions
  • 24 hours of predictions
  • These files are also available via anonymous ftp at ftp://maia.usno.navy.mil/GPS/ultras/
     
• File name indicates center date/time of 48-hr span
  • before date = post-processed
  • after date = predict
     
• Frequency/latency: produced every six hours, available three hours after center epoch.
   
• File names (by example):
   
  • usu15002_18.sp3: 48-hr orbit/clock file with center date GPS week 1500, day 2 (Tuesday), hour 18 (GPST)
    • general format: usuwwwwd_hh.sp3
       
  • Similarly, usu15002_18.erp