Fig 1.3.2.2.4.12.1: Nightside measurements and calibrations

When ENVISAT is in the nightside part of the orbit, SCIAMACHY mainly performs calibration measurements such as monitoring of the dark current by pointing into deep space.

Several nadir measurements using long integration times (up to 80 s) are also performed in the nightside part of the orbit.

These routine operations can also include daily, weekly or monthly calibration sequences, such as wavelength or radiometric calibration, scan mirror degradation monitoring etc.