aLIGO LHO Logbook

LHO General - OPS Eve Shift Summary

ibrahim.abouelfettouh@ligo.org — Mon, 15 Sep 2025 22:21:11 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 86954

Literally everyone (to name who I know/can recall would be unfair)

TITLE: 09/16 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: IDLE
INCOMING OPERATOR: NONE
SHIFT SUMMARY:

IFO is in IDLE and DOWN for CORRECTIVE MAINTENANCE buuuuut IFO was OBSERVING for ~1 hr.

Lockloss was intentional in order to avoid potential harmful lockloses and issues throughout the night. We actually got to NLN and OBSERVING though!

It's not exactly over yet - because we have only been locked for 2 hours. Problems may be there and dormant. Nevertheless, we got here from a outrageous outage recovery and a nasty ISC/Lock reacquisition that took 5 days to get back into observing.

The main things:

we don't know our glitch rate yet and omicron is being slow/not showing anything. It's having trouble as confirmed by Jenne and DetChar.
ARM_TRANS is different despite same power output, meaning likely losses elsewhere - this is why we're going IDLE for the night
- X: 1716.84(then) to 1655.87 (now) - Dif = -60.97 % change: 3.7% more pre-outage|| Y: 1530.75 (then) to 1472.84 (now) - Dif = -57.91, % change: 4% more pre-outage

How we got to NLN:

Alog 86951 summarizes the lock acquisition. We just sat there for a bit at OMC_WHITENING as violins fell (and continued to)

After NLN:

Mass acceptance of 127 SDFs (all attached, all accepted)
IMC REFL still stable 3 hrs into MAX POWER
Broadband PCAL run at 2hrs 2hrs 55 mins thermalized (alog 86955)
I killed the lock via the IMC SERVO sign switch

LOG:

None

Images attached to this report

H1 CAL - Post Outage Thermalized NLN BroadBand Calibration

ibrahim.abouelfettouh@ligo.org — Mon, 15 Sep 2025 22:20:37 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 86955

Start Time: 1442034629

End Time: 1442034940

2025-09-15 22:15:22,374 bb measurement complete.
2025-09-15 22:15:22,375 bb output: /ligo/groups/cal/H1/measurements/PCALY2DARM_BB/PCALY2DARM_BB_20250916T051011Z.xml
2025-09-15 22:15:22,375 all measurements complete

CAL

Images attached to this report

H1 PSL - Comment to PSL Inspection After Power Outage

keita.kawabe@ligo.org — Mon, 15 Sep 2025 21:04:49 -0700

Author: keita.kawabe@ligo.org

Report ID: 86952

For PSL table layout, see https://dcc.ligo.org/D1300348/.

Picture 1 and 2: PMC input coupler shows some scattering on the front surface as well as HR surface but nothing unusual. Same thing for the output coupler. (The output coupler clamp plate receives a ghost beam, Jason remembers that this was always the case.)
Picture 3, 4 and 5: HWP (IO-MB-HWP1) and the polarizer for the manual power adjustment, the splitter for EOM-ALS: Not centered but far from clipping.
Picture 6 and 7: EOM input looks a bit off-centered in YAW to the left, but not extraordinarily so. Pictured from different viewing positions to make sure that this is not some kind of photograph artifact.
Picture 8: EOM output. Hard to say anything except that you can see a ghost beam on the EOM case to the right of the output aperture in this picture.
Picture 9: Lenses look OK. Note that you see three spots in L1 but the two are actually EOM output and the ghost beam on the EOM case seen through the lens.
Picture 10: Corner mirror (IO-MB_M3) in front of the motorized HWP rotator.
Picture 11: Motorized HWP rotator. Some scattered light (?) is hitting the mount.
No picture for TFPs, they were very hard to photograph, but the first TFP looked OK when viewed using the IR viewer.
Picture 12 shows the steering mirror below the first TFP that receives the rejected light.
Very hard to picture any scattered light from the periscope mirrors when the power was set to 2W. Which already tells us that there's no scattering/clipping at 1% or even 0.1% level.
Could not take a picture of the PZT mirror, very hard to have a good view of the mirror surface.
Picture 13 and 14: These are between the L2 lens and the corner mirror, IRIS1 is close to L2 and IRIS2 is about a foot downstream. Both look pretty good, if anything the beam might be a bit high on IRIS1.
Picture 15: This is an iris right behind the lens for the bottom periscope mirror transmission (IO_AB_L4). It's off-centered, but Jason thinks that this iris was set a long, long, long time ago and cannot be trusted.
Picture 16: Wincam was placed between the iris pictured above and IO_AB_BS1.
- The distance from the downstream face of the lens holder of IO_AB_L4 and the front of the the attenuator stack was measured to be 76.5mm.
- The Wincam sensor to the front of the stack is known to be 72.3mm.

Images attached to this report

H1 ISC - Locking: Getting LASER_NOISE_SUPPRESSION

ibrahim.abouelfettouh@ligo.org — Mon, 15 Sep 2025 19:29:45 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 86951

Ibrahim, Elenna, Jenne, Ryan S

We made it to LASER_NOISE_SUPPRESSION!

Here's how we got here again and here's what we're monitoring

After much needed help from Ryan S, Elenna and Jenne in initial alignment (manual initial alignment needed), we managed to get back to CARM_5_PICOMETERS but encountered the same issues with an SRM ringup upn getting to RESONANCE, which caused a Lockloss.

Elenna guided me through the following combination of steps tried this morning:

1. Get to CARM_5_PICOMETERS

2. Set TR_CARM_OFFSET to -52

3. Set the REFLAIR_B_RF27 I PRCL matrix to 1.6*(value-it's-at). Press LOAD MATRIX. This is reached by going to LSC->LSC_OVERVIEW->AIR3F (under input matrices area on left of screen, you want to look for REFLAIR_B_RF27 on the left).

4. Continue locking - SRM rang up as before and saturated once but with the new gain, it was enough to not cause a LL.

This worked, and now we're at OMC_WHITENING with high violins (so understandable, sorry fibers).

Now, I'm monitoring H1:IMC-REFL_DC_OUT16 and watching for an increase in power, which is bad. We've been at 63W (the new 60) for 18 minutes - here's a plot of that.

I don't know the calibration, but CDS OVERVIEW is reading out 147MPc

Images attached to this report

H1 CDS - ISC C RF Amp 24M1 power-monitoring beckhoff

erik.vonreis@ligo.org — Mon, 15 Sep 2025 17:49:50 -0700

Author: erik.vonreis@ligo.org

Report ID: 86950

[Fil, Jeff, Dave, Erik, Patrick]

As part of the hunt for problems related to the power outage on September 10, Dave notices that the channel H1:ISC-RF_C_AMP24M1_POWEROK had moved from 1 before the outage to 0 after.

Jeff determined that the output of the amplifier was nominal, so that likely it was a problem with Beckhoff and not with the amplifier itself.

Fil inserted a breakout board between the amp the beckhoff cable and recorded a voltage drop from 3.3 to 2.2 volts on the power ok signal (pin 7).

Some more testing shows the problem was definitely at Beckhoff end. The associated terminal may need to be replaced.

H1 PSL - PSL Inspection After Power Outage

jason.oberling@ligo.org — Mon, 15 Sep 2025 17:07:18 -0700

Author: jason.oberling@ligo.org

Report ID: 86949

J. Oberling, K. Kawabe

This afternoon we went into the PSL enclosure to inspect things after last week's power outage. We concentrated on the IOO side of the PSL table, downstream of the PMC. Our results:

We did a visual inspection with both the IR viewer and the IR-sensitive Nikon camera and did not find any obvious signs of damage on any of the optical surfaces we had access to; the only ones we couldn't see were the crystal surfaces inside the ISC EOM, we could see everything else. I looked at the optics between Amp2 and the PMC and everything there looked normal, no signs of anything amiss.

While the beam was not perfectly centered on every optic, we saw no clipping anywhere in the beam path. The irises after the bottom periscope mirror were not well centered, but they've been that way for a while so we didn't have a good reference for assessing alignment in that path (these irises were set after the O4 PSL upgrade, but there have been a couple of alignment shifts since then and the irises were not reset). For reference, the beam is in the -X direction on the HWP in the power control rotation stage and in the -Z direction (but centered horizontally) on the PZT mirror after the power control stage. We do have a good alignment reference on the ALS path (picked off through mirror IO_MB_M2, the mirror just before the ISC EOM), as those were set as part of the HAM1 realignment during this year's vent. By my eye the first iris looked a tiny bit off in yaw (-Y direction) and pitch (+Z direction), while the second iris looked perfectly centered. We found this odd, so Keita used the IR-sensitive camera to get a better angle on both irises and took some pictures. With the better angle the beam looked well centered in yaw and maybe a little off in pitch (+Z direction) on that first iris, so I think my eye was influenced by the angle from which I was viewing the iris. The second iris still looked very well centered. Edit to add: Since the ALS path alignment looks good, to me this signals that there was not an appreciable alignment shift as a result of the change in PMC temperature. If the PMC was the source of the alignment shift we would see it in both the main IFO and ALS paths. If there is a misalignment in the main IFO path, its source is not the PMC.

The other spot of note is the entrance aperture for the ISC EOM. It's really bright so it's hard to make a definitive determination, but it could be argued there's a very slight misalignment going into the ISC EOM. I couldn't make anything out with the IR viewer, but Keita's picture shows the typical ring around the aperture a little brighter on the left side versus the right. Despite this, there is no clipping in the beam, as we set up a WinCAM beam profiler to check.

The WinCAM was set behind IO_AB_L4, which is the lens immediately behind the bottom periscope mirror (this is the path that goes to the IMC_IN PD). The attached picture shows what the beam looks like there. No signs of clipping in the beam, so it's clearing all the apertures in the beam path. I recall doing a similar measurement at this spot several years ago, but a quick alog search yields nothing. I'll do a deeper dive tomorrow and add a comment should I find anything.

So to summarize, we saw no signs of damage to any visible optical surfaces. We saw no clear evidence of a misalignment in the beam; the ALS path looks good, and nothing in the main IFO path looks suspicious outside of the ISC EOM entrance aperture (a lack of good alignment irises makes this a little difficult to assess; once we get the IFO back to a good alignment we should reset those irises). We saw no clipping in the beam.

Keita has many pictures that he will post as a comment to this log.

OpsInfo

Images attached to this report

LHO General - Ops Day Shift Summary

ryan.short@ligo.org — Mon, 15 Sep 2025 17:07:01 -0700

Author: ryan.short@ligo.org

Report ID: 86945

TITLE: 09/15 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
INCOMING OPERATOR: Ibrahim
SHIFT SUMMARY: More progress today towards recovering H1 back to low noise! We've been able to make it up to LASER_NOISE_SUPPRESSION once so far and updated alignment offsets. Unfortunately we did see the slow increase of IMC REFL again once increasing the input power to 63W during LNS, and shortly after there was an IMC-looking lockloss. Since then, Jason and Keita inspected optics in the PSL and didn't find anything alarming. We attempted to reproduce the IMC REFL behavior with just the IMC locked up to 63W with the ISS secondloop on and off, but did not see it, interestingly. We then decided to try locking again, so an initial alignment with the new green offsets is ongoing.
LOG:

Start Time	System	Name	Location	Lazer_Haz	Task	Time End
15:47	FAC	Nellie	MY	N	Technical cleaning	16:40
16:40	FAC	Kim	MX	N	Technical cleaning	17:31
16:41	FAC	Randy	MY	N		18:25
16:44	ISC	Elenna	LVEA	N	Plugging in freq injection cable	16:49
17:49	FAC	Kim	H2	N	Technical cleaning	18:00
21:15	PEM	TJ	EY	N	Checking DM vacuum pump	22:13
21:16	PSL	Jason, Keita	PSL Encl	Local	Optics inspection	23:11
21:25	VAC	Gerardo	LVEA	N	Check HAM6 pump	21:33
21:37	VAC	Gerardo	MX	N	Inspect insulation	23:12
21:40	CDS	Erik, Fil	LVEA/CER	N	Checking RF chassis	22:13

H1 CDS - third iteration of slow controls channel changes before/after power glitch

david.barker@ligo.org — Mon, 15 Sep 2025 16:32:48 -0700

Author: david.barker@ligo.org

Report ID: 86948

After finding the error code changes for the AMP241M1 sensor, Erik suggested listing channels which have single values before and after, but the value changed.

