# Gaia Data Release 1: Validation of the photometry

## TL;DR

This paper validates Gaia DR1 photometry by internal consistency checks and comparisons with external catalogs, revealing calibration accuracy down to 3 millimagnitudes and identifying systematic effects.

## Contribution

It provides a comprehensive validation of Gaia DR1 photometry, highlighting calibration accuracy and systematic effects affecting flux measurements.

## Key findings

- Photometric calibration accuracy as low as 3 mmag.
- Identification of systematic effects in flux calibration.
- Comparison limited by external catalog accuracies.

## Abstract

Aims. The photometric validation of the Gaia DR1 release of the ESA Gaia mission is described and the quality of the data shown. Methods. This is carried out via an internal analysis of the photometry using the most constant sources. Comparisons with external photometric catalogues are also made, but are limited by the accuracies and systematics present in these catalogues. An analysis of the quoted errors is also described. Investigations of the calibration coefficients reveal some of the systematic effects that affect the fluxes. Results. The analysis of the constant sources shows that the early-stage photometric calibrations can reach an accuracy as low as 3 mmag.