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gaia data release 3 documentation

5 Photometric data

5.3 BP/RP spectroscopic processing

Author(s): Giorgia Busso, Francesca DeAngeli

The processing of the BP/RP data consists in two steps: the removal from the spectra of additional flux, not due to the transit source, and the alignment of the spectra. The additional flux is due to the background and neighbour sources. The correction for the first is described in Section 5.3.1. The correction for the second takes into account parasitic sources inside the same transit window, but also from the tail of sources outside the window but close enough that they can contaminate it. This has not been yet activated in Gaia DR3. However a crowding evaluation has been performed, to determine whether a transit is crowded or not (see Section 5.3.2). This is useful to select the sources used for the calibration and in the validation process.

The last step is to apply a geometric calibration so that the spectra are aligned (see Section 5.3.3) to the sample corresponding to the same wavelength.