Synthetic LSST magnitudes derived from Gaia XP spectra

Oleksandra Razim

LSST magnitudes will span as faint as rmag ~ 24.7 for single-visit observations and ~27.5 for 10-year stacked images. These magnitudes will enable not only high-quality measurements of stellar parameters, but also precise modelling of the Milky Way evolution and its structure for at least up to ~100 kpc. 
In this work, we present a catalogue of synthetic LSST magnitudes, obtained from Gaia XP spectra. We produce magnitudes for ~220 million sources, most of which have Gaia Gmag<17.5. This catalogue can be used for investigating the possibilities that the LSST photometry will provide, and in the future, it will make possible joined usage of the LSST and Gaia observations, which will expand the magnitude and distance range so that they included the stars in the Solar neighbourhood, too bright to be observed by the LSST.
We also present a calibration procedure for the Gaia XP spectra, that uses SDSS Stripe 82 precise photometry to correct some of the systematic biases of Gaia. Using SDSS Stripe 82 dataset for estimation of the resulting photometric precision of the synthetic magnitudes, we found that the mean overall residual of the magnitudes equals ~0.0004 for griz bands and ~0.014 for the u band, and the overall scatter of residuals is less than 0.01 for griz bands and ~0.1 for the u band.


This talk will be given in the Rubin Science Medley session.


Career Stage: 
Post Doc