Seed high-proper-motion or high-parallax stars from NSC

[djschlegel]

Currently, we only have parallax and proper motion for stars with those parameters in Gaia DR2. We could also seed (and ideally re-fit) parallax + proper motion for stars not in Gaia (typically because they're fainter) identified by David Nidever's NSC DR2.

One such example is this high-parallax brown dwarf:
2MASS J03480772-602227
(ra, dec) = (57.030457, -60.376464)
type = T7
parallax = 120.1 +/- 1.8 mas
(pmra, pmdec) = (-279.7 +/- 0.6, -768.5 +/- 0.7)
https://www.legacysurvey.org/viewer?ra=57.0297&dec=-60.3774&layer=des-dr1&zoom=14