I don't think I had focussed the input arm cameras yet when Sheila made this log about moving CPs, https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=30979, so I offset CPY to see if I could see where the light was hitting. I could see a moving spot on an apparent table weight in front of the PR2 scraper baffle (screenshots show nominal and pitch of -150 on CPY, bright spot is at the very bottom of nominal image). However, I could not see it on the "swiss chese" baffle in front of HAM2 when I looked through a viewport, so it is likely dumped on the vacuum enclosure near HAM3 or the "eye" baffle between HAM3 and the long IMC tube, and from there reflects onto HAM3. Sheila's 0.1 Hz excitations did not show that this was a current problem. Nevertheless, from looking at the camera, I agree with her that a lower-scatter parking place is at CPY pitch < -70. This might also give us even more head room for some of the ~100 Hz scattering associated with vibration excitation of the input arm vacuum enclosure.
The reason I dont think it is a simple path off of PR3 is that the spot is quite large and diffuse.