GAIA Data Release 2 (GDR2)

Gaia Data Release 2 was released on the 25 April 2018. A description of the contents of Gaia DR2 is given below.

Content

overview of Gaia Data Release 2 in numbers

Total number of sources 1,692,919,135 1,142,679,769
Number of 5-parameter sources 1,331,909,727 2,057,050
Number of 2-parameter sources 361,009,408 1,140,622,719
Sources with mean G magnitude 1,692,919,135 1,142,679,769
Sources with mean GBP-band photometry 1,381,964,755
Sources with mean GRP-band photometry 1,383,551,713
Sources with radial velocities 7,224,631
Variable sources 550,737 3,194
Known asteroids with epoch data 14,099
Gaia-CRF sources 556,869 2,191
Effective temperatures (Teff) 161,497,595
Extinction (AG) and reddening (E(GBP-GRP)) 87,733,672
Sources with radius and luminosity 76,956,778

distribution of Gaia Data Release 2 sources in G-band magnitude

Percentile All 5-parameter 2-parameter
0.135% 11.6 11.4 15.3
2.275% 15.0 14.7 18.5
15.866% 17.8 17.4 19.8
50% 19.6 19.3 20.6
84.134% 20.6 20.3 21.0
97.725% 21.0 20.8 21.2
99.865% 21.3 20.9 21.4

Background of the data

Gaia DR2 data is based on data collected between 25 July 2014 (10:30 UTC) and 23 May 2016 (11:35 UTC), spanning a period of 22 months of data collection (or 668 days), as compared to Gaia DR1 which was based on observations collected in the first 14 months of Gaia's routine operational phase.

The reference epoch for Gaia DR2 is J2015.5 (compared to the J2015.0 epoch for Gaia DR1). Positions and proper motions are referred to the ICRS, to which the optical reference frame defined by Gaia DR2 is aligned. The time coordinate for Gaia DR2 results is the barycentric coordinate time (TCB).