Improving LSST Photometric Calibration with Gaia Data

TL;DR

This paper explores how Gaia data can enhance LSST's photometric calibration by using Gaia G-band photometry of specific stars and creating synthetic Gaia G band measurements for calibration verification.

Contribution

It proposes two novel methods utilizing Gaia data to improve LSST photometric calibration, including standard star creation and synthetic band comparison.

Findings

Gaia G-band photometry of white dwarfs can serve as reliable standards.

Synthetic Gaia G band allows direct comparison for calibration verification.

Methods improve calibration accuracy but have limitations with main sequence stars.

Abstract

We consider the possibility that the Gaia mission can supply data which will improve the photometric calibration of LSST. After outlining the LSST calibra- tion process and the information that will be available from Gaia, we explore two options for using Gaia data. The first is to use Gaia G-band photometry of selected stars, in conjunction with knowledge of the stellar parameters Teff, log g, and AV, and in some cases Z, to create photometric standards in the LSST u, g, r, i, z, and y bands. The accuracies of the resulting standard magnitudes are found to be insufficient to satisfy LSST requirements when generated from main sequence (MS) stars, but generally adequate from DA white dwarfs (WD). The second option is combine the LSST bandpasses into a synthetic Gaia G band, which is a close approximation to the real Gaia G band. This allows synthetic Gaia G photometry to be directly compared with actual Gaia G photometry at a level of accuracy which is useful for both verifying and improving LSST photometric calibration.