This table shows a summary of the channel counts, the detailed lists at in attached text files. non-zero to zero is called dead, varying to flatline is called broken, single to diff single is called suspicious.

System	num chans	num_dead	num_broken	num_suspicious
aux-cs	23392	10	10	221
aux-ex	1137	0	0	7
aux-ey	1137	0	0	7
isc-cs	2618	1	0	14
isc-ex	917	0	0	10
isc-ey	917	0	0	9
tcs-cs	1729	1	4	39
tcs-ex	353	0	1	7
tcs-ey	353	0	3	7
sqz-cs	3035	0	4	33

Non-image files attached to this report

H1 PEM - Possible contamination came from dust monitors after power outage

thomas.shaffer@ligo.org — Mon, 15 Sep 2025 16:22:51 -0700

Author: thomas.shaffer@ligo.org

Report ID: 86947

Quick summary - I tested my theory of the dust monitor pump running backwards and spewing contaminate with a pump at EY and was able to get it to run backwards.

A day after the power outage Dave noticed that the PSL dust counts were still very elevated, so I went to check on the corner station dust monitor vacuum pump and found it in an odd state (alog86857). The pump was running very hot, read 0inHg on the dial, and had some loose connections. I turned it off, tightened things up, it turned it back on with good pressure. Thinking more about it after I had walked away, my theory is that the pump started to run backwards when the power went out and the low pressure of the vacuum pulled the pump in reverse. The power then came back on and the motor started and continued in that direction.

Today I wanted to check on the end station pumps, so I took this opportunity to bring a pump that needed to be rebuilt anyway with me to the end station and try to recreate my theory above. I found no pump at EX, so I went to EY where I found the pump completely locked up and the motor, not pump, very hot. I unplugged this, hooked up the one that needed a rebuild and plugged it in. It pulled to -12inHg. I then tried a few times unplugging the power, listening to hear if it started to spin backwards, then pulling it back in. Third time I got it and it was running while pushing a bit of air out of the bleed valve and the pressure read 0inHg.

I didn't test at the dust monitor end of this system if it was spewing out any contaminate, most likely the graphite from the vanes in the pump, but I'd guess if it was running backwards over night it would make enough for us to notice. I'm looking into check valves, in line filters, or some type of relay to avoid this in the future.

LHO General - OPS Eve Shift Start

ibrahim.abouelfettouh@ligo.org — Mon, 15 Sep 2025 16:19:32 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 86946

TITLE: 09/15 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
OUTGOING OPERATOR: Ryan S
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 9mph Gusts, 5mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.09 μm/s
QUICK SUMMARY:

IFO is in IDLE for CORRECTIVE MAINTENANCE

Promise! Today, we were able to get to LASER_NOISE_SUPPRESSION!

Witness to the culprit (In Jenne's words): The IMC_REFL power increases with IMC power increase.

There was a dust monitor that blew back some dust into the PSL that we think may have been the culprit but the Jason and Keita just came back from the PSL after looking for signs of this contamination but found none.

The plan now is to look at the IMC_REFL power increase again by setting the IMC power to 60W then to 63, whilst also trying a new combo:

IMC Power to 60W
ISS 2nd loop ON
ISS 2nd loop OFF
IMC Power to 63W

Did IMC_REFL increase? We shall find out.

H1 ISC - Comment to Green Alignment References Updated

elenna.capote@ligo.org — Mon, 15 Sep 2025 15:57:47 -0700

Author: elenna.capote@ligo.org

Report ID: 86944

I checked the POP A offsets when the alignment converged and updated them.

Images attached to this report

H1 ISC - Comment to Summary of lock attempt

elenna.capote@ligo.org — Mon, 15 Sep 2025 15:20:50 -0700

Author: elenna.capote@ligo.org

Report ID: 86943

It is possible that our sensitivity is back to nominal. Here is a comparison of three lock times, first before the power outage, second during the lock just after the power outage, and third after we turned off ADS today when locked.

These settings were not nominal for the final reference (green on the attached plot):

we had not yet run laser noise suppression (intensity stabilization, adjustments to carm)
no squeezing was injected
we had no OMC whitening engaged
beam diverters were open
not thermalized (blue and orange traces are thermalized)

The low frequency noise is not quite at the level of the "before outage" trace, but it is also not as bad as the orange trace.

Non-image files attached to this report

DARM_noise_compare_power_outage.pdf

H1 General - Comment to Last lockloss from LASER_NOISE_SUPPRESSION was IMC lockloss

oli.patane@ligo.org — Mon, 15 Sep 2025 15:12:25 -0700

Author: oli.patane@ligo.org

Report ID: 86942

Adding a screenshot of what IMC-TRANS looks like along with ASC-AS_{A,B}

Images attached to this report

H1 General - PRM camera at 2W before vs after power outage

oli.patane@ligo.org — Mon, 15 Sep 2025 15:08:41 -0700

Author: oli.patane@ligo.org

Report ID: 86938

Since the power outage, when we've been in the higher 2W locking states, we have been seeing some 'breathing' of a spot in the upper right of the PRM camera. Before the power outage, there was some scattering seen there, but it looked different (now it looks like a thumbprint and has a clear outline when fully there) and didn't 'breathe' like we see now.

Pre-outage (2025-09-09 07:01 UTC) - in PREP_DC_READOUT

Post-outage (2025-09-15 19:44 UTC) - In PREP_DC_READOUT

Images attached to this report

H1 ISC - Summary of lock attempt

elenna.capote@ligo.org — Mon, 15 Sep 2025 14:22:52 -0700

Author: elenna.capote@ligo.org

Report ID: 86940

Following the steps as detailed here: 86935 we were able to get to the engage ASC full IFO state.

I ran the code for engaging IFO ASC by hand, and there were no issues. I did move the alignment around by hand to make sure the buildups were good and the error signals were reasonable. Ryan reset the green references once all the loops, including soft loops engaged.

We held for a bit at 2W DC readout to confer on the plan. We decided to power up and monitor IMC REFL We checked that the IMC REFL power made sense:

we reduce the IMC REFL power by half on IOT2L on Friday
at 2 W, we saw that IMC REFL was 1 mW of power
At 25 W we saw that IMC REFL was 12.7 mW
before the power outage IMC REFL was 8 mW
Daniel reports that the IMC REFL power tripled after the power outage, so we would expect 24 mW
but with the power down by half, we get about 12 mW- this is reasonable
We checked that the power followed this trend as we powered up to full power- 60 W from PSL

I ran guardian code to engage the camera servos so we could see what the low frequency noise looked like. It looked much better than it did the last time we were here!

We then stopped just before laser noise suppression. With IMC REFL down by half, we adjusted many gains up by 6 dB. We determined that on like 5939, where the IMC REFL gain is checked if it is below 2 should now be checked to see if it is below 8. I updated and loaded the guardian.

We rain laser noise suppression with no issues.

Then, I realized that we actually want to increase the power out of the PSL so that the power at IM4 trans matches the value before the power outage- due to the IMC issues that power has dropped from about 56 W to about 54 W.

I opened the ISS second loop with the guardian, and then stepped up PSL requested power from 60 W to 63 W. This seemed to get us the power out we wanted.

Then, while we were sitting at this slightly higher power, we had a lockloss. The lockloss appears to be an IMC lockloss (as in the IMC lost lock before the IFO).

The IMC REFL power had been increasing, which we expected from the increase of the input power. However, it looks like the IMC refl power was increasing even more than it should have been. This doesn't make any sense.

Since we were down, we again took the IMC up to 60 W and then 63 W. We do not see the same IMC refl power increase that we just saw when locked.

I am attaching an ndscope. I used the first time cursor to show when we stepped up to 63 W. You can see that between this first time cursor and second time cursor, the IMC refl power increases and the IM4 trans power drops. However, the iss second loop was NOT on. We also did NOT see this behavior when we stepped up to 60 W during the power up sequence. Finally, we could not replicate this behavior when we held in down and increased the input power with the IMC locked.

Images attached to this report

H1 ISC - Green Alignment References Updated

ryan.short@ligo.org — Mon, 15 Sep 2025 14:22:30 -0700

Author: ryan.short@ligo.org

Report ID: 86941

After engaging full IFO ASC and soft loops this afternoon, I updated the ITM camera and ALS QPD offsets and accepted them in the appropriate SAFE SDF tables. After Beckhoff reboots and PSL optic inspections, we'll run an initial alignment to solidify these alignment setpoints. They will need to be accepted in the OBSERVE tables once eventually back to NLN.

OpsInfo

Images attached to this report

H1 General - Last lockloss from LASER_NOISE_SUPPRESSION was IMC lockloss

oli.patane@ligo.org — Mon, 15 Sep 2025 14:11:00 -0700

Author: oli.patane@ligo.org

Report ID: 86939

We had a lockloss while in LASER_NOISE_SUPPRESSION (575), and looking at ASC-AS_A, the light on the PD dropped at the same time as DARM lost lock, so it was an IMC lockloss (lockloss webpage is still unaccessible but command line tool worked for me after waiting a while)

ISC, Lockloss

Images attached to this report

H1 CDS - Slow controls channels which were varying before glitch and flat-lined after

david.barker@ligo.org — Mon, 15 Sep 2025 13:41:22 -0700

Author: david.barker@ligo.org

Report ID: 86937

The previous channel list was channels which were non-zero before the glitch and became zero afterwards.

I've extended the analysis to look for channels which were varying before the glitch and became flat-lined afterwards, the flat-line value is shown.

auxcs.txt: H1:SYS-ETHERCAT_AUXCORNER_INFO_CB_QUEUE_2_PERCENT (varying→flat:8.000e-05)
auxcs.txt: H1:SYS-TIMING_C_FO_A_PORT_12_NODE_GENERIC_PAYLOAD_1 (varying→flat:9.100e+06)
auxcs.txt: H1:SYS-TIMING_C_FO_A_PORT_12_NODE_XOLOCK_MEASUREDFREQ (varying→flat:9.100e+06)
auxcs.txt: H1:SYS-TIMING_C_FO_B_PORT_11_NODE_GENERIC_PAYLOAD_0 (varying→flat:1.679e+04)
auxcs.txt: H1:SYS-TIMING_C_FO_B_PORT_11_NODE_GENERIC_PAYLOAD_17 (varying→flat:2.620e+02)
auxcs.txt: H1:SYS-TIMING_C_FO_B_PORT_11_NODE_PCIE_HASEXTPPS (varying→flat:1.000e+00)
auxcs.txt: H1:SYS-TIMING_C_FO_B_PORT_2_NODE_GENERIC_PAYLOAD_13 (varying→flat:5.830e+02)
auxcs.txt: H1:SYS-TIMING_C_FO_B_PORT_3_NODE_GENERIC_PAYLOAD_13 (varying→flat:6.470e+02)
auxcs.txt: H1:SYS-TIMING_X_GPS_A_DOP (varying→flat:3.000e-01)
auxcs.txt: H1:SYS-TIMING_Y_GPS_A_DOP (varying→flat:3.000e-01)
sqzcs.txt: H1:SQZ-FIBR_LOCK_BEAT_FREQUENCYERROR (varying→flat:2.000e+00)
sqzcs.txt: H1:SQZ-FREQ_ADF (varying→flat:-3.200e+02)
sqzcs.txt: H1:SQZ-FREQ_LASERBEATVSDOUBLELASERVCO (varying→flat:2.000e+00)
sqzcs.txt: H1:SYS-ETHERCAT_SQZCORNER_CPUUSAGE (varying→flat:1.200e+01)
tcsex.txt: H1:SYS-ETHERCAT_TCSENDX_CPUUSAGE (varying→flat:1.200e+01)
tcsey.txt: H1:AOS-ETMY_BAFFLEPD_4_ERROR_CODE (varying→flat:6.400e+01)
tcsey.txt: H1:AOS-ETMY_BAFFLEPD_4_ERROR_FLAG (varying→flat:1.000e+00)
tcsey.txt: H1:AOS-ETMY_ERROR_CODE (varying→flat:1.000e+01)

H1 ISC - IM4 Trans at 2W in, Before Outage comapred to Now

camilla.compton@ligo.org — Mon, 15 Sep 2025 12:20:50 -0700

Author: camilla.compton@ligo.org

Report ID: 86936

Comparing IM4 Trans alignment at 2W in before the power outage to now. Plot attached.

