Table 3
Properties of Gaia DR2 and external catalogues.
| Catalogue | NSources | PosErrmaxa | Effective resolution | ΔEpochmax | SysErrmaxb | Survey typec |
|---|---|---|---|---|---|---|
| (arcsec) | (arcsec) | (yr) | (arcsec) | |||
| Gaia DR2 | 1 692 919 135 | 0.1 | 0.4d | |||
| Pan-STARRS1 DR1 | 2 264 263 282 | 1.0 | ~1.1 | 18.02 | 0.18 | Dense |
| GSC 2.3 | 945 592 683 | 1.6 | ~2f | 62.79 | 0.63 | Dense |
| PPMXL | 910 468 688 | 1.342e | ~2f | 15.5 | 0.155 | Dense |
| SDSS DR9 | 469 029 929 | 10.0 | ~0.7f | 16.79 | 0.17 | Dense |
| URAT-1 | 228 276 482 | 0.429 | ~2.5f | 3.189 | 0.03 | Dense |
| 2MASS PSC | 470 992 970 | 1.21 | ~2.5 | 17.29 | 0.173 | Dense |
| allWISE | 747 634 026 | 35.944 | 6.1, 6.8, 7.4,12.0g | 5.47 | 0.055 | Dense |
| APASS DR9 | 61 176 401 | 2.359 | ~5 | 3.5 | 0.035 | Dense |
| HIPPARCOS2 | 117 955 | 0.1684 | ~0.3 | 24.25 | 0.2425 | Sparse |
| Tycho-2 | 2 539 913 | 0.254 | ~0.8 | 24.275 | 0.2475 | Sparse |
| RAVE 5 | 457 555h | 0.6i | 3.5j | 15.5i | 0.155 | Sparse |
Notes. (a) PosErrmax = max[max(RAerr), max(DECerr)]. (b) SysErrmax = PM ⋅ΔEpochmax∕5, see Sect. 3.2. (c)This classification determines the algorithm used to calculate the cross-match, see Sect. 2. (d) See Arenou et al. (2018), Sect. 2.2, for an analysis of the effective angular resolution of Gaia DR2. (e) The maximum of the position error refers to the propagated errors at J2000.0. (f) Effective resolution value is our best guess (see Sect. 4). (g) Angular resolution in the four bands W1, W2, W3, and W4. (h)RAVE contains multiple observations of the same source, which are identified with the same RAVEID and a different RAVE_OBS_ID. The number reported in this table is the number of RAVE distinct sources. (i) Assumed for cross-match calculation, see Sect. 3. (j)For RAVE 5, we used roughly half the size in the sky of the fiber diameter of the multi-object spectrograph 6dF that was used to observe the RAVE sources.
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