Data Quality - Pointing Performance

SCIAMACHY's Line-of-Sight (LoS) pointing performance can be degraded due to spacecraft manoeuvres such as

• Stellar Fine Control Manoeuvre (SFCM): SCIAMACHY is operated in MEASUREMENT mode executing timelines.
• In-plane Orbit Control Manoeuvre (OCM): same as for SFCM
• Out-of-Plane OCM: SCIAMACHY is operated in MEASUREMENT IDLE mode, i.e. no timelines are executed. When SCIAMACHY continues execution of MPS driven timelines, the platform attitude might still be non-nominal such that small pointing inconsistencies could exist until the nominal mode has been accomplished.
• Collision avoidance manoeuvre: These are usually executed as a SFCM, i.e. SCIAMACHY is operated in MEASUREMENT mode executing timelines.

or


• On-board attitude maintenance: The rare cases of attitude maintenance, including associated tests, can also impact the quality of the SCIAMACHY pointing performance shortly after the event.
• Non-nominal platform attitude mode: This can either be the transition period before or after an orbit manoeuvre or triggered by a platform attitude anomaly.

Data Quality History - Pointing (2002-2007)

The columns labelled ’ABS_ORB’ and ’UTC’ indicate the orbit number and the UTC start time of the event. Note that in the case of orbit manoeuvres with attitude mode changes the LoS pointing uncertainty will start earlier at the time when the nominal Stellar Yaw Steering Mode (SYSM) is no longer applicable. This can amount up to a few orbits. Manouevre entries given in bold red occurred while SCIAMACHY was not in MEASUREMENT mode due to an instrument or platform anomaly.

Although it does not correspond to routine operations, also the manoeuvre record for the year 2002 is listed for completeness. Occasional generation of measurement data started in orbit 197 (14^th March 2002) with continuous execution of quasi-routine measurement schedules commencing with orbit 2204 (2^nd August 2002).

Select year: 2007 / 2006 / 2005 / 2004 / 2003 / 2002