As of Feb. 17, the pp200 GeV beams seem not colliding in the center of PXL detector. See the online hit density plot which shows a wave similar to the early days in Run14 AuAu 200GeV.

We request a fast offline production to look at the reconstructed vertex distributions. The vertex finder used was 3D fit VFMinuit vertex finder. One run 16048027 was analyzed

Events selected should satisfy

|Vz_TPC - Vz_VPD|<6cm  (after some offset adjustment to let this peak at zero because of the incomplete VPD calibration)
|Vz_TPC|<20cm

Red:  reference, TPC center position w.r.t the STAR global magnet system
Black:  fitted vertex center positions

All triggers
vpdmb-5 trigger only
All triggers but with refMult>8

The study shows the beam position is shifted in X by about +0.25cm and in Y by about -0.07cm w.r.t to the TPC center.

The Run15 PXL position w.r.t the TPC center is not known yet waiting for the alignment to be completed. From the Run14 measurement, the shifts in X,Y for PXL on TPC are both within 0.05cm. If we neglect this contribution, the observation shown above is also consistent with the observed hit density distributions.