Mission Status numbers


Satellite distance from Earth (in km)  
Number of days having passed since 25 July 2014  
Number of days in mission extension  
OPERATIONS DATA (collected since 2014/07/25)
Volume of science data collected (in GB)  
Number of object transits through the focal plane  
Number of astrometric CCD measurements  
Number of photometric CCD measurements  
Number of spectroscopic CCD measurements  
Number of object transits through the RVS instrument  


The table above presents the current mission status. It is based on the predicted spacecraft ephemeris and data accumulated by the science Data Integrity and Accountability Checks (DIAC) service. These numbers are updated multiple times per day, dependent on the contact schedule with the satellite, the status of the operational pipeline and the digestion of these numbers into the mission database. They should be interpreted with some care:

  • Object transits refer to on-board detections. An object can be a genuine star (most of the time), but also an asteroid, a QSO, an unresolved external galaxy, a cosmic ray, a false detection, etc. Actually, an object refers to an allocated window which, in dense areas, can contain multiple astronomical (light) sources.
  • The numbers do not include virtual objects (VOs).
  • Astrometric measurements refer to the 62 astrometric CCDs and the 14 Sky-Mapper CCDs.
  • Photometric measurements refer to the 14 blue- and red-photometer CCDs.
  • Spectroscopic measurements refer to the 12 radial-velocity-spectrograph (RVS) CCDs.
  • The number of spectroscopic transits does not necessarily equal three times the number of object transits through the RVS instrument. For instance, not all focal-plane transits lead to three CCD transits (stars can move out of the CCD in the across-scan direction) and/or some science data might currently still be stored on board.