The IM alignments were adjusted many times in the commissioning ramp up to O2, so IMs have not had nominal values for some time, and DIAG_MAIN values were not consistant with the current IM values.
I adjusted IM1-3 alignments after taking some measurements during maintenance today, and in looking at the IM alignment history.
I saw the IM1 pitch had bee restored to the DIAG_MAIN value yesterday, and this was not a correct value.
The current nominal values for IM1-3 OSEM alignments, as deemed good on Dec 8th at 09:00UTC, after a discussion with Jenne, are:
| pitch | yaw | |
| IM1 | 180 | 1120 |
| IM2 | 608 | -320 |
| IM3 | 1961 | -2 |
These are also listed in the IM Nominal Alignment medm (IOO sitemap list), and are updated in the DIAG_MAIN code.
To check IM alignment:
- use the procedure in the "Recovering IM Alignment After ISI Trip" wiki page
13 day trend - beginning of plots is where IM nominal alignment was set - after that, multiple ISI trips - some drift away from nominal - IM1 pitch change and recovery
