6.3.3 Straylight background

The RVS straylight background is measured using the same principles as the BP/RP background model (see Section 5.3.1). All the RVS Virtual Objects from the first month of the mission (28 days Ecliptic Pole Scanning Law) were processed off-line. The median flux value of each VO, which contains 1260 samples, was computed, to avoid contamination by cosmic rays and stellar spectra. The row fraction coordinate (out of RVS CCD rows 4-7) and heliotropic spin phase were also calculated. All the virtual objects belonging to the same cell are averaged to obtain a median value, removing outliers. A straylight map was constructed for each of the three RVS CCD strips using a grid of 2160 cells in the spin direction and 50 cells in the AC direction covering the four RVS CCD rows (see Figure 6.3). This map is used to correct all the Gaia DR2 data, neglecting any temporal variation.