aLIGO LHO Logbook

H1 TCS

camilla.compton@LIGO.ORG - posted 21:31, Monday 17 August 2026 - last comment - 12:19, Tuesday 18 August 2026(91567)

Ring heater test on ITMX and ITMY this evening. 2W/segment 4 hours.

TJ, Camilla

I put SR3 into it's O4 alignment (P 458, Y -135) changed from (P 524, Y -135), checked no saturating pixels (ITMX stayed at 1Hz frame rate, ITMY increased to 5Hz), took new HWS references and started the HWS code.

We are running a ring heater test with 2W/segment for 4 hours this evening. Using scripts below on tmux sessions:

python3 /tcs/common/scripts/power_adj_scripts/ring_heater_schedule.py ITMX -s 'now' -d 4 -p 2.0 -ep 0.4
python3 /tcs/common/scripts/power_adj_scripts/ring_heater_schedule.py ITMY -s 'now' -d 4 -p 2.0

Ring heaters should be back to nominal by ~1am. Purpose of this is to check HWS alignment before we align the CO2s (using HWS).

Comments related to this report

camilla.compton@LIGO.ORG - 09:33, Tuesday 18 August 2026 (91580)

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TJ, Camilla ITMY HWS signal looks great. ITMX HWS signal looks noisy, the power on the CCD camera is much smaller than expected, expect this needs realigning after the BS is different.

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camilla.compton@LIGO.ORG - 12:19, Tuesday 18 August 2026 (91586)

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We took the plate of HWS ITMX. With the O4 SR3 alignment, the IX HWS will need realigning, photo attached.

With the new SR3 alignment, we get the HWS beam back but we are clipped, photo, so would probably need to realign either way. This makes sense that this combination of SR3 and BS works together to give a return HWS beam.

Wil not realign until SR3 location is decided, it is easiest for us to realign using ALS.

With new SR3 alignment, ITMY HWS beam power changed ~0.1%.

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