The Gaia focal plane (FPA) consists of 106 large-format CCDs arranged in seven rows, where all CCDs on a particular row are operated by a dedicated onboard computer, all seven in synchronisation. We thus designate each of these rows as CCD Row 1−7, as denoted in the schematic above. In the horizontal direction, the CCD array is split into 17 different CCD strips (from CCD strip “BAM/WFS” to “RVS3”). The CCDs are colour-coded according to the functional group that they fall into. The light grey colour is used to denote Wavefront Sensor devices (WFS), the darker grey for the Basic Angle Monitor (BAM) instrument, dark blue for the devices used for onboard detection (Sky Mappers CCDs: SM), light blue for the AF (Astrometric Field) CCDs, green for the BP (Blue Photometer), yellow for the RP (Red Photometer), and red for the RVS (Radial Velocity Spectrometer) CCDs. As can be observed, all CCD rows are not identical, but include different functionalities. For example, some rows contain RVS CCDs to collect object spectra during star transits, and some do not. All rows, however, do contain all of the common elements required for the autonomous detection, confirmation, astrometric measurement, and photometric measurement chain: SM, AF1, AF2-9 (commonly grouped as “AF”), BP, and RP CCDs. The total height of the FPA from CCD row 1 to 7 corresponds to the scan width of about 0.7° on the sky.
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