The FlatBlue+1 and FlatBlue+2 lamps are used for imaging screen flats.
The RMS is calculated from the master screen flat image pixel sample (2x2 binning) X: @200 @1800 and Y: @400 @800 covering the unvignetted area of chip1 and chip2.

DB Name: fors2_scrflat
TPL.ID: FORS2_img_cal_scrflat
QC1 DB parameter: sigma_master