Robert, Sheila, Camilla, Corey
Today we moved the spot on PR2, which reduced the power measured at the HAM3 viewport and the appearance of the 48 Hz peak in DARM when the black glass is removed from that viewport.
In our first lock of the day, Robert removed black glass: 16:08 UTC, we took ~20 minutes of quiet time with the black glass removed, before loosing lock due to an earthquake.
We decided to move 42 urad based on the first screenshot shows the May move described in 77949, the arm powers improved in the first 42urad of PR3 yaw move After relocking we moved PR2 by 42 urad, while the IFO was thermalizing (screenshot). Ran the A2L script and got a few minutes of quiet time there, starting at 20:20-20:31 UTC. We then decided to take another step to see if we could reduce the power in the HAM2 beam further, we moved an additional 10urad on PR3 yaw, and saw a small decrease in the beam power. We re-ran A2L here (added values to lscparams and loaded guardian), and took some time with the illuminator on the viewport to check the height of the peak. Camilla noticed that the squeezing didn't look optimal, so she's running SQZ alignment and angle scans. There is some LSC coherence, mostly with PRCL. We will plan to add PRCL FF next week, and re tune MICH and SRCL.
Robert measured power in the beam exiting the HAM3 viewport at a few steps: the original position: 47 mW, -20 urad yaw: 28 mW; -42 urad 19 mW; -52 urad: 17mW.
Old alogs about this move:
- Attempt to move closer to center while unlocked (reverted): 77968
- First move, when the squeezer whistles/FC motion coincidentally appeared and made DARM noise bad: 77870
- reverting that move because of SQZ issue: 77895
- In lock move of PR2 spot: 77949
- reverting PR2 spot move: 78012
Operator note: We moved these beams using a script that moves sliders on several optics, so that ideally we should be able to relock without doing any significant alignment. For yaw, the script was recently adjusted so that it really should work well, for pitch there may be some manual alignment of PR2 + IM4 needed to get initial alignment to lock the X arm in IR.
