Data Quality
During routine SCIAMACHY operations there are certain activities/events which will degrade the quality of the measurement data, such that these data shall not be used. Reasons for degraded measurement data can be
The thermal behaviour is disturbed by
The infrared detectors suffer most from such a disturbance. Therefore these detectors take longest to reach thermal equilibrium again. The table below summarizes the stabilization times for each of these events.
Event | Item |
Stabilization Time (hrs) |
ATC/TC readjustment | ||
TC Heater Power | Det 5 & 6 | 27 |
Det 7 & 8 | 48 | |
ATC Temperature Setpoints | OBM | 19 |
Recovery from a) | ||
HEATER-REFUSE (max. downtime > 15 hrs) |
OBM | 19 |
Det 1 - 6 | 42.5 | |
Det 7 & 8 | 58.5 | |
STANDBY (max. downtime > 6 hrs) |
OBM | 20 |
Det 1 - 6 | 43.5 | |
Det 7 & 8 | 59.5 | |
Cool-down in b) | ||
Nominal Decontamination | OBM | 20 |
Det 1 - 8 | 58 | |
Non-Nominal Decontamination | OBM | 20 |
Det 1 - 6 | 48 | |
Det 7 & 8 | 56 |
As long as the OBM and detector temperature stability has not been achieved, measurement data are of degraded quality. Detector temperatures and OBM temperatures are monitored on a weekly basis.
Whenever the PMD ADC has suffered from a SEU, the PMD measurement data may be correpted afterwards. They shall not be used until a PMD/ADC_SF calibration has been executed. This calibration is triggered by monitoring specific PMD parameters.
During manoeuvres of the spacecraft, the attitude control mode differs from that in nominal operations. Thus the pointing of the instrument will be disturbed. Whether pointing performance degradation has to be taken into account depends on the type of manoeuvre.
The entry in the Data_Quality_History table occurs manually.