As Jeff showed in 72627, CO2X delivered power has dropped 7% since May. At the start of May both CO2s were injecting 1.68W of annular CO2 power into the IFO but now CO2X is injecting 1.56W. CO2X laser power seems to be quickly decaying, see attached. We have been seeing this laser unlocking regularly and blaming the chiller 72653.

Expect that by adjusting H1:TCS-ITMX_CO2_LASERPOWER_POWER_IN (max central power) from 4.844 to 4.28 and re-requesting 1.15W for CO2X would inject the correct 1.68W for CO2X (as max laser power has decayed from 48.5W to 42.8W). We would need to check this and maybe re-run the calibration 66724 during Tuesday maintenance.

Current requested power in lscparams.py is tcs_nom_annular_pwr = {'X': 1.15, 'Y': 1.1}, calibrated for central.

Compared the HOM peaks at the below times, all for observing H1 that had been locked for 13 hours (can't compare prior to June as has 75W input), Can't seem much of a duiffernece apart from the x-arm peak moved between the end fo June and start of July. In 71284, Elenna showed the current state is different form April 2023.

• 2023/06/24 03:06:14 UTC June
• 2023/07/05 18:24:18 UTC July
• 2023/08/04 15:26:30 UTC Aug
• 2023/09/18 02:48:17 UTC Sept