IM4 trans Pitch alignment is the same, Yaw alignment is 0.06 different. So alignment changes are minimal.

Power on IM4 trans is slightly (~3%) lower: NSUM Power on IM4 trans was 1.891 for 2.026W in (ratio 0.933), now is 1.780 for 1.974 in (ratio 0.902).

Images attached to this report

H1 ISC - Recipe for arms on resonance

elenna.capote@ligo.org — Mon, 15 Sep 2025 12:04:47 -0700

Author: elenna.capote@ligo.org

Report ID: 86935

Here are the steps Sheila and I took that almost got us to prep ASC for full ifo:

take guardian to carm_5_picometers
change H1:LSC-TR_CARM_OFFSET to -52
ramp H1:LSC-TR_CARM_GAIN to 2.1
change H1:LSC-TR_CARM_OFFSET to -56

We measured all the LSC gains and found that maybe PRCL gain was dropping and causing locklosses so

increase PRCL2 gain from 1 to 1.6
increase DHARD P gain to -30, DHARD Y gain to -40
run CARM_TO_REFL state in guardian
reduce H1:LSC-TR_REFLAIR9_OFFSET (make sure to set a ramp time first!) slowly to zero
ran RESONANCE state in guardian
ran CARM_TO_ANALOG

We then went to prep_ASC_for_Full_ifo but we forgot to reduce the PRCL2 gain, so this probably caused a lockloss since DRMI moved to POP

We will keep trying this and maybe do full IFO ASC next

On the next attempt, I added this additional step:

before DRMI to POP, I realized that I should drop the PRCL2 gain
by hand, I lowered the PRCL2 gain slightly, and then increased the input matrix value for REFLAIR27 I accordingly until that was 1.6 times higher than its nominal value
then, I ran DRMI to POP, which went fine.

H1 AOS - DQ Shift Report: LHO 08 Sept- 14 Sept 2025

mirandarose.claypool@ligo.org — Mon, 15 Sep 2025 11:50:21 -0700

Author: mirandarose.claypool@ligo.org

Report ID: 86931

Hi y'all!

Link to full report here.

Summary:

73%, 44.6%, 71.8%, 43.02%, 0%, 0%, 0% Observing per day
Large EQ off coast of OR, as well as an electrical storm, caused lockloss/glitches on Tues
Power outage on Wednesday caused many issues with IFO
Greatly reduced range on Thursday, as well as extremely increased glitchrate
IFO down for corrective maintenance from Thursday onwards.
One HVeto repeated winner for Mon, Tues, Wed:H1:LSC-REFL_A_LF_OUT_DQ. On Thursday, following the power outage, there were 12 round winners, 9 of which belonged to IMC
Only three days of FScan-Observing: Mon - Wed. Tuesday was the lowest and Wednesday was the highest. All three hovered around ~2500 lines

DetChar

H1 CDS - Comment to Program to detect channel issues following power glitch

david.barker@ligo.org — Mon, 15 Sep 2025 11:47:28 -0700

Author: david.barker@ligo.org

Report ID: 86934

ini_file: H1EPICS_ECATTCSEX

num_chans: 353

dead_chans: 0

ini_file: H1EPICS_ECATTCSEY

num_chans: 353

dead_chans: 0

ini_file: H1EPICS_ECATSQZCS

num_chans: 3035

dead_chans: 0

H1 CDS - Comment to Program to detect channel issues following power glitch

david.barker@ligo.org — Mon, 15 Sep 2025 11:40:11 -0700

Author: david.barker@ligo.org

Report ID: 86933

ini_file: H1EPICS_ECATTCSCS

num_chans: 1729

dead_chans: 1

H1:TCS-ITMY_CO2_LASERPOWER_RS_ENC_INPUTA_STATUS

H1 CDS - Comment to Program to detect channel issues following power glitch

david.barker@ligo.org — Mon, 15 Sep 2025 11:39:06 -0700

Author: david.barker@ligo.org

Report ID: 86932

ini_file: H1EPICS_ECATISCEX

num_chans: 917

dead_chans: 0

ini_file: H1EPICS_ECATISCEY

num_chans: 917

dead_chans: 0

H1 CDS - Comment to Program to detect channel issues following power glitch

david.barker@ligo.org — Mon, 15 Sep 2025 11:24:11 -0700

Author: david.barker@ligo.org

Report ID: 86930

ini_file: H1EPICS_ECATISCCS

num_chans: 2618

num_dead: 1

H1:ISC-RF_C_AMP24M1_POWEROK

H1 CDS - Comment to Program to detect channel issues following power glitch

david.barker@ligo.org — Mon, 15 Sep 2025 11:23:16 -0700

Author: david.barker@ligo.org

Report ID: 86929

ini_file: H1EPICS_ECATAUXEX

num_chans: 1137

dead_chans: 0

ini_file: H1EPICS_ECATAUXEY

num_chans: 1137

dead_chans: 0

LHO VE - Mon CP1 Fill

david.barker@ligo.org — Mon, 15 Sep 2025 11:08:28 -0700

Author: david.barker@ligo.org

Report ID: 86928

Mon Sep 15 10:07:58 2025 INFO: Fill completed in 7min 54secs

Images attached to this report

H1 DetChar - Comment to Detchar request- help understanding our IMC-related glitches.

elenna.capote@ligo.org — Mon, 15 Sep 2025 10:20:14 -0700

Author: elenna.capote@ligo.org

Report ID: 86927

To add to this investigation:

We attenuated the power on IMC refl, as reported in alog 86884. We have not gone back to 60 W since, but it would be interesting to know if a) there was glitches in the IMC channels at 2W before the attenuation, and b) if there were glitches at 2 W after the attenuation. We can also take the input power to 60 W without locking to check if the glitches are still present.

H1 CDS - Comment to Program to detect channel issues following power glitch

david.barker@ligo.org — Mon, 15 Sep 2025 10:08:01 -0700

Author: david.barker@ligo.org

Report ID: 86926

ini file: H1EPICS_ECATAUXCS.ini

num_chans: 23392

dead chans: 10

H1:PSL-ENV_LASERRMTOANTERM_DPRESS
H1:SYS-ETHERCAT_AUXCORNER_INFO_CB_QUEUE_2_USED
H1:SYS-PROTECTION_AS_TESTNEEDED
H1:SYS-PROTECTION_AS_TESTOUTDATED
H1:SYS-TIMING_C_FO_A_PORT_13_CRCERRCOUNT
H1:SYS-TIMING_C_MA_A_PORT_14_NODE_UPLINKCRCERRCOUNT
H1:SYS-TIMING_C_MA_A_PORT_8_NODE_FANOUT_DELAYERR
H1:SYS-TIMING_X_FO_A_UPLINKCRCERRCOUNT
H1:SYS-TIMING_Y_FO_A_PORT_6_CRCERRCOUNT
H1:SYS-TIMING_Y_FO_A_PORT_6_NODE_PCIE_OCXOLOCKED

H1 CDS - Program to detect channel issues following power glitch

david.barker@ligo.org — Mon, 15 Sep 2025 10:05:42 -0700

Author: david.barker@ligo.org

Report ID: 86925

I** have written a program to compare slow controls channels before and after with Wed 10sep2025 power glitch to see if there are any which look like they may have been broken and need further investigation.

(** Full disclosure, it was actually written by AI (Claude-code) and runs on my GC laptop safely contained in a virtual machine running Deb13 Trixie)

As a first pass, the code is looking for dead channels. These are channels which were active before the glitch, and are flat-line zero following.

The code gets its channels to analyze from the slow controls INI files.

Using Jonathan's simple_frames python module, it reads two minute trend GWF frame files. For before I'm using the 10:00-11:00 Wednesday file (an hour before the glitch) and for after I'm using the Thu 00:00-01:00 file. In both cases H1 was locked.

I'll post the results as comments to this alog.

LHO General - Comment to Ops Day Shift Start

camilla.compton@ligo.org — Mon, 15 Sep 2025 09:48:14 -0700

Author: camilla.compton@ligo.org

Report ID: 86924

Plot attached of the lockloss, Elenna pointed out we need to look at the faster channels. The oscillation started once the REFLAIR9 offset was -0.02 and higher. It's a 17Hz to 18Hz woble, also seen growing in all the LSC signals, which makes more sense for the fast frequency.

This same 17Hz LSC wobble was seen in the last lockloss last night too, plot.

Images attached to this report

LHO General - Comment to Ops Day Shift Start

sheila.dwyer@ligo.org — Mon, 15 Sep 2025 09:05:45 -0700

Author: sheila.dwyer@ligo.org

Report ID: 86923

Attempt 1:

CARM_5_pm by guardian. TR_CARM offset -52, could then set TR_CARM gain to 2.1, then could step TR_CARM offset to -56. Then could set DHARD P gain to -30 and DHARD Y gain to -40.

Then ran CARM_TO_TR with the guardian. We could step the TR_REFLAIR9 offset to -0.03 and things looked stable, things started to ring up at 2Hz when we stepped to -0.02.

It seems like the increased DAHRD gain helped keep things more stable than last night.

LHO General - Comment to OPS Eve Shift Summary

sheila.dwyer@ligo.org — Mon, 15 Sep 2025 08:25:50 -0700

Author: sheila.dwyer@ligo.org

Report ID: 86922

Here are two screenshots to show our last attempt last night.

Second one show the TR_REFL 9 erorr signal as we stepped the TR_CARM offset closer to resonance. There is some noise in the TR_REFL9 signal, due to alignment fluctuations coupling when we are not on resonance. As we get closer to resonance by increasing the TR_CARM gain as the optical gain of the side of fringe signal drops, the refl signal gets a little quieter. The offset gets set to zero the error signal right before the handoff, and as you can see the handoff to the error signal works well and the refl 9 signal become quiet once it is in loop. Looking at the TR_CARM signal after the handoff, you can see that the arm powers fluctate because they are now seeing the noise from refl 9 which is now in loop.

When the offset is removed, TR_CARM goes to about 58. All build ups become wobbly when the offset is removed to go to resonance. This means that something seems wrong with the TR REFLAIR9 error signal, which could be due to an alignment problem or an issue with the sensor itself.

Images attached to this report

LHO General - Ops Day Shift Start

ryan.short@ligo.org — Mon, 15 Sep 2025 07:40:40 -0700

Author: ryan.short@ligo.org

Report ID: 86921

TITLE: 09/15 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 6mph Gusts, 3mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.09 μm/s
QUICK SUMMARY: I'll start by taking H1 through an initial alignment then relock up through CARM_5_PICOMETERS, since it sounds like that's still the latest stable state H1 can get to.

LHO General - OPS Eve Shift Summary

ibrahim.abouelfettouh@ligo.org — Sun, 14 Sep 2025 22:15:43 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 86920

TITLE: 09/15 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
INCOMING OPERATOR: None
SHIFT SUMMARY:

IFO is in IDLE for CORRECTIVE MAINTENANCE

The mission today was to get to RESONANCE. We got really close!

The idea was that the calculated TR_CARM offset was likey incorrect so we had to step the offset to maintain stability as we went into resonance. So attempts below are all from CARM_TO_5_PICOMETERS.

