Gaia Synthetic Photometry Catalogue (GSPC)

This is a catalogue of synthetic photometry generated from the Gaia BP/RP mean spectra in Data Release 3 and standardised using wide and reliable sets of external standard stars.Only sources that have BP/RP mean spectra in Gaia DR3 can be included in this catalogue. Individual magnitudes and fluxes are included only if Fσ_F > 30 in that passband, where F and σ_F are the flux and its uncertainty. Synthetic photometry is provided in a selection of photometric systems.Further details on the generation and composition of the catalogue are available in DR3-DPACP-93.

Known issues

Wrong units in SDSS and PS1 flux and flux error fields in table <code>gaiadr3.synthetic_photometry_gspc</code>

The units of the SDSS and PanSTARRS1 (PS1) flux and flux error fields in the Gaia DR3 table gaiadr3.synthetic_photometry_gspc (Gaia Collaboration, Montegriffo, et al., 2022) are W m−2 nm−1 but should read W m−2 Hz−1. The reason is that the SDSS and PS1 photometric systems use AB rather than Vega magnitudes. Only the units are wrong: the table and data are otherwise correct.

Error in the PS1 synthetic photometry in table <code>gaiadr3.synthetic_photometry_gspc</code>

Due to a bug in GaiaXPy (fixed in patch 1.2.4, released on the 9th of January 2023), the synthetic photometry for the standardized PanSTARRS1 y band (contained in the fields y_ps1_flux, y_ps1_flux_error and y_ps1_mag) has been generated without applying the flux offset mitigating the systematic effect at the faint end due to background issues (also referred to as hockey-stick, see Section 2.2.1 and equation 13 in Gaia Collaboration, Montegriffo, et al., 2022). The offset should have been applied to the synthetic flux and then propagated to the flux error and magnitude. However, no offset was applied.

The table gaiadr3.synthetic_photometry_gspc will not be fixed. However, correct synthetic photometry in the standardised PanSTARRS1 system can be generated using GaiaXPy (with version 1.2.4 or later) on spectra extracted from the Gaia archive.