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gaia data release 3 documentation

5.3 BP/RP spectroscopic processing

5.3.6 Catalogue of BP/RP spectra in Gaia DR3

In the Gaia DR3 release there are 219,224,825 sources with BP/RP mean spectra. This number is the result of the following selection criteria:

  • sources brighter than 17.65 in the G band, with more than 15 CCD transits and with reliable SSC values (see Sect. 8.2 of (Riello et al. 2021) for more details on the goodness of the SSCs). Sources with poor SSC values were filtered out unless included in the list itemized below;

  • about 500 sources used for the BP/RP data calibration (SPSSs and PVLs, see Section 5.6, plus some sources with emission lines);

  • about 100 000 white dwarf candidates;

  • about 17000 galaxies;

  • about 19000 ultra-cool dwarfs;

  • 900 objects used in the astrophysical parameters pipeline as the most representative sources for each of the 900 neurons of the self organising maps (see Section 11.3.12).

  • 9 solar analogues (see Section 8.3.7)

In Gaia DR3, one source (sourceId 5405570973190252288) has only the GRP mean spectrum, while all the others have both BP/RP mean spectra.

It is important to emphasize again that the processing of the spectra, whose outputs are the mean spectrum and the colour information (SSCs), is independent from the calibration of the integrated photometry (see Section 5.4). It may then happen for instance that a gold source, whose photometry has been calibrated using completed colour information, might have no photometry in one or more bands (because it has being discarded during the calibration) but it might have a mean spectrum.

Furthermore, not all continuous spectra have also the sampled representation, however this can be obtained from the continuous spectra using the GaiaXPy tool – see for GaiaXPy documentation and installation instructions. GaiaXPy can be also used to simulate Gaia spectra from an input absolute spectral energy distribution.