While sitting in CARM_TO_REFL during handoff, took RF_DARM TF (attached).

I'm stealing Ryan S's format for his IFO troubleshooting today since it was so easy to read! (Thanks Ryan!)

Reference for healthy CARM to RESONANCE transition pre-outage: 2025/09/09 20:01 UTC, GPS: 1441483301

Relocked,

TR_CARM_OFFSET set -52
Lockloss ~2-3s into CARM_TO_REFL
Could be a 5.3 EQ but unlikely

Relocked,

TR_CARM_OFFSET set -52
Lockloss ~2-3s into CARM_TO_REFL
Alignment looked bad judging from INP1_INMON, buildups and AS_AIR so touched PRM to make better, which worked.
Lockloss at 10s after CARM_TO_REFL, but the state finished
Conclusion: alignment was still bad and more touching didn't help

Ran Initial Alignment - fully auto

Relocked,

TR_CARM_OFFSET to -52
CARM_TO_REFL Successful
Sheila's advice was to step slowly into RESONANCE with the first line of code and see what happens, which I did
SRM Saturated at 02:21:18 UTC (attached)
Lockloss at 02:21:20 (DRMI)
Looked at OPLEVS but no indication that they saw anything (attached)

Relocked,

Took DHARD_P SS 2W OLG TF per Shela's instruction - no indication and the measurement didn't really look good due to low coherence. Phase was ok.
Sheila came online
TR_CARM_OFFSET to -52
CARM_TO_REFL reached but PRG unstable
Lockloss ~3s after

Plan now was to try to step the TR_CARM_GAIN up as we were stepping the TR_CARM_OFFSET down further from -52 to keep the UGF consistent and not cause a LL. Sheila plannd to measure this each time we stepped it.

Relocked,

TR_CARM_OFFSET to -52, UGF measured, TR_CARM_GAIN to 1.2 (from 1)
TR_CARM_OFFSET to -53, UGF measured, TR_CARM_GAIN to 1.4
TR_CARM_OFFSET to -54, UGF measured, TR_CARM_GAIN to 1.7
TR_CARM_OFFSET to -56, UGF measured, TR_CARM_GAIN to 2.1
Sheila stepped into resonance by trying to split up the offset reduction (1st line of RESONANCE) but this failed either due to the problem or because there was 0 ramp time
Lockloss

IFO in IDLE per Sheila's Instruction. We will try again tomorrow.

LOG:

None

Images attached to this report

LHO General - Ops Day Shift Summary

ryan.short@ligo.org — Sun, 14 Sep 2025 17:10:32 -0700

Author: ryan.short@ligo.org

Report ID: 86919

TITLE: 09/14 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
INCOMING OPERATOR: Ibrahim
SHIFT SUMMARY: More troubleshooting today on H1 locking, primarily focused on getting through the CARM_TO_REFL transition and RESONANCE states. See my morning alog for details on the first half of the day; the rest I list here:

After a discussion online between people, decided using a different TR CARM offset may be the path forward
Reverted my earlier change of LSC_TR_REFLAIR9_CARM_TO_REF gain in lscparams back to -0.8
Relocked - held in CARM_5_PICOMETERS and stepped TR_CARM offset
- Took TR CARM transfer function between steps to check UGF doesn't get too low
- Settled on -52 as a good offset
- Moved to CARM_TO_ANALOG, PRG got noisy, waited here about 10 sec
- Moved to RESONANCE, PRG less noisy, but DHARD control signals got glitchy and lockloss
- 2 Hz ringup seen in DHARD and DARM
Relocked - after CARM_5_PICOMETERS lowered TR CARM offset to -52
- Requested CARM_TO_ANALOG, lockloss soon after entering RESONANCE
Relocked - lowered TR CARM offset again after CARM_5_PICOMETERS
- Turned off DHARD loops
- Requested CARM_TO_ANALOG; lockloss at same place in RESONANCE
- Realized RESONANCE turns DHARD gains back on, temporarily commented these lines out for next attempt
Relocked - did NOT lower TR CARM gain
- Turned off DHARD loops
- Requested RESONANCE, lockloss at same place
Relocked - lowered TR CARM offset again after CARM_5_PICOMETERS
- Turned off DHARD loops
- Requested RESONANCE, lockloss at same place
Relocked - lowered TR CARM offset even lower to -55
- Left DHARD on
- Lockloss before even leaving CARM_5_PICOMETERS
- -55 is too low of an offset
Relocked - lowered TR CARM offset to -52
- Left DHARD on
- Lockloss at start of RESONANCE again
Relocked - lowered TR CARM offset to -52
- Uncommented DHARD gains in RESONANCE
- Moved to CARM_TO_ANALOG, PRG noisy but otherwise stable
- Ibrahim starts taking measurements

Generally locking has been very easy today up through CARM_5_PICOMETERS and alignment has been good.

LHO General - OPS Eve Shift Start

ibrahim.abouelfettouh@ligo.org — Sun, 14 Sep 2025 16:12:31 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 86918

TITLE: 09/14 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
OUTGOING OPERATOR: Ryan S
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 10mph Gusts, 6mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.12 μm/s
QUICK SUMMARY:

IFO is DOWN for CORRECTIVE MAINTENANCE

Ryan S has tried an exhaustive combination (I will link the alog when posted) of lock attempts to get beyond where we were yesterday, which was losing lock upon loading the matrix necessary to get from CARM_5_PICOMETERS to CARM_TO_REFL to RESONANCE.

I don't have any ideas of what to try but will be in communication with comissioners.

H1 General - Summary of Morning Locking Attempts

ryan.short@ligo.org — Sun, 14 Sep 2025 11:48:56 -0700

Author: ryan.short@ligo.org

Report ID: 86917

Below is my outline of locking attempts so far this morning, with any changes I made in Guardian or otherwise in bold:

Plan to start w/ initial alignment then allow ISC_LOCK to go up to 'RESONANCE' if possible
- Sheila messages saying CARM_TO_ANALOG won't work; changed ISC_LOCK line 2826 from 2 to 8
Alignment goes without issue, just needed some SRM adjustment
Lockloss early in 'RESONANCE', maybe actually something at end of CARM_TO_REFL like Ibrahim found last night
- DHARD control signals got very glitchy
Relocked - lockloss while waiting in CARM_TO_REFL after it finished; definitely end of this state (matrix loading?) is the issue
While relocking, lockloss in DHARD_WFS, seems like alignment was just bad
- Added SRC loops back into DRMI ASC since they should work after Elenna's dark offset updates
- They do
Relocked - holding in CARM_5_PICOMETERS while stepping CHARD P and Y to try and increase LSC-REFL
- Not seeing much appreciable improvement
- Reverted Sheila's REFLAIR phase changes from yesterday
- Tried CARM_TO_REFL again; lockloss
- SDF_REVERT reverts my phase reversion
Relocked - held in CARM_5_PIVOMETERS to measure TR CARM transfer function
- Gain looks too high compared to Feb 2023 reference (screenshot 1), changed LSC_TR_REFLAIR9_CARM_TO_REF gain in lscparams from -0.8 to -0.46 (might undo this later)
- Remeasured (screenshot 2)
- Tried CARM_TO_REFL again with new gain; lockloss

Images attached to this report

H1 ISC - summary of recent changes

sheila.dwyer@ligo.org — Sun, 14 Sep 2025 11:26:50 -0700

Author: sheila.dwyer@ligo.org

Report ID: 86916

Summary of what we've changed so far since the overnight lock where IMC visibility degraded: (strting some notes, plan to add links later).

reduced power on IMC refl diode
rephased REFLAIR 9 + 45 for DRMI acquisition
dark offsets for AS_C and AS 72, this makes DRMI ASC work again
reduced tr_REFLAIR gain to match a reference from 2023, this did not help us make it through that transition, might be something we want to undo.

LHO VE - Sun CP1 Fill

david.barker@ligo.org — Sun, 14 Sep 2025 10:36:35 -0700

Author: david.barker@ligo.org

Report ID: 86915

Sun Sep 14 10:08:17 2025 INFO: Fill completed in 8min 14secs

Images attached to this report

LHO General - Ops Day Shift Start

ryan.short@ligo.org — Sun, 14 Sep 2025 07:47:31 -0700

Author: ryan.short@ligo.org

Report ID: 86914

TITLE: 09/14 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 30mph Gusts, 24mph 3min avg
    Primary useism: 0.04 μm/s
    Secondary useism: 0.11 μm/s
QUICK SUMMARY: Windy and rainy morning on-site. I'll start by running H1 through a fresh initial alignment, then continue troubleshooting where Ibrahim left off last night.

LHO General - OPS Eve Shift Summary

ibrahim.abouelfettouh@ligo.org — Sat, 13 Sep 2025 21:01:56 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 86913

TITLE: 09/14 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
INCOMING OPERATOR: None
SHIFT SUMMARY:

IFO is in IDLE and CORRECTIVE MAINTENANCE

The "good" news:

DHARD P loop has been successfully automatic since closing it this afternoon. We can lock all the way to CARM_5_PICOMETERS quite quickly. DRMI has also been good to me this evening.

The bad news:

We thought we were losing lock at RESONANCE, but we were really losing lock at CARM_5_PICOMETERS.

Stepping through this state has showed that its only at the end of this, where the matrix involving REFL_BIAS, TR_REFL9 and TR_CARM is loaded, we lose lock roughly 10s later due to SRM becoming unstable quickly.

I investigated this via alogs 86909, 86910, 86911, 86912, which are comments to my OPS shift start (alog 86908). After being led down a rabbit hole of ramp times, from 3 other times where that was the problem, I can confirm that this isn't it. Curiously, lock was lost faster with a longer ramp time.

With confirmation from TJ and Jenne, I'm leaving IFO in IDLE with the plan being to solve this problem in tomorrow's shift.

I do feel like we're close to solving this problem or at least figuring out where the issue lies. Specific details are in the alogs listed below.

LOG:

None

LHO General - Comment to OPS Eve Shift Start

ibrahim.abouelfettouh@ligo.org — Sat, 13 Sep 2025 20:27:22 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 86912

I found an alog from Craig about REFLAIR9 (alog 43784). I'm somewhat more convinced that something involving the REFLAIR9_OFFSET and POP_LF?

The line from the alog: "we have made it through this transition every time now, but the PR_GAIN number on the striptool still spikes, meaning the POP_LF power changes rapidly through this transition, which is probably bad." sounds relevant?

I'm still confused why the REFLAIR9_OFFSET turning on causes an instability in PR_GAIN, which causes an instability in SRM which causes a lockloss.

I'm sufficiently confused at this stage so will attempt to go through the usual lockloss again to see if it's the same. Then I'll try stepping through again as a sanity check.

So far, I've only changed ramp times, immediately changing them back.

~~One thing that's confusing me is what the "REFL_BIAS" means. The REFL_BIAS Gain is 86 but the REFL_BIAS value in ISC_Library is 9.~~ Nevermind, I think one refers to the location within a matrix in terms of the element number whereas the other is the value of that number within the matrix.

LHO General - Comment to OPS Eve Shift Start

ibrahim.abouelfettouh@ligo.org — Sat, 13 Sep 2025 19:08:09 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 86911

As expected, that did not fix it, rather it seemed as though the faster ramp time caused a weird offset in REFLAIR9, which didn't happen last time. I checked the log and confirmed that there was a 4s instead of 2s ramp time but I'm kind of struggling to see it (attached).

There seems to be a 25hz signal on POP_A as soon as I increased the ramp time. Additionally, there wasn't really an instability upon turning on CARM_TO_REFL. It was stable for 9s until LL, showing a kick 3s before rather than a degradation. Additionally, the lockloss wasn't as violent.

With the tiniest font, maybe an even longer ramp time would work? Very unconvincing.

I don't have many ideas right now, but I'm reading the alog, the wiki and then devising some plan based off an idea of how this part of lock works.

