I looked into IMC alignment changes from before we started the pump down, to the current position. What I found is that MC1 pointing has changed dramatically. Pitch is changed by 332urad, and yaw by 184urad, when comparing the optic as it hangs without any drive. MC2 has seen changes as well, but smaller, with ptich changed by 52urad and yaw 12urad.
The MC1 pointing changes reuslt in beam position changes of 5.3mm in pitch and 3mm in yaw, at 16m. Very signiicant.
| no drive to optics | change in optic position, 11/25 to 12/10, in um and urad | beam shift in position at 16m, in mm |
| MC1 - M3 | ||
| L | 1 | |
| P | 332 | 5.3 |
| Y | 184 | 2.9 |
| MC2 - M3 | ||
| L | -7 | |
| P | 52 | 0.8 |
| Y | 12 | 0.2 |