Gaia Data Release 1. The photometric data

Context. This paper presents an overview of the photometric data that are part of the first Gaia data release. <BR /> Aims The principles of the processing and the main characteristics of the Gaia photometric data are presented. <BR /> Methods The calibration strategy is outlined briefly and the main properties of the resulting photometry are presented. <BR /> Results Relations with other broadband photometric systems are provided. The overall precision for the Gaia photometry is shown to be at the milli-magnitude level and has a clear potential to improve further in future releases.