LHO General - Comment to OPS Eve Shift Start

ibrahim.abouelfettouh@ligo.org — Sat, 13 Sep 2025 18:29:21 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 86910

In looking at the problem lines loaded by the matrix, I see REFL_BIAS, TR_REFL9 and TR_CARM.

According to ISC_library.py, these are REFL_BIAS=9, TR_REFL9 = 27 and TR_CARM = 26. I don't know what this means yet.

Then, I looked at alogs hoping to find the last time something like this happened, which from vague memory was during post-vent recovery this year (with Craig and Georgia):

Looking for REFL_BIAS, I found Sheila's 2018 alog 43623 talking about the TR_CARM transition and how SRM would saturate first, which was what I was experiencing. Specifically the line is: TR_CARM transition: This has been unreliable for the last several days, our most frequent reason for failure in locking. We found that the problem was a large transient when the REFL_BIAS (TR CARM) path is first engaged would saturate SRM M1. We looked at the old version of the guardian and found that this used to be ramped on over 2 seconds, but has been ramped over 0.1 seconds recently. This transition has been sucsesfull both of the times we tried it since changing the ramp time, in one try there was no transient and in the other there was a transient but we stayed locked.

Looking for TR_REFL9, I found Craig's alog 84679 from the aforementioned post-vent recovery. Same issue with ramp time too, specifically referencing the few lines of ISC_LOCK that I posted above. He moved the ramp time to 2s, which I confirmed is still there. He has a picture of the lockloss (attached below) and it looks very similar to the ones we have been having. I trended the same channels he did and found that after this 2s ramp time, PR_GAIN would become unstable after 10s (attached below). Also found Elenna's alog (where I was also on-shift) dealing with the same issue, but before Craig had increased the ramp time - alog 84569. The deja vu was real. Buut I'm unsure this is the same issue because the ramp time is indeed 2s.

Looking for TR_CARM, I found this recent alog from Elenna discussing CARM, REFL and DHARD WFs - unknown whether it is relevant. Alog 86469. I will read this more closely.

While the I'm being led to just increase the ramp time further, I truly doubt this will change much since 2s is quite large of a ramp time and doesn't really explain much. Given all that, I'm going to try it before looking further since we've gotten back here in the time it took to write and investigate this.

Images attached to this report

LHO General - Comment to OPS Eve Shift Start

ibrahim.abouelfettouh@ligo.org — Sat, 13 Sep 2025 17:10:03 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 86909

Writing this before I attempt to look at ISC_library but:

Our last stable state took us to CARM_5_PICOMETERS. I stayed there just to be sure it was stable.

I then followed the procedure and stepped through the next state, CARM_TO_REFL.

Line 2701-2710 contain both an ezca and a self. state so couldn't run that if loop's ezca states - may contact someone about this but the lines were:

if self.NN < 20:

self.myoffset = self.myoffset + ezca['LSC-TR_REFLAIR9_INMON']

self.timer['wait'] = 0.2

self.NN += 1

else:

self.myoffset = self.myoffset / self.NN

ezca['LSC-TR_REFLAIR9_OFFSET'] = round(-1*self.myoffset,3)

self.counter += 1

I continued stepping through
On the last line, which was "ISC_library.intrix['REFLBIAS', 'TR_REFL9'] = 2.0", the same 35hz ringup occured, causing a lockloss.

I will begin investigating what I can but I think this an issue with loading the matrix from ISC_Library, implying something is up with REFLBIAS or TR_REFL9? Somewhat out of my depth but will investigate alogs, wiki, ISC_library and anything else I can.

Either way, it seems that we thought we were losing at RESONANCE but it was the CARM_TO_REFL's last line, unless I got something wrong in the if-loop I didn't run through, which is also something I will investigate.

LHO General - OPS Eve Shift Start

ibrahim.abouelfettouh@ligo.org — Sat, 13 Sep 2025 16:39:38 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 86908

TITLE: 09/13 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
OUTGOING OPERATOR: Ryan S
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 17mph Gusts, 11mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.15 μm/s
QUICK SUMMARY:

IFO is DOWN in CORRECTIVE MAINTENANCE

There was a lot of good work done today. Primarily rephasing REFLAIR (alog 86903) and closing DHARD_P loop. This has allowed us to easily get past DRMI. It seems that we are still losing lock around resonance due to a 35hz fast ringup.

The Procedure for the EVE:

Try DHARD_WFS and step to resonance (state before lockloss). If DHARD_WFS doesn't woprk,
1. comment out line 2430, 2404 of ISC_LOCK.py
2. Then go to CARM_5_PICOMETERS and turn DHARD_P Gain to -1, then -10. This is slow
If DHARD_WFS works, keep going and step through states by:
1. once at previous state of the one you want to step
2. "guardian -i ISC_LOCK"
  1. Copy the ezca lines
  2. copt intrix load lines
  3. do NOT copy "self.lines" or the library - that's done by the guardian -i
3. Copy line by line and see it work. If state is done, MANUAL to state AFTER desired state

What has happened so far:

Same PR_G ringup caused lockloss at RESONANCE and CARM_TO_REFL so I'm going to the state before, which is CARM_5_PICOMETERS. Will follow the blueprint above. Thankfully DHARD_P worked 2x now.

H1 ISC - Comment to rephasing REFLAIR (PRMI and DRMI locking diode), further locking progress

sheila.dwyer@ligo.org — Sat, 13 Sep 2025 16:00:44 -0700

Author: sheila.dwyer@ligo.org

Report ID: 86907

Elenna, Ibrahim, Ryan, Sheila

We had one more attempt at locking, we were able to close DHARD Y wfs with the guardian, and we stepped DHARD P as we stepped up the CARM offset. Elenna fixed up DRMI along the way as well.

We engaged the DHARD P loop with the usual sign and gain when the TR_CARM offset was -35. Then we let the guardian continue, and lost lock in the CARM_TO_ANALOG state.

Ibrahim has a few plans of what to try next.

LHO General - Ops Day Shift Summary

ryan.short@ligo.org — Sat, 13 Sep 2025 14:36:17 -0700

Author: ryan.short@ligo.org

Report ID: 86906

TITLE: 09/13 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
INCOMING OPERATOR: Ibrahim
SHIFT SUMMARY: The main efforts of today have been trying to get past DHARD_WFS. DRMI is now less troublesome since Sheila and Elenna rephased REFLAIR and some dark offsets were updated, and we are able to make it up to DARM_TO_RF consistently without intervention other than an occasional SRM alignment touchup. See the rephasing alog comments for details on locking efforts this afternoon.
LOG:

Start Time	System	Name	Location	Lazer_Haz	Task	Time End
18:39	CDS	Richard	CER	N	Checking RF	18:46

H1 ISC - Comment to rephasing REFLAIR (PRMI and DRMI locking diode), further locking progress

ryan.short@ligo.org — Sat, 13 Sep 2025 14:35:42 -0700

Author: ryan.short@ligo.org

Report ID: 86905

I have made three more attempts through DHARD_WFS, both unsuccessful. Each time, once in DARM_TO_RF, I've manually engaged DHARD_Y's initial gain, watched the error signal converge, then increased to the final gain without issue. I then would engage DHARD_P's initial gain with the opposite sign and watch the error signal slowly converge after many minutes. Both times, whenever I would increase the DHARD_P gain, soon after the control signal would start moving away from zero (away from the direction it came) and there would be a lockloss.

On the thrid attempt I did the same as before, but this time stepped the CARM offset from -3 to -5 before engaging DHARD_P, but ultimately this attempt didn't work either. I noticed that once the DHARD_P error signal crosses zero, DHARD_Y starts running away (?). If I'm fast enough, I can turn the gains to zero before a lockloss happens, then bring the buildups back up by adjusting PRM. This juggling act of turning the DHARD loops on and off while adjusting PRM went on for a while, but inevitably ended in a lockloss.

H1 ISC - SRC Dark Offsets Updated

ryan.short@ligo.org — Sat, 13 Sep 2025 12:45:28 -0700

Author: ryan.short@ligo.org

Report ID: 86902

E. Capote, R. Short

While locking DRMI sevral times this morning, I had noticed the SRC loops are what have been pulling alignment away once DRMI ASC engages. I have put INP1, PRC1, and PRC2 back into Guardian to be turned on during DRMI ASC, and so far they have been working well. Elenna looked into this and noticed the dark offsets for sensors used for SRC needed to be updated, so she did so and the accepted SDFs are attached (all changes in the screenshot were accepted except for the last two in the list related to RF36).

OpsInfo

Images attached to this report

H1 ISC - Comment to rephasing REFLAIR (PRMI and DRMI locking diode), further locking progress

sheila.dwyer@ligo.org — Sat, 13 Sep 2025 12:42:38 -0700

Author: sheila.dwyer@ligo.org

Report ID: 86904

We made two attempts to close the DHAD WFS. In the first, we stepped the TR_CARM offset to -7 and tried the guardian steps. Looking at the lockloss it looked like the sign of both DHARD loops was wrong and pulling us to a bad alignment.

In the second attempt, we stayed at the TR_CARM offset of -3 (from DARM_TO_RF), and tried manually to engage them. The yaw loop was fine and we were able to use the normal full gain. For the pitch loop, it did seem to have the wrong sign so we tried flipping the sign. The guardian would step this gain from -1 to -10 at the end of the DHAR_WFS state, we stepped it from 1 to 3, which seemed to be driving the error signal to zero, but we lost lock partway through this.

H1 ISC - rephasing REFLAIR (PRMI and DRMI locking diode), further locking progress

sheila.dwyer@ligo.org — Sat, 13 Sep 2025 11:44:53 -0700

Author: sheila.dwyer@ligo.org

Report ID: 86903

Elenna, Ryan S, Sheila

This morning Ryan and Elenna were having difficulty getting DRMI to lock, so we locked PRMI and checked the phase of RELFAIR with the same template/PRM excitation described in 84630.

45 MHz phase changed by 7 degrees, 9MHz phase changed by 5 degrees. The attached screenshot shows that the phasing of RFL45 did have an impact on the OLG, and improved the phase margin. In that measurement we also added 25% to the MICH gain.

We accepted the phases in SDF so they were in effect at our next (quick) DRMI lock, but not the gain change.

When we next locked DRMI, we measured the MICH OLG again, and here it seems that the gain is a bit high. We haven't changed the gain in the guardian since this seemed to work well, but the third attached screen shot shows the loop gain.

After this we went to DARM to RF, and manually increased the TR_CARM offset to -7. The REFL power diped to 97% of it's unlocked value while the arm cavity transmission was 24 times the single arm level, so following the plot from 62110 we'd estimate our power recycling gain was between 20 and 30.

Images attached to this report

LHO VE - Sat CP1 Fill

david.barker@ligo.org — Sat, 13 Sep 2025 10:23:27 -0700

Author: david.barker@ligo.org

Report ID: 86901

Sat Sep 13 10:08:37 2025 INFO: Fill completed in 8min 34secs

Images attached to this report

LHO General - Comment to Ops Day Shift Start

ryan.short@ligo.org — Sat, 13 Sep 2025 08:43:31 -0700

Author: ryan.short@ligo.org

Report ID: 86900

Lockloss at DHARD_WFS. After locking DRMI, I tried moving PRM, SRM, and IM4 to get the buildups better, but I could not. I then was stepping through the following states slowly to see if an issue cropped up, and sure enough, after DHARD_WFS had completed I was waiting for DHARD to converge, and alignment was pulled away to eventually cause a lockloss; screenshot attached. I believe this was happening yesterday also. POP18/90 had been slowly degrading since locking DRMI, which may be because only MICH is enabled during DRMI ASC.

Images attached to this report

LHO General - Comment to Ops Day Shift Start

ryan.short@ligo.org — Sat, 13 Sep 2025 08:16:55 -0700

Author: ryan.short@ligo.org

Report ID: 86899

The SEI and SUS trips from the EQ moved alignment of the IMs quite a bit, so to lock XARM_IR, I restored these alignments based on top-mass OSEMs to what they were pre-trip. This was the only intervention needed for initial alignment. Starting main locking now.

