After seeing that stepping the ITM ring heaters up in common didn't make improvements to the IFO (alog 47851), I have made a step down in common. This means that we have to be watchful for any ITM violin modes to go bonkers, but so far (3000 sec after the step) things still seem okay for now.
Just before doing anything, Patrick took the IFO out of Observing for me, so that we can easily flag that this is when the change happened.
I followed the instructions in Danny's alog 47770, although the ITM ring heater guardians were already in the FILTER_RH_INPUT state, presumably because they needed to be there for a few days after the Saturday night test. I changed H1:TCS-ITMY_RH_INVERSE_FILTER_IN from 1.3 W to 1.1 W, and I changed H1:TCS-ITMX_RH_INVERSE_FILTER_IN from 0.4 W to 0.2 W. I think I'm a little confused as to what those really mean, since the requested and measured power for each segment on ITMY is going to about 1.2 W, not 1.1 W, and the requested and measured power for each segment on ITMX is going to about 0.3 W not 0.2 W. But, it's still a step down in power, roughly in common, so the step will still show us if this is the direction we want to go.
As soon as I had made the ring heater change, I remembered to turn on the AWG_LINES guardian injections for intensity, frequency, and 9 MHz RFAM. So, I won't have peak heights to compare to from before any changes happened, but the lines are at least going now, and we can see how they change from the start of the step to the end of the step, and back to nominal (if I go back to nominal). I requested the AWG_LINES guardian by hand to go to INJECTING, but later realized that I could have just done it with the ISC_LOCK guardian.
To then get the IFO back to Observing, I accepted the SDF diffs for LSC, PSLISS and one of the Beckhoff modules to let the excitations for my injections go through. I also had to uncomment the line in ISC_LOCK, so that it would think that the AWG_LINES guardian should be in the injecting state, not the idle state, so that the ISC_LOCK node would be happy with its subordinate. I also (while in the IDLE state of AWG_LINES, after having manual-ed there from INJECTING) changed the nominal of that guardian to be INJECTING, so that it would report OK, so that ISC_LOCK would report OK, so that we could go to Observe.
After these minor guardian shenanigans, and the SDF accepts, I put the IFO back into Observing. (Sorry Patrick - I should have let you know I was done and let you do any checks necesssary)
After ~75 minutes, the circulating powers are increasing (a very small amount), but the frequency and intensity noise coupling at 75 Hz are getting worse. In the spectra, red is the original hotter, and blue is the current cooler state.
Violin modes all seem okay for now.
Just made another step, setting ITMX filter input to 0 W, and ITMY filter input to 0.9 W. Both of these are -0.4 W from where they started earlier today.
The IFO is pretty much thermalized from the second ring heater step I took today. The arm circulating powers are going up, and they are getting closer to eachother - the Xarm power is increasing slightly faster than the Yarm power.
The frequency and intensity noise couplings in the bucket are certainly worse - we likely need to do some differential tuning next. PRCL coherence is much higher now than it was earlier, suggesting (as was a suspicion) that it is mostly just reporting frequency noise, not direct PRCL noise. The MICH and SRCL feedforward look like they could use some tuning, but that's not really going to be a good use of time until we've done a bit of differential tuning.
Georgia is going to keep stepping TCS gently around tonight, and is getting the script ready to look at the injected lines.