Gaia Data Release 2 - Summary of the contents and survey properties

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Table 3

Basic performance statistics for Gaia DR2.

Data product or source type	Typical uncertainty
Five-parameter astrometry (position & parallax)	0.02–0.04 mas at G < 15
	0.1 mas at G = 17
	0.7 mas at G = 20
	2 mas at G = 21
Five-parameter astrometry (proper motion)	0.07 mas yr⁻¹ at G < 15
	0.2 mas yr⁻¹ at G = 17
	1.2 mas yr⁻¹ at G = 20
	3 mas yr⁻¹ at G = 21
Two-parameter astrometry (position only)	1–4 mas
Systematic astrometric errors (averaged over the sky)	<0.1 mas
Gaia-CRF2 alignment with ICRF	0.02 mas at G = 19
Gaia-CRF2 rotation with respect to ICRF	<0.02 mas yr⁻¹ at G = 19
Gaia-CRF2 alignment with ICRF	0.3 mas at G < 12
Gaia-CRF2 rotation with respect to ICRF	<0.15 mas yr⁻¹ at G < 12
Mean G-band photometry	0.3 mmag at G < 13
	2 mmag at G = 17
	10 mmag at G = 20
Mean G_BP- and G_RP-band photometry	2 mmag at G < 13
	10 mmag at G = 17
	200 mmag at G = 20
Median radial velocity over 22 months	0.3 km s⁻¹ at G_RVS < 8
	0.6 km s⁻¹ at G_RVS = 10
	1.8 km s⁻¹ at G_RVS = 11.75
Systematic radial velocity errors	<0.1 km s⁻¹ at G_RVS < 9
	0.5 km s⁻¹ at G_RVS = 11.75
Effective temperature T_eff	324 K
Extinction A_G	0.46 mag
Colour excess E(G_BP − G_RP)	0.23 mag
Radius	10%
Luminosity	15%
Solar system object epoch astrometry	1 mas (in scan direction)

Notes. The astrometric uncertainties as well as the Gaia-CRF2 alignment and rotation limits refer to epoch J2015.5 TCB. The uncertainties on the photometry refer to the mean magnitudes listed in the main Gaia DR2 catalogue.

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