GaiaData Release 1

Abstract

Context. Gaia is an ESA cornerstone mission launched on 19 December 2013 aiming to obtain the most complete and precise 3D map of our Galaxy by observing more than one billion sources. This paper is part of a series of documents explaining the data processing and its results for Gaia Data Release 1, focussing on the G band photometry. Aims. This paper describes the calibration model of the Gaia photometric passband for Gaia Data Release 1. Methods. The overall principle of splitting the process into internal and external calibrations is outlined. In the internal calibration, a self-consistent photometric system is generated. Then, the external calibration provides the link to the absolute photometric flux scales. Results. The Gaia photometric calibration pipeline explained here was applied to the first data release with good results. Details are given of the various calibration elements including the mathematical formulation of the models used and of the extraction and preparation of the required input parameters (e.g. colour terms). The external calibration in this first release provides the absolute zero point and photometric transformations from the Gaia G passband to other common photometric systems. Conclusions. This paper describes the photometric calibration implemented for the first Gaia data release and the instrumental effects taken into account. For this first release no aperture losses, radiation damage, and other second-order effects have not yet been implemented in the calibration.

TheGaiamission

“…3.3.1), a dedicated area of 7 + 7 CCDs in the focal plane devoted to the sky mappers of the preceding and following telescope, and a dedicated area of 62 CCDs in the focal plane where the two fields of view are combined onto the astrometric field (AF). The wavelength coverage of the astrometric instrument, defining the unfiltered, white-light photometric G band (for Gaia), is 330-1050 nm (Carrasco et al 2016;van Leeuwen et al 2016). These photometric data have a high signal-to-noise ratio and are particularly suitable for variability studies (Eyer et al 2016).…”

“…The calibration process delivers the actual photometric passbands and the physical flux and wavelength scales. The photometric processing for Gaia DR1 is described in Carrasco et al (2016), Riello et al (2016), ), van Leeuwen et al (2016. RVS pipeline.…”

GaiaData Release 1

“…The movement across scan for a full CCD transit can vary between ±4 across-scan pixels. We refer to Gaia Collaboration (2016b) and Carrasco et al (2016) for a more detailed description of the instrument and the data.…”

“…It is accompanied by three other papers describing specific aspects of the photometric processing in much more detail: a paper on the calibration principles (Carrasco et al 2016), one on the technical issues presented by the processing of the Gaia photometric data and on the solutions implemented ) and one on the extensive validation activities that preceded the release . Among the papers accompanying Gaia DR1, the two papers Eyer et al (2017) and Clementini et al (2016) show the huge potential and exquisite quality of the Gaia photometry.…”

SCALA: In situ calibration for integral field spectrographs

“…Thus, observations over just a few nights will be needed in order for the statistical errors for a new standard star to become smaller than the fundamental calibration uncertainty anticipated from SCALA. Once the fundamental flux calibration is established, any spectrophotometric instrument -SNIFS, STIS, Gaia (Carrasco et al 2016), WFIRST (Spergel et al 2015) -can transfer this system to fainter stars for use by large telescopes.…”