LHO General - Ops Day Shift Start

ryan.short@ligo.org — Sat, 13 Sep 2025 07:41:05 -0700

Author: ryan.short@ligo.org

Report ID: 86898

TITLE: 09/13 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 4mph Gusts, 1mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.17 μm/s
QUICK SUMMARY: I will start H1 running an alignment then try locking to see where we're still having trouble.

Wind low, ground motion finally calmed after the large EQ overnight
All other systems nominal

LHO General - OPS EVE Shift Summary

ibrahim.abouelfettouh@ligo.org — Fri, 12 Sep 2025 22:23:09 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 86897

TITLE: 09/13 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
INCOMING OPERATOR: NONE
SHIFT SUMMARY:

IFO is in IDLE for MAINTENANCE (and EQ) for the night. OWL is cancelled due to ongoing corrective maintenance from the most recent outage.

7.4 EQ from Kamchatka, Russia.

Sheila got to it first and untripped the tripped systems (alog 86896). I noticed that some of the suspensions (PRs and SRs) stalled so set them to their respective request states - and they got there successfully.

IFO is still in EQ mode but ringing down.

No HW WDs tripped and everything seems to be "normal" now.

LOG:

None

H1 SEI - Big earthquake, suspensions and ISIs tripped, damped and isolated

sheila.dwyer@ligo.org — Fri, 12 Sep 2025 21:39:46 -0700

Author: sheila.dwyer@ligo.org

Report ID: 86896

ops overvoew screenshot attached. I untripped things but will not try locking tonight.

While untripping suspensions I noticed that oddly IM2 watchdog rms monitors were just below the trip threshold, while the other IMs were 2-3 orders of magnitude smaller. The second screen shot shows this curious behavoir. What about IM2 undamped is so different from the other IMs?

Images attached to this report

H1 General - Glitch rates before/after power outage and ISS loop on/off test

jane.glanzer@ligo.org — Fri, 12 Sep 2025 20:19:29 -0700

Author: jane.glanzer@ligo.org

Report ID: 86895

Summary: omicron glitch rate increases after the power outage, and when the ISS loop is turned off

Using omicron, I made some plots of the glitch rates both before/after the power outage, and then again when the ISS loops were turn on/off. The times chosen were based on the detchar request made by Elenna in alog 86878. For the glitches, I used the omicron frequency/snr parameters of 10 < freq < 1000 Hz and 5 < snr < 500. The first slide in the attached pdf is a comparison of before/after the power outage. It's fairly obvous from the summary pages that the glitch rate increased, but I wanted to quantify just how much it changed. Before the power outage, it was around 45 glitches per hour, and after, it jumped up to about 600 glitches per hour. For both periods, it was around 10 hours of low noise I used for the comparison.

I then did a comparison between when the ISS loop was on versus off. I have found that the glitch rate increased when the ISS loop was turned back off, as can be seen in slide 2. On slide 3, I have summary page plots showing the WFS A YAW error signal, which looks noisier when the ISS loop is off, and the glitchgram below. On slide 4, I made a spectra comparing H1:CALIB_STRAIN_CLEAN during when the ISS loop was off/on, and we can see an increase in noise from ~ 0.06 Hz - 2 Hz, and at slightly higer frequencies of ~ 10 Hz - 40 Hz.

DetChar

Non-image files attached to this report

poweroutageglitchrates.pdf

LHO General - OPS Midshift Report

ibrahim.abouelfettouh@ligo.org — Fri, 12 Sep 2025 18:27:33 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 86894

IFO is still trying to lock. I was given instructions to lock until PREP_ASC_FOR_FULL_IFO but after an initial alignment, the highest we could get to was CARM_TO_ANALOG. DRMI is just very unstable, even with manual intervention to maximize POP signal width.

IFO will keep trying to lock until PREP_ASC_FOR_FULL_IFO. I will change the request per instructions.

LHO General - Ops Day Shift Summary

ryan.short@ligo.org — Fri, 12 Sep 2025 17:28:04 -0700

Author: ryan.short@ligo.org

Report ID: 86891

TITLE: 09/12 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
INCOMING OPERATOR: Ibrahim
SHIFT SUMMARY: Been another busy day of troubleshooting following the power outage. There have been many logs entered with things people have looked into and tried (please see those for more information, as it would be impossible for me to summarize all of it here), but the gist is that we have accepted for now the apparent alignment shift through the IMC, even though this shows much higher reflected power, and reduced the amount of light on the IMC REFL WFS to keep them safe. Since then, we have been trying to relock H1 in this new configuration, but this has been so far plagued with challenges; see Elenna's alog for more on that.
LOG:

Start Time	System	Name	Location	Lazer_Haz	Task	Time End
15:41	FAC	Randy	Hi-bay	N	Moving boom lift outside	16:41
15:54	ISC	Sheila	LVEA	N	Plugging SR785 in for IMC measurement	16:06
16:11	VAC	Richard	LVEA	N	Checking vacuum pump	16:18
17:48	PEM	TJ	LVEA	N	Check DM by HAM6	18:18
18:44	VAC	Gerardo	LVEA	N	Replacing AIP controller on HAM6	19:05
19:42	ISC	Camilla	Opt Lab	N	Getting some bolts and power meter	20:15
19:58	ISC	Sheila, Elenna	LVEA	LOCAL	Adjusting IOT2L waveplate	20:59
21:01	ISC	Elenna	LVEA	N	Check SR785	21:37
21:37	CDS	Marc	MY	N	Finding parts	22:37

H1 IOO - Comment to Power on IMC REFL reduced

ryan.short@ligo.org — Fri, 12 Sep 2025 17:15:53 -0700

Author: ryan.short@ligo.org

Report ID: 86892

After the waveplate adjustment and updating of gains in Guardian, we took an IMC OLG measurement with the IMC locked at 2W input. The UGF was measured at 35.0 kHz.

Non-image files attached to this report

imc_olg_12-09-2025_142122.pdf

H1 ISC - Failing to lock- possible issues with ASC

elenna.capote@ligo.org — Fri, 12 Sep 2025 17:15:15 -0700

Author: elenna.capote@ligo.org

Report ID: 86893

We have been trying to lock the IFO since we reduced the IMC REFL power. DRMI locking has been causing lots of trouble. First time we locked DRMI quickly, but then as the ASC engaged it pulled the buildups away and I couldn't turn off the ASC fast enough before a lockloss occurred. Then, locking DRMI and PRMI starting talking a very long time, 30 minutes or more. Sheila and I tried turning off the DRMI ASC except the beamsplitter. Then, Ryan S touched up the rest of the DRMI alignment by hand. We made it to ENGAGE ASC FOR FULL IFO, but then as the ASC engaged again the POP 18 buildup started dropping, and then we saw large glitches in all the signals- LSC and ASC, then lockloss. We don't know what caused the issues in full IFO ASC, but it seems similar to the DRMI issue- for whatever reason the ASC is not working properly.

We would like to go back to PREP ASC FOR FULL IFO and slowly engage the ASC by hand to figure out what's going wrong. But DRMI locking is still taking 30 minutes or more, and our recent attempt even the beamsplitter ASC didn't work properly. I think it's safe to say we won't be able to lock, let alone observe, for a while. Even if we could solve these ASC issues, we still need to get to laser noise suppression and check various things to ensure the IMC and ISS loops are working properly, we have the right amount of laser power, no significant glitches or degradations, etc.

IOO, OpsInfo

LHO General - OPS Eve Shift Start

ibrahim.abouelfettouh@ligo.org — Fri, 12 Sep 2025 16:10:41 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 86890

TITLE: 09/12 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
OUTGOING OPERATOR: Ryan S
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 14mph Gusts, 8mph 3min avg
    Primary useism: 0.03 μm/s
    Secondary useism: 0.23 μm/s
QUICK SUMMARY:

IFO is LOCKING in DRMI

We still don't know excactly what happened and if we fixed it but:

IMC REFL power was reduced today (alog 86884).
We also think the PSL alignment changed pre/post outage (alog 86882)

Now dealing with DRMI instability. Hoping to get locked.

LHO VE - HAM6, Removed and Replaced The AIP Controller

gerardo.moreno@ligo.org — Fri, 12 Sep 2025 16:00:40 -0700

Author: gerardo.moreno@ligo.org

Report ID: 86889

Removed and replaced the ion pump controller for the annulus system at HAM6.

No issues doing the replacement, but system AIP system continues railed, we wait and we will continue with troubleshooting next week.

LHO VE - Attempt to Activate NEG pump 3

gerardo.moreno@ligo.org — Fri, 12 Sep 2025 15:58:02 -0700

Author: gerardo.moreno@ligo.org

Report ID: 86888

(Anna I., Jordan V., Gerardo M.)

Late entry.

Last Tuesday we attempted to "activate" the NEG pump located on one of the top ports of the output mode cleaner tube, but we opted to do a "conditioning" instead, this due to issues encountered with the gauge related to this NEG pump. Also, what prompted the work on the NEG pump was the "noted" bump on the pressure inside the NEG housing by the gauge, bump on pressure also noted inside the main vacuum envelope, see attachment for pressure at the NEG housing (PT193) and pressure at PT170.

Side note: Two modes of heating for the NEG pump are available, ACTIVATION and CONDITIONING. The difference between both options is the maximum applied temperature, for "conditioning" the max temperature is 250 ^oC, where for "conditioning" the max temperature is 550 ^oC. The maximum temperature holds for 60 minutes.

We started by making sure that the isolation valve was closed, checked it and it was closed. We connected a pump cart+can turbo pump to the system and pump down the NEG housing volume, the aux cart dropped down to 5.4x10^-05 torr, ready for "activation". However, we noted no response from the gauge attached to this volume, PT193 signal remained flat. So, we aborted the "activation" and instead we ran a "conditioning" on the NEG. After the controller finished running the program, we allowed the system to cool down, while pumping on it, then the NEG housing was isolated from the active pumping, hoses and can turbo were removed, then system was returned to "nominal status" or no mechanical pumping on it.

Patrick logged in h0vaclx, but system showed the gauge nominal, and the system did not allowed to turn filaments because pressure is high.

Long story short, the gauge is broken. Next week we'll visit NEG1, and its gauge PT191.

Images attached to this report

H1 SUS - Weekly In-Lock SUS Charge Measurement Analysis

anthony.sanchez@ligo.org — Fri, 12 Sep 2025 14:56:25 -0700

Author: anthony.sanchez@ligo.org

Report ID: 86887

ls /opt/rtcds/userapps/release/sus/common/scripts/quad/InLockChargeMeasurements/rec_LHO -lt | head -n 6
total 295
-rw-r--r-- 1 guardian           controls 160 Sep 9 07:58 ETMX_12_Hz_1441465134.txt
-rw-r--r-- 1 guardian           controls 160 Sep 9 07:50 ETMY_12_Hz_1441464662.txt
-rw-r--r-- 1 guardian           controls 160 Sep 9 07:50 ITMY_15_Hz_1441464646.txt
-rw-r--r-- 1 guardian           controls 160 Sep 9 07:50 ITMX_13_Hz_1441464644.txt
-rw-r--r-- 1 guardian           controls 160 Sep 2 07:58 ETMX_12_Hz_1440860334.txt

In-Lock SUS Charge Measurements did indeed run this Tuesday.

python3 all_single_charge_meas_noplots.py

Cannot calculate beta/beta2 because some measurements failed or have insufficient coherence!
Cannot calculate alpha/gamma because some measurements failed or have insufficient coherence!
Something went wrong with analysis, skipping ITMX_13_Hz_1440859844

Images attached to this report

H1 General - DRMI Histograms

anthony.sanchez@ligo.org — Fri, 12 Sep 2025 14:41:54 -0700

Author: anthony.sanchez@ligo.org

Report ID: 86851

Ive put togther a number of Histograms that can be used for quick glance of locking state performance marks.

Sheila & Elenna wanted some DRMI Stats dating back to Aug 19th .

