Estimating distances from parallaxes IV: Distances to 1.33 billion stars in Gaia Data Release 2

C. A. L. Bailer-Jones, J. Rybizki, M. Fouesneau, G. Mantelet, R. Andrae

Published 2018-04-26Version 1

For the vast majority of stars in the second Gaia data release, reliable distances cannot be obtained by inverting the parallax. A correct inference procedure must instead be used to account for the nonlinearity of the transformation and the asymmetry of the resulting probability distribution. Here we infer distances to essentially all 1.33 billion stars with parallaxes published in the second Gaia data release. This is done using a weak distance prior that varies smoothly as a function of Galactic longitude and latitude according to a Galaxy model. The irreducible uncertainty in the distance estimate is characterized by the lower and upper bounds of an asymmetric confidence interval. Although more precise distances can be estimated for a subset of the stars using additional data (such as photometry), our goal is to provide purely geometric distance estimates, independent of assumptions about the physical properties of, or interstellar extinction towards, individual stars. We analyse the characteristics of the catalogue and validate it using clusters. The catalogue can be queried using ADQL at http://gaia.ari.uni-heidelberg.de/tap.html (which also hosts the Gaia catalogue) as the table geometric_distance in the schema gaiadr2_complements. The catalogue will go live on or before 30 April. Before that you can access it as a set of CSV files from http://www.mpia.de/~calj/gdr2_distances.html.