Overview of GAIA multi-color photometry

Gaia will obtain multi-color photometry for astrometric and astrophysical purposes. A photometry in five broad bands and with high angular resolution will be obtained after every astrometric observation of a star, especially for the sake of correcting slight astrometric chromaticity errors of the optical system. A separate. smaller telescope will obtain photometry in eleven passbands of medium width designed to serve the astrophysical analysis of the mission results. The mediumband photometry (MBP) has less angular resolution, but much longer effective integration time than the broad-band photometry (BBP).