I/XXX Distances of 2 Million stars in the Gaia DR1 Catalogue (Astraatmadja & Bailer-Jones 2016) =================================================================================================== Estimating distances from parallaxes. III. Distances of two million stars in the Gaia DR1 catalogue Astraatmadja T.L., Bailer-Jones, C.A.L. =TBD =================================================================================================== ADC_Keywords: Parallaxes, trigonometric ; Stars, distances ; Surveys Keywords: catalogs; methods: data analysis; methods: statistical; surveys; parallaxes; stars: distances Abstract: We infer distances and their asymmetric uncertainties for two million stars using the parallaxes published in the Gaia DR1 (GDR1) catalogue. We do this with two distance priors: A minimalist, isotropic prior assuming an exponentially decreasing space density with increasing distance, and an anisotropic prior derived from the observability of stars in a Milky Way model. We validate our results by comparing our distance estimates for 105 Cepheids which have more precise, independently estimated distances. For this sample we find that the Milky Way prior performs better (the RMS of the scaled residuals is 0.40) than the exponentially decreasing space density prior (RMS is 0.57), although for distances beyond 2kpc the Milky Way prior performs worse, with a bias in the scaled residuals of -0.36 (vs. -0.07 for the exponentially decreasing space density prior). We do not attempt to include the photometric data in GDR1 due to the lack of reliable colour information. Our distance catalogue is available at http://www.mpia.de/homes/calj/tgas distances/main.html. These should only be used to give individual distances. Combining data or testing models should be done with the original parallaxes, and attention paid to correlated and systematic uncertainties. Description: This is a catalogue of distances and their asymmetric uncertainties inferred from the parallaxes published in the Gaia DR1 catalogue. Two priors are used: The exponentially decreasing space density and the Milky Way prior. For the exponentially decreasing space density prior, two scale lengths are used: 110 pc and 1350 pc. The former is based on a fitting of the true distance distribution of a subset of the GUMS catalogue (Robin et al. 2012) which are limited to V < 11. This is the magnitude at which Tycho-2 is 99% complete. The latter is based on the same procedure but limited to G = 20.7, which is the expected limiting magnitude of Gaia. For the Milky Way prior, the parameters are described in Astraatmadja and Bailer-Jones (2016). We report the mode of the posterior PDF, the median, the 90% credible interval, and a standard deviation in distance which are calculated by scaling the 90% into 68.3%. The Cepheids data used for the validation of the results are included here as well. They are taken from Groenewegen (2013) and cross-matched with Hipparcos and/or Tycho by making a Simbad query of each Cepheids and finding the corresponding Hipparcos and/or Tyho identifier. The distances are inferred either by neglecting the systematic uncertainties of 0.3 mas (Gaia Collaboration et al. 2016) for reasons described in the paper, or by adding a systematic uncertainties of 0.3 mas in quadrature with the random parallax uncertainties. We provide both results here. File Summary: ----------------------------------------------------------------------------------------------------------------------------------------------------------------------- FileName Lrecl Records Explanations ----------------------------------------------------------------------------------------------------------------------------------------------------------------------- README.txt 1264 . This file tgas_dist_all_v01.csv 340 2057050 Distances and uncertainties of all TGAS sources, no systematics uncertainties included. tgas_dist_all_withsys_v01.csv 340 2057050 Distances and uncertainties of all TGAS sources, systematics uncertainties of 0.3 mas included. tgas_dist_cepheids_v01.csv 382 105 Same as above, but for a subset of TGAS containing Groenewenegen (2013) Cepheids. tgas_dist_cepheids_withsys_v01.csv 380 105 Same as above, but with systematics uncertainties of 0.3 mas included. ----------------------------------------------------------------------------------------------------------------------------------------------------------------------- Byte-by-byte Description of file: tgas_dist_all_v01.csv tgas_dist_all_withsys_v01.csv The values in columns 1--8 are copied directly from GDR1. See https://gaia.esac.esa.int/documentation/GDR1/datamodel/Ch1/tgas_source.html for details ----------------------------------------------------------------------------------------------------------------------------------------------------------------------- Bytes Format Units Label Explanations ----------------------------------------------------------------------------------------------------------------------------------------------------------------------- 1- 6 I6 --- HIPId Hipparcos identifier (hip) 8- 19 A12 --- Tycho2 Tycho 2 identifier (tycho2_id) 21- 39 I19 --- SourceId Source ID (source_id) (G2) 41- 58 F18.14 deg LDeg Galactic longitude at epoch 2015.0 (l) 60- 77 F18.14 deg BGed Galactic latitude at epoch 2015.0 (b) 79- 96 F18.14 mas varpi Absolute barycentric stellar parallax of the source at the