Montegriffo, P.Bellazzini, M.Ángeli, F. DeSarro Baro, Luis Manuel2024-05-202024-05-202023-06-161432-0746https://doi.org/10.1051/0004-6361/202243709https://hdl.handle.net/20.500.14468/12475Gaia Data Release 3 provides novel ux-calibrated low-resolution spectrophotometry for '220 million sources in the wavelength range 330 nm ≤ λ ≤ 1050 nm (XP spectra). Synthetic photometry directly tied to a ux in physical units can be obtained from these spectra for any passband fully enclosed in this wavelength range. We describe how synthetic photometry can be obtained from XP spectra, illustrating the performance that can be achieved under a range of dierent conditions – for example passband width and wavelength range – as well as the limits and the problems aecting it. Existing top-quality photometry can be reproduced within a few per cent over a wide range of magnitudes and colour, for wide and medium bands, and with up to millimag accuracy when synthetic photometry is standardised with respect to these external sources. Some examples of potential scientic application are presented, including the detection of multiple populations in globular clusters, the estimation of metallicity extended to the very metal-poor regime, and the classication of white dwarfs. A catalogue providing standardised photometry for '2.2×108 sources in several wide bands of widely used photometric systems is provided (Gaia Synthetic Photometry Catalogue; GSPC) as well as a catalogue of '105 white dwarfs with DA/non-DA classication obtained with a Random Forest algorithm (Gaia Synthetic Photometry Catalogue for White Dwarfs; GSPC-WD).eninfo:eu-repo/semantics/openAccessjournal articlecatalogssurveystechniques: photometrictechniques: spectroscopicstars: generalGalaxy: general