GOMOS CAL/VAL

Cal/Val

The GOMOS Cal/Val Plan addressed Cal/Val activities undertaken to ensure the generation of high quality products and definitive validation of the products after launch.

Download the GOMOS Calibration and Algorithms Verification Plan for more detail.

Calibration Activities

Typical Routine Calibration sequence

Seven consecutive orbits per month were acquired with the GOMOS instrument in different monitoring modes:

  • 1 orbit in SSM mode. The brightest stars had to be chosen (this could not be done automatically by Starsel). At least six stars in dark limb (including at least three in eclipse) and three stars in bright limb.
     
  • 2 orbits in UNI mode, one at 10 km and one at 30 km altitude. The start times and the durations were always the same. The integration time was 0.5 s except for the last observation of the orbit. The azimuth was always equal to 30°. The location of the SATU windows ws always the same.
     
  • 2 orbits in LIN mode, from 300 to 100 km altitude. The brightest stars had to be chosen (this cannot be done automatically by Starsel). At least six stars in dark limb (including at least three in eclipse) and three stars in bright limb. The integration time was 0.25 s for the first orbit and 0.5 s for the second one.
     
  • 2 orbits in OCC with as much Dark Sky Area (DSA) acquisitions as possible. The altitude range was 300 to 200 km for the first orbit and 300 to 0 km for the last orbit.

Due to different needs, this sequence changed during the mission.

Download the Envisat Phase E Cal/Val Acquisition Plan for more detail.

Validation Activities