Keita, Kiwamu,
This is a follow up of the previous investigation for the input pointing issue (alog 15028). We are concluding that the IM2 is the one which messed up the input pointing the other day before the temperate issue hit us.
According to a back-of-envelop calculation, this well explains why we had to move IM4 by 88 urad in pitch to get back to good alignment (alog 15063). Also, from the OSEM spectra, there is no obvious indication of the mirror sticking to the cage or something. Therefore we don't think this is an issue.
Here are summary:
The attached is trend of various relevant signals:
Here is the spectra of the OSEMS before and after the slip. The bold curves are the ones taken on Nov 10 and the thin curves are the ones from today. All the spectra from today are consistenly lower at low frequencies supposedly due to different seismic level. Also we are having a small bump at around 2 Hz today for some unknown reason. In any case, we don't see an obivous indication of the mirror touching the cage or OSEMs. Therefore we are concluding that IM2 is still healthy.
Hugh, Sheila
This doesn't seem to be the result of either Hugh's work last tuesday or stray light reflected off of PRM.
This slip in IM2 happened about 5 and a half hours after hugh's work, and about 5 hours before PRM was realinged.