PS1 and astrometry:
Bertrand G. took the PS1 pipeline proper motions and did the mean proper motions of known SDSS quasars in 4x4deg fields. The mean proper motion (reflecting the deviation from an inertial frame),
showed a smooth pattern with an amplitude of ~10 mas/yr.

He will take half the QSO sample correct the other half and see what happens.
That seems to imply that the calibration to the QSO's should work well.
That, in turn, bring new motivation to identify all PS1 quasars by a mix of WISE colors
and variability. In particular, we will need to look at the regions of considerable extinction
at low latitude.  So, let's find quasars at |b|<15, to map the Galaxy.