Improving LSST Photometric Calibration with Gaia Data

Abstract

We consider the possibility that the Gaia mission can supply data which will improve the photometric calibration of LSST. After outlining theLSST calibra- tion process and the information that will be availablefrom Gaia, we explore two options for using Gaia data. The first is touse Gaia G-band photometry of selected stars, in conjunction withknowledge of the stellar parameters Teff, log g, and AV, and in somecases Z, to create photometric standards in the LSST u, g, r, i, z, andy bands. The accuracies of the resulting standard magnitudes are foundto be insufficient to satisfy LSST requirements when generated from mainsequence (MS) stars, but generally adequate from DA white dwarfs (WD).The second option is combine the LSST bandpasses into a synthetic Gaia Gband, which is a close approximation to the real Gaia G band. Thisallows synthetic Gaia G photometry to be directly compared with actualGaia G photometry at a level of accuracy which is useful for bothverifying and improving LSST photometric calibration.