end-of-mission SKY-AVERAGE ASTROMETRIC PERFORMANCE

Standard error in parallax (σπ), position at mid-epoch (σ0), and proper motion (σμ), versus G magnitude for an unreddened G2V star (V-IC = 0.75 mag, V-G = 0.16 mag). Units are μas for position and parallax and μas yr-1 for proper motion. The values are sky averages for a uniform stellar distribution; see this figure and this table for variations across the sky. For stars brighter than G = 12 mag, the average performance is quoted over the range G = 3-12 mag.

 

G   < 12   13 14 15 16 17 18 19 20
σ0 5.0 7.7 12.3 19.8 32.4 55.4 102 208 466
  σπ    6.7   10.3    16.5    26.6    43.6    74.5    137    280    627 
σμ 3.5 5.4 8.7 14.0 22.9 39.2 72.3 147 330

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