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gaia data release 3 documentation

14.5 Multidimensional analysis

14.5.2 Radial velocities

Figure 14.64: Global distribution on radial velocity against GRVS (panel a), and G (panel b). The RVS is complete down to GRVS14, but extends to fainter magnitudes in G for a few potentially spurious sources.
Figure 14.65: Faint stars (16<G<19), with (GRVS-G)<-3 difference, but with a finite radial velocity assigned.

The global distribution of radial velocity against G band magnitudes is shown in Figure 14.64. While the distribution is complete down to GRVS14, there are a few sources fainter than G=16 that are also assigned a radial velocity. For these faint sources (16<G<19), the discrepancy between the two G bands is quite large, and in Figure 14.65, we show the 874 sources where (GRVS-G)<-3. For a few sources, there is as much as a 6 magnitude discrepancy. The radial velocity distribution for these sources is fairly Gaussian-like, and thus not unusual. Additionally, on the sky the sources are mostly confined to the midplane and towards the Galactic Centre, but otherwise uniformly distributed above and below the Galactic plane. However, compared to Gaia DR2, many of these sources were assigned a pseudocolour (astrometric_params_solved=95) in Gaia DR3. A large (GRVS-G) could indicate contamination from nearby bright stars (affecting the RV estimation) but also (for the faintest GRVS) an undersubtraction of the background. While these 874 sources have not been filtered from the RV sample, we recommend users urge caution while using radial velocity where (GRVS-G)<-3.