14.3 Comparison to models 14.3.5 Radial velocities 14.3.7 Astrophysical parameters from GSP-Phot and GSP-Spec

14.3.6 Colour distributions

The median of the $G_{\mathrm{BP}}-G_{\mathrm{RP}}$ colour is computed in each HEALPix pixel and presented in Figure 14.48 in the magnitude range $17<G<18$ . We also consider median over the whole sky per magnitude bin, for Gaia DR3 and GOG20 in Figure 14.49 for three ranges of latitudes. At intermediate and faint magnitudes, the differences can be large in the Galactic plane and are clearly linked to the extinction. At higher latitudes, the model is in agreement with the data at the level of 0.1 mag. However at bright magnitudes ( $G<9$ at intermediate latitudes and towards the poles, $G<12$ in the plane), the data deviates from the values predicted by the model, showing a problem in the colour determination for those bright stars, although this discrepancy is slightly reduced compared to Gaia DR2.

Figure 14.48: Median of the $G_{\mathrm{BP}}-G_{\mathrm{RP}}$ colour computed in HEALPix pixels in Gaia DR3 (left), in GOG20 (middle) and their differences (right) in the magnitude range $17<G<18$ .

Figure 14.49: Difference of $G_{\rm BP}$ - $G_{\rm RP}$ colour (DR3-GOG20) as a function of magnitude, over the whole sky (circles), and in three latitude zones: plane (triangles), intermediate latitudes (crosses), poles (plus).

Summary of the results:

•

At high latitudes, model and data are in agreement at the level of 0.1 mag.
•

The differences between data and model can be large in the Galactic plane and are clearly linked to the extinction.
•

The colour determination of relatively stars ( $G$ $<$ 9) seems problematic, although this discrepancy is reduced compared to Gaia DR2.

gaia data release 3 documentation

14.3.6 Colour distributions