North-South station manoeuvres are approximately performed once a year. This time, thrusters firing to correct the satellite's North-South position will take about 38 minutes and, at the end, the spacecraft spin rate needs to be adjusted with a second short manoeuvre. During both manoeuvres, imaging continues. The image geometric quality will be significantly affected by the firing of the thrusters.

To assess the actual performance of the manoeuvre some time is needed.  Until the results for the spacecraft's new orbit and attitude are available, image processing will be performed on predictions made prior to the manoeuvres. Depending on the accuracy of these predictions and the size of the corrections necessary, the image geometric quality may be degraded up to 24 hours after the manoeuvre. The users will be notified, when the image processing is fully recovered from the effects of the manoeuvre.

The user is invited to assess the quality of any level 1.5 image by examining the quality flags provided in the Level 1.5 Trailer (Epilogue). The most relevant flag is 'NominalImage' in  the 'L15ImageValidity' array in the 'Image Production Stats Record' in the Level 1.5 Trailer (Epilogue). The 'NominalImage' flag indicates whether the Level 1.5 image is of nominal quality. TRUE indicates nominal.

Information on the structure of the Level 1.5 Trailer (Epilogue) can be found in the document MSG Level 1.5 Image Data Format Description

A detailed description on the use of quality fields in the Level 1.5 Image can be found in document MSG Level 1.5 Image Product - Quality Indicators

Back | Product and Service News