Gaia Photometric Science Alerts
Abstract
Since July 2014, the Gaia mission has been engaged in a high-spatial-resolution, time-resolved, precise, accurate astrometric, and photometric survey of the entire sky. Aims: We present the Gaia Science Alerts project, which has been in operation since 1 June 2016. We describe the system which has been developed to enable the discovery and publication of transient photometric events as seen by Gaia. Methods: We outline the data handling, timings, and performances, and we describe the transient detection algorithms and filtering procedures needed to manage the high false alarm rate. We identify two classes of events: (1) sources which are new to Gaia and (2) Gaia sources which have undergone a significant brightening or fading. Validation of the Gaia transit astrometry and photometry was performed, followed by testing of the source environment to minimise contamination from Solar System objects, bright stars, and fainter near-neighbours. Results: We show that the Gaia Science Alerts project suffers from very low contamination, that is there are very few false-positives. We find that the external completeness for supernovae, , is dominated by the Gaia scanning law and the requirement of detections from both fields-of-view. Where we have two or more scans the internal completeness is at 3 arcsec or larger from the centres of galaxies, but it drops closer in, especially within 1 arcsec. Conclusions: The per-transit photometry for Gaia transients is precise to 1 per cent at , and 3 per cent at . The per-transit astrometry is accurate to 55 milliarcseconds when compared to Gaia DR2. The Gaia Science Alerts project is one of the most homogeneous and productive transient surveys in operation, and it is the only survey which covers the whole sky at high spatial resolution (subarcsecond), including the Galactic plane and bulge.
Cite
@article{arxiv.2106.01394,
title = {Gaia Photometric Science Alerts},
author = {S. T. Hodgkin and D. L. Harrison and E. Breedt and T. Wevers and G. Rixon and A. Delgado and A. Yoldas and Z. Kostrzewa-Rutkowska and Ł. Wyrzykowski and M. van Leeuwen and N. Blagorodnova and H. Campbell and D. Eappachen and M. Fraser and N. Ihanec and S. E. Koposov and K. Kruszyńska and G. Marton and K. A. Rybicki and A. G. A. Brown and P. W. Burgess and G. Busso and S. Cowell and F. De Angeli and C. Diener and D. W. Evans and G. Gilmore and G. Holland and P. G. Jonker and F. van Leeuwen and F. Mignard and P. J. Osborne and J. Portell and T. Prusti and P. J. Richards and M. Riello and G. M. Seabroke and N. A. Walton and Péter Ábrahám and G. Altavilla and S. G. Baker and U. Bastian and P. O'Brien and J. de Bruijne and T. Butterley and J. M. Carrasco and J. Castañeda and J. S. Clark and G. Clementini and C. M. Copperwheat and M. Cropper and G. Damljanovic and M. Davidson and C. J. Davis and M. Dennefeld and V. S. Dhillon and C. Dolding and M. Dominik and P. Esquej and L. Eyer and C. Fabricius and M. Fridman and D. Froebrich and N. Garralda and A. Gomboc and J. J. González-Vidal and R. Guerra and N. C. Hambly and L. K. Hardy and B. Holl and A. Hourihane and J. Japelj and D. A. Kann and C. Kiss and C. Knigge and U. Kolb and S. Komossa and Á. Kóspál and G. Kovács and M. Kun and G. Leto and F. Lewis and S. P. Littlefair and A. A. Mahabal and C. G. Mundell and Z. Nagy and D. Padeletti and L. Palaversa and A. Pigulski and M. L. Pretorius and W. van Reeven and V. A. R. M. Ribeiro and M. Roelens and N. Rowell and N. Schartel and A. Scholz and A. Schwope and B. M. Sipőcz and S. J. Smartt and M. D. Smith and I. Serraller and D. Steeghs and M. Sullivan and L. Szabados and E. Szegedi-Elek and P. Tisserand and L. Tomasella and S. van Velzen and P. A Whitelock and R. W. Wilson and D. R. Young},
journal= {arXiv preprint arXiv:2106.01394},
year = {2021}
}
Comments
26 pages, 26 figures, accepted for publication in Astronomy & Astrophysics