Table 1
Statistical summary of the 2 million sources in the primary data set of Gaia DR1.
| All primary sources | Hipparcos subset | |||||||
| Quantity | 10% | 50% | 90% | 10% | 50% | 90% | Unit | |
|
|
||||||||
| Standard uncertainty in α (σα ∗ = σαcosδ) | 0.147 | 0.254 | 0.601 | 0.158 | 0.224 | 0.391 | mas | |
| Standard uncertainty in δ (σδ) | 0.140 | 0.233 | 0.530 | 0.150 | 0.218 | 0.378 | mas | |
| Standard uncertainty in ϖ (σϖ) | 0.242 | 0.322 | 0.644 | 0.229 | 0.283 | 0.499 | mas | |
| Standard uncertainty in μα ∗ (σμα ∗) | 0.500 | 1.132 | 2.671 | 0.035 | 0.064 | 0.129 | mas yr-1 | |
| Standard uncertainty in μδ (σμδ) | 0.441 | 0.867 | 1.957 | 0.031 | 0.056 | 0.109 | mas yr-1 | |
| Semi-major axis of error ellipse in position (σpos, max) | 0.203 | 0.319 | 0.753 | 0.196 | 0.263 | 0.475 | mas | |
| Semi-major axis of error ellipse in proper motion (σpm, max) | 0.715 | 1.322 | 3.189 | 0.038 | 0.069 | 0.137 | mas yr-1 | |
| Excess source noise (ϵi) | 0.299 | 0.478 | 0.855 | 0.347 | 0.572 | 1.185 | mas | |
| Number of field-of-view transits input to the solution (N) | 8 | 15 | 25 | 7 | 14 | 25 | ||
| Number of good CCD observations AL used in the solution (ngood) | 57 | 99 | 185 | 51 | 93 | 180 | ||
| Fraction of bad CCD observations AL (nbad/ (ngood + nbad)) | 0.0 | 0.0 | 2.0 | 0.0 | 0.0 | 1.8 | % | |
| Normalised difference to Hipparcos proper motion (ΔQ) | – | – | – | 0.33 | 2.35 | 11.32 | ||
| Magnitude in Gaia’s unfiltered band (G) | 9.27 | 11.04 | 12.05 | 6.84 | 8.28 | 9.70 | mag | |
Notes. Columns headed 10%, 50%, and 90% give the lower decile, median, and upper decile of the quantities for all 2 057 050 primary sources, and for the subset of 93 635 sources in common with the Hipparcos catalogue (van Leeuwen 2007a). See footnote 7 for the definition of good and bad CCD observations.
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