Images attached to this report

Non-image files attached to this report

output.pdf

H1 IOO - Comment to Power on IMC REFL reduced

elenna.capote@ligo.org — Fri, 12 Sep 2025 14:33:56 -0700

Author: elenna.capote@ligo.org

Report ID: 86886

SDFed the IMC PZT position that we think we like.

Images attached to this report

H1 IOO - Comment to Power on IMC REFL reduced

elenna.capote@ligo.org — Fri, 12 Sep 2025 14:22:19 -0700

Author: elenna.capote@ligo.org

Report ID: 86885

We compensated this change by raising the IMC gains by 6 dB in the guardian. I doubled all the IMC WFS input matrix gains, SDF attached.

Images attached to this report

H1 IOO - Power on IMC REFL reduced

elenna.capote@ligo.org — Fri, 12 Sep 2025 13:57:43 -0700

Author: elenna.capote@ligo.org

Report ID: 86884

Sheila and I went out to IOT2L. We measured the power before and after the splitter called "IO_MCR_BS1" in this diagram of IOT2L. This is listed as a 50/50 beamsplitter. However, there is no possible way it can be, because we measure about 2.7 mW just before that splitter, and 2.45 mW on the IMC refl path and 0.25 mW on the WFS path. So we think it must be a 90/10.

Sheila then adjusted the have wave plate upstream of this splitter so that the light on IMC refl dropped from 2.4 mW to 1.2 mW., as measured from the IMC refl diode.

H1 ISC - Comment to Power on IMC REFL RF PD has increased, plan to decrease it so PD continues to work well

camilla.compton@ligo.org — Fri, 12 Sep 2025 12:55:14 -0700

Author: camilla.compton@ligo.org

Report ID: 86883

Decided we should do this with the IMC OFFLINE. Ryan S put 0.1W into the IMC with the PSL waveplate. This gives 2.37mW on H1:IMC-REFL_DC_OUT16.

Aim to reduce this by a factor of 2 to 1.18mW.

H1 ISC - Alignment change on the PSL table

keita.kawabe@ligo.org — Fri, 12 Sep 2025 12:54:57 -0700

Author: keita.kawabe@ligo.org

Report ID: 86882

(In the attached 1 week trend, [-7 day, -2 day] range is before the power outage and [-1day, 0 day] is after the long high power lock post power outage. Ignore [-2 day, -1 day] because the ISS 2nd loop was messing with the AOM during that time.)

ISS QPD (top right) shows a clearly measurable shift in the alignment mostly in DX (YAW). The QPD is downstream of the PMC, the calibration is supposed to be in mm so nominally it's just 5.4 um but there's a focusing lens in front of it and unfortunately I don't know the focal length nor the distance between the lens and the QPD for now, so the only thing I can say is that the alignment changed downstream of PMC in YAW.

BEA (Bull's Eye Sensor, top left) also shows an alignment shift upstream of PMC. Input matrix of this one is funny, don't read too much into the magnitude of the change. I'm not even sure if it was mostly in PIT or in YAW. (The beam size, 2nd from the top on the left column, also shows a change but I won't trust that because that output is supposed to change when there's an alignment change.)

ISC, PSL

Images attached to this report

H1 IOO - IMC visibility not degrading further today

sheila.dwyer@ligo.org — Fri, 12 Sep 2025 12:53:24 -0700

Author: sheila.dwyer@ligo.org

Report ID: 86881

In our first long lock after the power outage, ISS second loop increased the input power to the IMC by 0.1 W/ hour for 10 hours, MC2 trans was stable, and IMC refl DC increased by 1.7 (mW) per hour (first screenshot)

Last night we left the IMC at 2W, and saw no further degredation. (second screenshot).

Now we increased the power to 60W for an hour and see no further degredation after the transient while the ASC was moving and maybe there was a thermal transient. (third screenshot)

Images attached to this report

H1 ISC - Power on IMC REFL RF PD has increased, plan to decrease it so PD continues to work well

camilla.compton@ligo.org — Fri, 12 Sep 2025 12:14:09 -0700

Author: camilla.compton@ligo.org

Report ID: 86880

Daniel suggested that as the power has increased on the IMC REFL PD (IOT2L D1300357) by a factor of around 3, was 19mW at 60W in, now 60mW at 60Win, we should reduce the power on this diode as it doesn't work well with high powers. H1:IMC-REFL_DC_OUT16

At 2W input, it was 0.73mW, is now 2mW. Aim for a factor of 2 reduction (to make it simple to reduce electronics gains).

Aim to reduce power on IMC REFL to 1mW using IOT2L waveplate when there is 2W incident on IMC.

H1 IOO - Change in IMC visibility

elenna.capote@ligo.org — Fri, 12 Sep 2025 11:44:28 -0700

Author: elenna.capote@ligo.org

Report ID: 86879

A quick calculation of the IMC visibility:

Before power outage:

IMC refl when offline = 46.9

IMC refl when online at 2 W = 0.815

1 - 0.815/46.9 = 0.982

After power outage:

IMC refl when offline = 46.5

IMC refl when online at 2 W = 2.02

1 - 2.02/46.5 = 0.965

So we think we have lost 2.6% of the visibility

H1 DetChar - Detchar request- help understanding our IMC-related glitches.

elenna.capote@ligo.org — Fri, 12 Sep 2025 11:32:28 -0700

Author: elenna.capote@ligo.org

Report ID: 86878

I posted the following message in the Detchar-LHO mattermost channel:

Hey detchar! We could use a hand with some analysis on the presence and character of the glitches we have been seeing since our power outage Wednesday. They were first reported here: https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=86848 We think these glitches are related to some change in the input mode cleaner since the power outage, and we are doing various tests like changing alignment and power, engaging or disengaging various controls loops, etc. We would like to know if the glitches change from these tests.

We were in observing from roughly GPS time 1441604501 to 1441641835 after the power outage, with these glitches and broadband excess noise from jitter present. The previous observing period from roughly GPS 1441529876 to 1441566016 was before the power outage and these glitches and broadband noise were not present, so it should provide a good reference time if needed.

After the power outage, we turned off the intensity stabilization loop (ISS) to see if that was contributing to the glitches. From 1441642051 to 1441644851, the ISS was ON. Then, from 1441645025 to 1441647602 the ISS was OFF.

Starting from 1441658688, we decided to leave the input mode cleaner (IMC) locked with 2 W input power and no ISS loop engaged. Then, starting at 1441735428, we increased the power to the IMC from 2 W to 60 W, and engaged the ISS. This is where we are sitting now. Since the interferometer is has been unlocked since yesterday, I think the best witness channels out of lock will be the IMC channels themselves, like the IMC wavefront sensors (WFS), which Derek reports are a witness for the glitches in the alog I linked above.

DetChar, DetChar-Request

H1 IOO - IMC OLG measurement comparison

sheila.dwyer@ligo.org — Fri, 12 Sep 2025 11:30:56 -0700

Author: sheila.dwyer@ligo.org

Report ID: 86877

Ryan S, Keita, Oli, Sheila

Using the instructions found here we used the netgpib script to get data from an IMC OLG measurement (already checked yesterday 86852).

Oli and I adapted Craig's quick tf plot script to plot two TFs on top of each other, and found some data from Oct 31st 2024 where the IMC OLG was measured with 2W input power 80979 .

We adjusted the gain of the 2024 measurement to match the gain of the 2024 measurement to today's for the first point. The IMC cavity pole is at 8.8kHz, so since this measurement cuts off at 10kHz it will be difficult to get information about the IMC cavity pole from this measurement.

This script is in sheila.dwyer/IOO/IMC_OLG/quick_2tfs_plot.py, legend entries and file names are hardcoded not arguments.

Non-image files attached to this report

imc_olg_12-09-2025_091031.pdf

LHO VE - Fri CP1 Fill

david.barker@ligo.org — Fri, 12 Sep 2025 10:53:09 -0700

Author: david.barker@ligo.org

Report ID: 86876

Fri Sep 12 10:08:39 2025 INFO: Fill completed in 8min 35secs

Images attached to this report

LHO General - Comment to Ops Day Shift Start

sheila.dwyer@ligo.org — Fri, 12 Sep 2025 08:19:22 -0700

Author: sheila.dwyer@ligo.org

Report ID: 86875

Here's an image of a time when the IMC was locked at 2W before the power outage to compare to: archive screenshot

H1 ISC - Comment to Glitch rate from overnight lock

derek.davis@ligo.org — Fri, 12 Sep 2025 08:01:10 -0700

Author: derek.davis@ligo.org

Report ID: 86874

The exponential behavior noted in this alog is related to how frequencies are chosen for the sine-Gaussian wavelets used by Omicron. This type of frequency behavior is what we would expect for broadband glitches, and unfortunately, it does not relate to their physical source in this case.

LHO General - Comment to Ops Day Shift Start

ryan.short@ligo.org — Fri, 12 Sep 2025 07:59:03 -0700

Author: ryan.short@ligo.org

Report ID: 86873

Things looking relatively stable overnight. Some trends and current snapshot of MC TRANS and REFL attached.

Images attached to this report

H1 CDS - Comment to H1 is down due to power outage.

richard.mccarthy@ligo.org — Fri, 12 Sep 2025 07:51:42 -0700

Author: richard.mccarthy@ligo.org

Report ID: 86872

BPA Dispatcher on duty said they had a breaker at the Benton substation open & reclose. At that time, they did not have a known cause for the breaker operation. Hanford fire called to report a fire off Route 4 by Energy Northwest near the 115KV BPA power lines. After discussions with the BPA dispatcher the bump on the line or breaker operation, may have been caused by a fault on the BPA 115KV line causing the fire. BPA was dispatching a line crew to investigate.

LHO General - Ops Day Shift Start

ryan.short@ligo.org — Fri, 12 Sep 2025 07:41:50 -0700

Author: ryan.short@ligo.org

Report ID: 86871

TITLE: 09/12 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 2mph Gusts, 1mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.16 μm/s
QUICK SUMMARY: No observing time for H1 overnight. Investigations will continue today into issues caused by the site power outage on Wednesday.

LHO General - OPS Eve Shift Summary

ibrahim.abouelfettouh@ligo.org — Thu, 11 Sep 2025 19:20:36 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 86870

TITLE: 09/12 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
INCOMING OPERATOR: NONE
SHIFT SUMMARY:

IFO is in DOWN and MAINTENANCE

We are still working on figuring out what happened post-outage that is yielding a glitchy interferometer when locked.

Due to the risk of damaging the interferometer, the decision has been made to cancel the OWL shift, shorten the EVE shift and stay in DOWN until tomorrow.

PSL Dust is fluctuating but has been increasing in the last 2-3 hours. I assume that this is due to the PSL work that was done 2/3 hours ago - this has not been an issue in the past though I've attached a plot.

LOG:

None

Images attached to this report

LHO FMCS - Checking HVAC Fans - Weekly FAMIS 26686

ibrahim.abouelfettouh@ligo.org — Thu, 11 Sep 2025 19:01:56 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 86869

Closes FAMIS 26686. Last checked in alog 86718

Everything below threshold with the outage clearly visible as a blip (mostly in MY and MX fans).

Plots attached.

PEM

Images attached to this report

H1 ISC - Glitch rate from overnight lock

oli.patane@ligo.org — Thu, 11 Sep 2025 18:09:09 -0700

Author: oli.patane@ligo.org

Report ID: 86866

Originally pointed out by Camilla or Elenna earlier today, but I wanted to record it here in case it can help us figure out what the issue is. During last night's low range lock after the power outage (2025-09-11 03:00:47 - 17:42:34 UTC), our glitch rate was way higher than it typically is, and the glitches were mainly confined to several specific frequencies(main summary page, glitches page). I've been able to get some of these frequencies, but there are some frequency lines that I haven't been able to narrow in on the exact frequencies yet.