reference epoch 98-113 F16.14 mas errVarpi Standard error of parallax (parallax_error) 115-120 F6.3 mag GMag G-band mean magnitude 122-135 F14.9 pc rMoExp1 Mode distance of the posterior, using the exponentially decreasing space density prior with L = 0.11 kpc 137-150 F14.9 pc r5Exp1 5th percentile of the posterior, using the exponentially decreasing space density prior with L = 0.11 kpc 152-165 F14.9 pc r50Exp1 50th percentile (i.e. the median) of the posterior, using the exponentially decreasing space density prior with L = 0.11 kpc 167-180 F14.9 pc r95Exp1 95th percentile of the posterior, using the exponentially decreasing space density prior with L = 0.11 kpc 182-195 F14.9 pc sigmaRExp1 Distance standard error, using the exponentially decreasing space density prior with L = 0.11 kpc 197-210 F14.9 pc rMoExp2 Mode distance of the posterior, using the exponentially decreasing space density prior with L = 1.35 kpc 212-225 F14.9 pc r5Exp2 5th percentile of the posterior, using the exponentially decreasing space density prior with L = 1.35 kpc 227-240 F14.9 pc r50Exp2 50th percentile (i.e. the median) of the posterior, using the exponentially decreasing space density prior with L = 1.35 kpc 242-255 F14.9 pc r95Exp2 95th percentile of the posterior, using the exponentially decreasing space density prior with L = 1.35 kpc 257-270 F14.9 pc sigmaRExp2 Distance standard error, using the exponentially decreasing space density prior with L = 1.35 kpc 272-285 F14.9 pc rMoMW Mode distance of the posterior, using Milky Way Prior 287-300 F14.9 pc r5MW 5th percentile of the posterior, using Milky Way Prior 302-315 F14.9 pc r50MW 50th percentile (i.e. the median) of the posterior, using Milky Way Prior 317-330 F14.9 pc r95MW 95th percentile of the posterior, using Milky Way Prior 332-345 F14.9 pc sigmaRMW Distance standard error, using Milky Way Prior Byte-by-byte Description of file: tgas_dist_cepheids_v01.csv tgas_dist_cepheids_withsys_v01.csv Columns 1--23 are exactly as tgas_dist_all_v01.csv and are directly copied from that file. The subsequent columns are copied directly from Groenewegen (2013). A more detailed description can be found here: http://cdsarc.u-strasbg.fr/viz-bin/Cat?J/A%2bA/550/A70 as well as here: http://adsabs.harvard.edu/abs/2013A%26A...550A..70G ----------------------------------------------------------------------------------------------------------------------------------------------------------------------- Bytes Format Units Label Explanations ----------------------------------------------------------------------------------------------------------------------------------------------------------------------- 1- 6 I6 --- HIPId Hipparcos identifier (hip) 8- 19 A12 --- Tycho2Id Tycho 2 identifier (tycho2_id) 21- 39 I19 --- SourceId Source ID (source_id) (G2) 41- 58 F18.14 deg LDeg Galactic longitude at epoch 2015.0 (l) 60- 77 F18.14 deg BGed Galactic latitude at epoch 2015.0 (b) 79- 96 F18.14 mas varpi Absolute barycentric stellar parallax of the source at the reference epoch 98-113 F16.14 mas errVarpi Standard error of parallax (parallax_error) 115-120 F6.3 mag GMag G-band mean magnitude 122-135 F14.9 pc rMoExp1 Mode distance of the posterior, using the exponentially decreasing space density prior with L = 0.11 kpc 137-150 F14.9 pc r5Exp1 5th percentile of the posterior, using the exponentially decreasing space density prior with L = 0.11 kpc 152-165 F14.9 pc r50Exp1 50th percentile (i.e. the median) of the posterior, using the exponentially decreasing space density prior with L = 0.11 kpc 167-180 F14.9 pc r95Exp1 95th percentile of the posterior, using the exponentially decreasing space density prior with L = 0.11 kpc 182-195 F14.9 pc sigmaRExp1 Distance standard error, using the exponentially decreasing space density prior with L = 0.11 kpc 197-210 F14.9 pc rMoExp2 Mode distance of the posterior, using the exponentially decreasing space density prior with L = 1.35 kpc 212-225 F14.9 pc r5Exp2 5th percentile of the posterior, using the exponentially decreasing space density prior with L = 1.35 kpc 227-240 F14.9 pc r50Exp2 50th percentile (i.e. the median) of the posterior, using the exponentially decreasing space density prior with L = 1.35 kpc 242-255 F14.9 pc r95Exp2 95th percentile of the posterior, using the exponentially decreasing space density prior with L = 1.35 kpc 257-270 F14.9 pc sigmaRExp2 Distance standard error, using the exponentially decreasing space density prior with L = 1.35 kpc 272-285 F14.9 pc rMoMW Mode distance of the posterior, using Milky Way Prior 287-300 F14.9 pc r5MW 5th percentile of the posterior, using Milky Way Prior 302-315 F14.9 pc r50MW 50th percentile (i.e. the median) of the posterior, using Milky Way Prior 317-330 F14.9 pc r95MW 95th percentile of the posterior, using Milky Way Prior 332-345 F14.9 pc sigmaRMW Distance standard error, using Milky Way Prior 347-355 A9 --- CepName Cepheid name 357-366 A10 --- HIPId Hipparcos identifier (hip) 368-379 A12 --- Tycho2Id Tycho 2 identifier (tycho2_id) 381-387 F7.1 pc rCep Cepheid distance 389-394 F6.1 pc sigmaRCep1 Error in the fit on rCep 396-401 F6.1 pc sigmaRCep2 Error based on Monte-Carlo simulation on rCep Author's address: Tri L. Astraatmadja =========================================================================================================== (End) Tri L. Astraatmadja [DTM, Carnegie Institution for Science] 28-Sep-2016