Table 1
Simulation results of three different experiments comparing the parallax median between the stellar subset and the quasars.
| Parallax selection | ||||
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| 90% best | all | |||
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| Subset | Median [μas] | RSE [μas] | Median [μas] | RSE [μas] |
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| Experiment 1: clean quasar sample | ||||
| Stars | 872.1 ± 0.2 | 441.9 | 872.1 ± 0.2 | 613.5 |
| Quasars | 876.4 ± 2.0 | 1336.6 | 876.7 ± 2.5 | 2324.7 |
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| Experiment 2: with spurious proper motions | ||||
| Stars | 872.0 ± 0.2 | 442.0 | 872.0 ± 0.2 | 613.4 |
| Quasars | 876.7 ± 2.9 | 1644.7 | 877.7 ± 3.4 | 2676.3 |
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| Experiment 3: with 5% contamination | ||||
| Stars | 872.1 ± 0.2 | 441.9 | 872.0 ± 0.2 | 613.5 |
| Quasars | 871.7 ± 2.2 | 1429.2 | 872.0 ± 2.4 | 2452.9 |
Notes. “Stars” refers to the combined subset of Hipparcos and Tycho-2 sources. In each subset, statistics are given for the selection of 90% of the sources with the smallest individual formal uncertainties and for all sources together. The values given are the median (and its uncertainty from the bootstrap method) and the RSE dispersion of the parallax errors (estimated minus true).
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