Calibration of the photometric G passband for Gaia Data Release 1

Abstract

Context. On September 2016 the first data from Gaia were released (DR1). The first release included photometry for over 10^9 sources in the very broad G system. Aims. To test the correspondence between G magnitudes in DR1 and the synthetic equivalents derived using spectral energy distributions from observed and model spectrophotometry. To correct the G passband curve and to measure the zero point in the Vega system. Methods. I have computed the synthetic G and Tycho-2 BV photometry for a sample of stars using the Next Generation Spectral Library (NGSL) and the Hubble Space Telescope (HST) CALSPEC spectroscopic standards. Results. I have found that the nominal G passband curve is too blue for the DR1 photometry, as shown by the presence of a color term in the comparison between observed and synthetic magnitudes. A correction to the passband applying a power law in lambda with an exponent of 0.783 eliminates the color term. The corrected passband has a Vega zero point of 0.070$\pm$0.004 magnitudes.

Four-page letter, accepted for publication in A&A

References in corpus (5)

• The Gaia mission
• Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties
• The VLT-FLAMES Tarantula Survey XVI. The optical+NIR extinction laws in 30 Doradus and the photometric determination of the effective temperatures of OB stars
• Gaia data release 1: Principles of the photometric calibration of the G band
• Gaia data release 1, the photometric data

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