Ring heater changes in were done yesterday, alog68755: ETMX up from 1.3 to 1.7 W and ETMY down from 1.0 to 0.6 W in two steps.

As shown in alog68715 and alog68115, we expect that the lower peak is Y-arm mode-separation and higher frequency peak is X-arm mode-separation, decreasing RH should move these down in frequency. The aim of the move was to bring the peaks on-top of each other. Looking at the attached plots of these peaks, what happened doens't look like I expected.

Attachment one, 1 hour into lock, you can see the upper X-arm peak move up in frequency (traces: purple -> blue -> dark green) as the ring heater increases. This is opposite of what we expect. Did the peaks swap? I don't think so as the initial settings are the same as when Dan clearly identifies the peaks in alog68715. The lower Y arm peak maybe rotates and interacts the upper peak but it almost looks like it moves down in frequency (opposite of what we expect with RH decrease).

Attachment 2 is comparing 2 hours into lock for for the initial 1.3 and 1.0W ring heater to early this morning's 0.6 W and 1.7 W settings. Third attachment is all plots.

Circulating powers have not changed more than 5kW between these measurements. Squeezing has been on since the change so it's tricky to see the effect on high frequency noise using just DARM.

Forth attachment, reminder than although we don't have good ETM HWS channels now, we can see what Aidan's simulation expect the ETM curvature to be doing with these changes using channels H1:TCS-SIM_ETM{X,Y}_SURF_ROC_FULL_OUTPUT.