I/347 Distances to 1.33 billion stars in Gaia DR2 (Bailer-Jones+, 2018)
Estimating distances from parallaxes.
IV. Distances to 1.33 billion stars in Gaia data release 2.
Bailer-Jones C.A.L., Rybizki J., Fouesneau M., Mantelet G., Andrae R.
<Astron. J. 156, 58 (2018)>
=2018AJ....156...58B 2018AJ....156...58B
=2018yCat.1347....0B 2018yCat.1347....0B
ADC_Keywords: Surveys ; Stars, distances
Keywords: catalogs - Galaxy: structure - methods: statistical - stars: distances
Abstract:
For the 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 almost 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 analyze the
characteristics of the catalog and validate it using clusters.
Description:
The catalog can be queried using ADQL at
http://gaia.ari.uni-heidelberg.de/tap.html (which also hosts the Gaia
catalog) and downloaded from
http://www.mpia.de/~calj/gdr2_distances.html. Each file contains
200000 sources (except the last one) with a single header line. Total
size of all files is 114GB.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
gaia2dis.sam 143 1000 Estimating distances from parallaxes
(1331909727 sources)
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See also:
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/ApJ/833/119 : Distances of Gaia DR1 TGAS sources (Astraatmadja+, 2016)
Byte-by-byte Description of file: gaia2dis.sam
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Bytes Format Units Label Explanations
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1- 19 I19 --- Source Source identifier, identical to the
Gaia-DR2 source_id (id)
21- 35 F15.11 deg RAdeg Barycentric right ascension (ICRS)
at Ep=2015.5 (ra)
37- 51 F15.11 deg DEdeg Barycentric declination (ICRS)
at Ep=2015.5 (dec)
53- 73 F21.15 pc rest ? Estimated distance (r_est)
75- 95 F21.15 pc b_rest ? Lower bound on the confidence interval of
the estimated distance (r_lo)
101-121 F21.15 pc B_rest ? Upper bound on the confidence interval of
the estimated distance (r_hi)
124-139 F16.12 pc rlen Length scale used in the prior for the
distance estimation (r_len)
141 A1 --- ResFlag [0-2] Result flag (result_flag) (1)
143 I1 --- ModFlag [1/2] Number of modes in the posterior
(modality_flag)
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Note (1): Result flag as follows:
0 = failed estimate (r_est, r_lo, r_hi are all NaN)
1 = rest is the mode (highest if the posterior is bimodal);
brest/Brest define the lower/upper limits of the highest density
interval (HDI) containing 68% of the posterior probability
2 = rest is the median; brest/Brest define the lower/upper limits of the
equal-tailed interval (ETI), containing 68% of the posterior probability
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Acknowledgements:
Coryn Bailer-Jones, calj(at)mpia.de
References:
Bailer-Jones C.A.L., Paper I 2015PASP..127..994B 2015PASP..127..994B
Astraatmadja & Bailer-jones, Paper II 2016ApJ...832..137A 2016ApJ...832..137A
Astraatmadja & Bailer-jones, Paper III 2016ApJ...833..119A 2016ApJ...833..119A, Cat. J/ApJ/833/119
(End) Coryn Bailer-Jones [MPIA], Patricia Vannier [CDS] 07-Jun-2018