Differences between Gaia DR2 and Gaia EDR3 photometry: demonstration, consequences, and applications

TL;DR

This paper presents a new highly accurate photometric calibration combining Gaia DR2 and EDR3 data, demonstrating improved precision and exploring implications for astrophysical research.

Contribution

The study develops a novel calibration method for Gaia's combined photometric system using an enhanced spectrophotometric library, achieving unprecedented accuracy.

Findings

Residual dispersions of 3.4-8.7 mmag in calibration

Most accurate large-scale optical photometric system to date

Demonstrated applications and tests of the calibration

Abstract

We produce a new photometric calibration for the combined six-filter system formed by $Gaia$ DR2 + EDR3 $G$+$G_{\rm BP}$+$G_{\rm RP}$ using an improved STIS/HST spectrophotometric library with very red stars. The comparison between observed and synthetic photometry yields residual dispersions of just 3.4-8.7 mmag, resulting in the most accurate and precise whole-sky large-dynamic-range optical photometric system ever obtained. We include some tests and applications.