cheryl.vorvick@LIGO.ORG - posted 14:32, Tuesday 03 October 2017 - last comment - 12:32, Wednesday 04 October 2017(38876)
angle change of HAM2 and HAM3 SEI
HAM2, RZ = -246urad
HAM3, RZ = -166urad
HAM2, RZ = -246urad
HAM3, RZ = -166urad
I don't know what would have caused this alignment shift but the CPS signals don't look real. At 16:48 UTC Oct 2, there is a shift in both HAMs 2 & 3 at the exact same moment. First attached image is the full time series trend for the CPS RZ location (nrad) for both chambers for the minute containing the shift. Otherwise, neither Hugh nor I have done anything with the chambers, they haven't been unlocked since the vent. I'm having a hard time imagining a physical event that would move these chambers in this way at the same time. Second plot shows the RZ locations for the last ten days. Other than the jump on Oct 2nd, they don't look like they have moved since being locked.
Adding:
The GS13s also don't seem to see anything. Third trend is the same time as the first, showing both CPS and GS13s for the chambers.
With the chambers locked we took the Sync chassis down to move some power around. There was not movement. The chassis is powered up again but will require more down time. We will make it brief.