Today we have seen at least three examples that might make us want to return to trying 90 MHz centering. The first two screenshots attached show locklosses where we lost sideband buildups, which is usually a sign of misalignment of the BS or SRC. (We are currently using a combination of AS36I A+B for SRM control 26785 and AS36BQ for BS control). You can see that the BS yaw control signal drifts along with the sideband powers, and that there is clearly also a signal in the 90MHz Yaw signals, which might indicate we could use these sensors to prevent this kind of run away and lockloss.
The third one shows the lock that CHris and TJ left overnight last night, and you can also see sideband powers drifting a bit over the first couple hours of the lock, which is also tracked by some signal in 90 MHz yaw.
Here's the cavity pole fluctuation during the 4/26 overnight lock, monitored using Kiwamu's line tracking technique. After the initial transient it was stable within a few Hz. Looks like a favorable verdict on the new SRC1 WFS combinations.
