Attached are plots of ETMY OSEMS, pitch and yaw, ISI ST1 and ST2 location monitors and their residuals, and HEPI location monitors and their residuals. In all plots, the first change (if present) is due to disengaging HEPI, and the second change (if present) is due to the Idaho M6.4 earthquake.
Plot 4 shows that ETMY L2 signals become very steady after the HEPI change, and shift after the EQ, and remain in the changed position, and remain very steady, which I believe suggests that L2 is touching.
Plots attached are in the order I created them, while looking into why the ETMY optical lever in pitch is now sitting at -50.
- plot 1 - ETMY pitch/yaw signals
- plot 2 - ETMY ISI residuals
- plot 3 - ETMY ISI location monitors
- plot 4 - ETMY OSEMs
- plot 5 - ETMY HEPI location monitors and residuals
Attaching the RX/RY residualmons for all the BSC HEPIs over a similar window. The biggest shifts are about 40 urad, on the BS, most are less than 20 though. The ETMY shift is relatively small, about 7 urad in RX, more or less pitch for that SUS. Do we have any idea of how much pitch is allowed by the given the clearance in the eq stops?
Upon further zooming in, it looks like this effect is due to the IFO being unlocked (the first t-cursor in the attached plot), and not the HEPI state being changed (second t-cursor in the attached plot).
I suspect that much of the effect of the L2 OSEMS looking more 'staionary' is that we're no longer actuating the optic with angular control once we unlock. I do also note that in the pitch oplev, we see that there is a shift when the IFO is unlocked, but not any real shift when the HEPI is taken offline (yaw sees a shift for both), but the motion as seen by the oplev is higher, becasue the seismic platform just isn't as isolated.
Rahul is in process of taking TFs to confirm that even with the HEPI in READY we're not rubbing. He'll post those in a separate alog.
Thank you, Arnaud, for suggesting we have another look at this.
