Because the microseism is down to a level similar to what we saw over the summer, I asked Patrick to put the ISI's in the more wind tolerant 90 mhz blends. Wind is also low right now, but it can come up suddenly, while microseism takes days to rise. We also need more data about what conditions necessitate switching. After, Evan and Keita finished in the PSL, Patrick started relocking but was having troubles with the  green. Fiddling the TMS alignments fixed it, I looked to see if the ISI positions had changed. They haven't moved but I found something interesting.

Most of the ISIs all showed a relatively smooth switch from the 45 to 90 blends except for ETMY. ITMY is the first plot and is pretty consistent with all the other chambers, except ETMY. Patrick switched the X&Y blends at the same time , in the middle of the time span I grabbed in the plot. You can kind of tell because the ITMY location mon range gets a little smaller and there are fewer low frequency swings on X&Y, due to the lower gain peaking at higher frequency of the 90 blend. The other DOFs don't seem to see anything.

ETMY however shows a huge 30 micron shift in the Y direction (second plot), and is visible in all DOFs. This chamber was only running the 45mhz blend in the Y DOF, so only the Y blend got switched on this chamber, at about 21:48 UTC today. No idea why it should be any different from the other chambers, although BrianL did note a while ago that the ETMY STS is poorly centered (maybe relevant because the STS is used for sensor correction, so gets summed with the CPS signal before the blend). It would be good to get some time to see if this is repeatable and truly limited to ETMY or not.