gdr2_contrib.geometric_distance

Description

The catalogue provides distances estimates (and uncertainties therein) for 1.33 billion stars over the whole sky brighter than about G=20.7. These have been estimated using the parallaxes (and their uncertainties) from Gaia data release 2. A Bayesian procedure was used involving a prior with a single parameter L(l,b), which varies smoothly with Galactic longitude and latitude according to a Galaxy model. The posterior is summarized with a point estimate (usually the mode) and a confidence interval (usually the 68% highest density interval). The estimation procedure is described in detail in the accompanying paper (link), which also analyses the catalogue content.

Columns

Name Type UCD Unit Description
source_id long meta.id Source identifier, identical to the Gaia-DR2 source_id
r_est double pos.distance pc Estimated distance
r_lo double stat.error
pos.distance
pc Lower bound on the confidence interval of the estimated distance
r_hi double stat.error
pos.distance
pc Upper bound on the confidence interval of the estimated distance
r_len double pos.distance pc Length scale used in the prior for the distance estimation
result_flag short =0 failed estimate (none of r_est, r_lo, r_hi are defined) =1 r_est is the mode (highest if the posterior is bimodal); r_lo/r_hi define the lower/upper limits of the highest density interval (HDI) containing 68% of the posterior probability =2 r_est is the median; r_lo/r_hi define the lower/upper limits of the equal-tailed interval (ETI), containing 68% of the posterior probability
modality_flag short no. of modes in the posterior (1 or 2)