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gaia data release 3 documentation

5.5 Photometric Systems

5.5.2 Saturation correction

The saturation in the case of bright stars is shown in Figure 5.44. The impact of the saturation on the results of the G fluxes and magnitudes has decreased with respect to Gaia EDR2 because of changes in several steps of the calibrations. The figure shows the residuals when fitting G-HP as a function of V-I, or G-VT as a function of BT-VT and plotting them against the magnitude. Tycho-2 and Hipparcos data were combined to derive empirical corrections. The corrected magnitudes from the mean magnitudes in Gaia DR3, GXPcorr can be obtained with the following equations:

Gcorr-G = -0.09892+0.059G-0.009775G2+0.0004934G3 (5.51)
GBPcorr-GBP = -0.9921-0.02598G+0.1833G2-0.02862G3 (5.52)
GRPcorr-GRP = -14.94+14.41GRP-4.657GRP2+0.503GRP3 (5.53)

The G relationship should only be used in the range 2.0<G<8 mag, the GBP relationship only for 2.0<G<3.94 mag, and the GRP relationship only for 2.0<GRP<3.45 mag.

Figure 5.44: Saturation correction at the bright end for G (top), GBP (centre) and GRP (bottom) passbands.