Red markers indicate stars brighter than magnitude 13: these get downlinked from Gaia as small image

The job of the Sky Mapper is to detect stars entering Gaia s field-of-view as the satellite slowly rotates. There s one column of Sky Mapper CCD detectors for each of the two telescopes, in order to keep track of which star is coming from which telescope when the two beams are combined onto Gaia s big camera.
In normal operations, the Sky Mapper is continuously operating, but the image data are not transmitted back to Earth like this. Instead, Gaia s on-board computers analyse the data stream on the fly to detect the point sources, and to prepare small tracking windows which follow the stars as they move across the main astrometric CCDs.
Red markers indicate stars brighter than magnitude 13: these get downlinked from Gaia as small images centred on the star. Yellow markers then indicate intermediate-brightness stars with magnitudes 13 16, while cyan markers circle the faintest stars, with magnitudes scrubs 16 20. For the fainter stars, only the brightness scrubs profile in the scanning direction is downlinked.
Meanwhile and also part of the commissioning activities, work is continuing to provide a better understanding of the source of the stray light contamination noticed earlier. Further tests have involved tilting the spacecraft to different scrubs angles with respect to the Sun to see how that might affect the amount of unwanted light reaching Gaia s detectors, and the heating of various payload elements to help drive off any residual water ice in the system. scrubs
Both actions require considerable time to plan and execute, and also to interpret the results and respond accordingly. We will provide a further update scrubs once we have analysed all of the information. Posted on behalf of Gaia project team. The new images were also featured today as "Image of the week" on the Gaia community pages. Comments 4 Comments
Thank you for the 3 April blog post. It has been too quiet since the stray light problem announcement, and I was beginning to worry. Very interesting to see an example star field and the many sophisticated ways it is being analyzed. It is inspiring to see how much careful thought scrubs has gone into the GAIA project.
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