Here are the frequencies I confirmed, as well as guesses for the other lines:
16.91
24-ish
29.37
37.32
47.41
60-ish
76-ish
90-ish
120-ish
156.97
199.44
250-ish
321.95
409.04
510-ish
660.30

I've plotted them just lined up next to each other as well as plotting the difference in frequency as compared to each one's previous point, and we can see there is a slow exponential increase in the difference between each glitch line frequency. The yellow points are the ones that are around the correct range, but not their exact values.

Additionally, once we turned the ISS Second Loop off at 16:55 UTC, the glitches previously appearing between 500 and 1000 Hz stopped almost altogether, the glitches at 409 Hz and below became a lot more common and louder, and we also saw some extra glitches start above 4000 Hz. We understand the glitches above 4000 Hz, but we aren't sure why the glitches between 500 and 4000 Hz would stop when we did this.

Hoping this might help shine a light on some possible electronics issue?

Images attached to this report

LHO General - OPS Eve Shift Start

ibrahim.abouelfettouh@ligo.org — Thu, 11 Sep 2025 17:14:24 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 86867

TITLE: 09/11 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
OUTGOING OPERATOR: Tony
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 22mph Gusts, 15mph 3min avg
    Primary useism: 0.04 μm/s
    Secondary useism: 0.16 μm/s
QUICK SUMMARY:

IFO is DOWN for MAINTENANCE

With full brevity, something is broken and we don't know why. You can use this alog as a glossary for ideas and tests that our experts have had today:

Much like yesterday, guesses involved the IMC, so Sheila and Ryan went into the PSL with no immediate culprits. IFO was extremely glitchy while observing so we made the call not to try locking at the risk of damaging. If comissioners think of anything to test, they will let me know.

Relevant alogs from throughout the day:

Alog 86865 - Tony's Summary OPS alog.
Alog 86860 - IMC Degradation Pre/Post Outage
Alog 86861 - IMC WFs Comparison Pre/Post Outage
Alog 86857 - Corner Station Dust Monitor Pump High Dust
Alog 86855 - ISS Second Loop Glitch Investigation
Alog 86852 - IMC OLG and Demod Phase Check
Alog 86848 - Extreme glitching correlated with IMC WFs

Alogs are still being written as it's been a long and busy day. I will add more throughout the shift.

H1 General - Thursday Ops Day shift defeat

anthony.sanchez@ligo.org — Thu, 11 Sep 2025 16:42:28 -0700

Author: anthony.sanchez@ligo.org

Report ID: 86865

TITLE: 09/11 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
INCOMING OPERATOR: Ibrahim
SHIFT SUMMARY:

H1 Started the day locked and Observing but something was strange. H1 h(t) triggers across multiple frequencies.
When we went to commissioning and skipped the Calibration due to the very obvious fact that the IFO was not running well.
Sheila and Oli went out on the floor to inject some test signals into H1:IMC-REFL_SERVO_COMEXCEN.

Sheila, Elenna, Camilla, Ryan, Daniel, Oil, & TJ were trying to find out why the IFO is behaiving so abnormally for most of the day.
Journalist came into the Control room for a quick tour with Fred.

There are fears that we may accidentally burn something if we try to lock, and perhaps the EVE's and Owls may be canceled.
Dust counts in the Anti-Room were Very high today and after TJ went to the Mech Mez to check and adjust the Dust pumps he did discover that the Vacuum lines for the Dust mon pumps were not securely connected.... which could explain the dust. After that the dust levels did seem to fall.

Ryan & Sheila went into the PSL room to see if there was any obvious issues.

Rahul checked out the Input arm su spensions and didn't find anything strange.

LOG:

Start Time	System	Name	Location	Lazer_Haz	Task	Time End
14:57	FAC	Nellie	Optics lab	N	Technical Cleaning	15:13
16:06	IMC	Sheila, Elenna, Oli	LVEA	N	Checking on the IMC	18:06
17:54	SEI	Jim	LVEA	N	Trippn HAM3	18:24
18:48	PSL&PEM	Ryan S	LVEA	N	Checking the PSL environmental controls	19:18
20:25	JAC	Corey	Optics / vac lab	N	working on Jac table	20:25
20:43	IMC	Daniel & Ellenna	LVEA	N	Checking for oscillations on IMC	21:13
22:11	PSL	Sheila & Ryan S	PSL room	Yes	Checking for smell of burnt in PSL	22:56

H1 CDS - Comment to Corner station dust monitors were recording high values overnight due to central pump offline

thomas.shaffer@ligo.org — Thu, 11 Sep 2025 15:13:43 -0700

Author: thomas.shaffer@ligo.org

Report ID: 86864

The pump was running especially hot and the gauge showed no vacuum pressure. I turned off the pump and checked the hose connections. The filter for the bleed valve was loose, the bleed screw was full open, and one of the pump filters was very loose. after checking these I turned it back on and it immediately sucked to 20inHg. I trimmed it back to 19inHg and then rechecked a few hours later to confirm it had stayed at that pressue. The pump was also running much cooler at that point as well.

PEM

H1 PEM - 24 days with dust monitor 10 high on BSC2

thomas.shaffer@ligo.org — Thu, 11 Sep 2025 14:45:48 -0700

Author: thomas.shaffer@ligo.org

Report ID: 86863

Continuing from alog86631, here's 24 days with DM10 mounted up high on BSC2 on a catwalk. The 3 Tuesdays are labled and I also plotted DM6 as a comparision, which has not moved and stayed in the mega cleanroom.

Images attached to this report

H1 IOO - IMC transmission degraded after power outage, and in 60W locks since the power outage

sheila.dwyer@ligo.org — Thu, 11 Sep 2025 14:15:01 -0700

Author: sheila.dwyer@ligo.org

Report ID: 86860

Compaing now to a time before the power outage, the ISS diffracted power is now the same (3.6%). The PMC transmission has dropped by 2%, and the PMC reflection has increased by 3.5%.

Looking at IMC refl, before the power outage when the IMC was locked with 2W input power.

time	IMC refl	refl percent of before outage	MC2 trans	MC2 trans % of before outage
9/10 8:12 UTC (before power outage, 2W IMC locked)	0.74		317
9/11 00:22 UTC (IMC relocked at 2W after outage)	1.15	155%	312	98%
9/11/1:50 UTC (after first 60 W and quick lockloss, IMC relocked at 2W)	1.27	171%	310	97%
9/11 18:17 UTC (after overnight 60W lock)** had one IMC ASC loop off	2.06	278%	278	87%
9/11 19:22 UTC (after all IMC ASC on)	2.13	287%	301	95%
9/11 21:17 UTC (after sitting at 2W for 3 hours)	2.03	274%	303	95%

The attached screenshot shows that the ISS second loop increased the IMC input power during the overnight 60W lock to keep the IMC circulating power constant.

Images attached to this report

H1 ISC - Comment to Looking into if ISS 2nd Loop is causing IFO Glitches

camilla.compton@ligo.org — Thu, 11 Sep 2025 14:01:21 -0700

Author: camilla.compton@ligo.org

Report ID: 86862

Ryan, Sheila

Ryan and Sheila noticed that the PSL-PMC_TEMP changed ~0.5deg without the set point changing. After looking into his we compared to the April power outage where it came back 1deg cooler. We therefore don't think this is causing us any issues. Both bower outages plotted in attached.

We did notice tough that some glitches in PMC-TEMP_OUT started ~ 31st May 2025 and have been present since, plot attached. Tagging PSL.

PSL

Images attached to this report

H1 ISC - Comparing IMC WFS during IMC offline before and after outage...but then it changed

oli.patane@ligo.org — Thu, 11 Sep 2025 13:58:25 -0700

Author: oli.patane@ligo.org

Report ID: 86861

After the lockloss today, we took the IMC offline for a bit, and I moved the IMC PZTs back to around where they had been before the outage. The time from then when we had the IMC offline was September 11, 2025 18:07:32 - 18:11:32 UTC. I then found a time from before the outage when we last had the IMC offline, which was September 02, 2025 17:03:02 - 17:19:02 UTC, and verified that the pointing for MC1 P and Y were about the same, as well as the IMC PZTs are in the same general area.

I then looked at IMC-WFS_{A,B}_DC_{PIT,YAW,SUM}_OUT during these times. The dtt, where blue is the Sept 2 time and red is the time from today, seems to show similar traces. The ndscopes (Sept2, Sept11) show many of those channels to be in the same place, but a few aren't - H1:IMC-WFS_A_DC_PIT_OUT has changed by 0.3, H1:IMC-WFS_A_DC_YAW_OUT has changed by 0.6, and H1:IMC-WFS_B_DC_YAW_OUT has changed by 0.07. However, after this time, we relocked the IMC for a while, and then went back to offline, between 19:25:22 - 19:31:22 UTC, and these values changed. I've added that trace to the dtt in green, and it still looks about the same. Many of the WFS values have changed though.

Images attached to this report

H1 SEI - HAM3 H2 CPS is noisy, has been for a while

jim.warner@ligo.org — Thu, 11 Sep 2025 13:23:14 -0700

Author: jim.warner@ligo.org

Report ID: 86859

I don't really think this is related to the poor range, but it seems that one of the cps on HAM3 has excess high frequency noise and has been noisy for a while.

First image is 30+ day trends of the 65-100hz nad 130-200hz blrms for the HAM3 cps. Something happened about 30 days ago that cause the H2 cps to get noisy at higher frequency.

Second image are rz location trends for all the HAM ISI for the last day around the power outage. HAM3 shows more rz noise after the power outage.

Last image are asds comparing HAM2 and HAM3 horizontal CPS. HAM3 H2 shows much more noise above 200hz.

Since finding this, I've tried power cycling the CPS on HAM3 and reseating the card, but that so far has not fixed the noise. Since this has been going for a while, I will wait until maintenance to try to either fix or replace the card for this CPS.

Images attached to this report

H1 ISC - Comment to Looking into if ISS 2nd Loop is causing IFO Glitches

camilla.compton@ligo.org — Thu, 11 Sep 2025 12:05:19 -0700

Author: camilla.compton@ligo.org

Report ID: 86858

IM4 trans with IMC locked at 2W before the power outage was PIT, YAW: 0.35,-0.11. After the outage PIT, YAW: 0.39,-0.08. Plot attached. These are changes of 0.04 in PIT, 0.03 in YAW.

Oli and Ryan found that the alignment on IMC REFL WFS was the same but PSL-ISS_SEONDLOOP different, this makes us think the alignment change is in the MC or IMs. The IMs osems haven't changed considerably.

Images attached to this report

H1 CDS - Corner station dust monitors were recording high values overnight due to central pump offline

david.barker@ligo.org — Thu, 11 Sep 2025 11:40:53 -0700

Author: david.barker@ligo.org

Report ID: 86857

Tony, TJ, Dave:

After the power outage the CS dust monitors (Diode room, PSL enclosure, LVEA) started recording very large numbers (~6e+06 PCF). TJ quickly realized this was most probably a problem with the central pump and resolved that around 11am today.

2-day trend attached.

Images attached to this report

H1 ISC - Comment to Looking into if ISS 2nd Loop is causing IFO Glitches

elenna.capote@ligo.org — Thu, 11 Sep 2025 11:26:15 -0700

Author: elenna.capote@ligo.org

Report ID: 86856

Here are three spectrograms of the IMC WFS DC YAW signal: before the power outage, after the power outage with the ISS on, after the power outage with the ISS off.

I don't see glitches in the before outage spectrogram, but I do see glitches in BOTH the ISS on and ISS off spectrograms. The ISS off spectrogram shows more noise in general but it appears that it has the same amount of nonstationary noise.

Images attached to this report

H1 ISC - Looking into if ISS 2nd Loop is causing IFO Glitches

camilla.compton@ligo.org — Thu, 11 Sep 2025 11:19:51 -0700

Author: camilla.compton@ligo.org

Report ID: 86855

Sheila, Ryan S, Tony, Oli, Elenna, Camilla, TJ ...

From Derek's analysis 86848, Sheila was suspicious that the ISS second loop was causing the glitches, see attached. The ISS turning on on a normal lock vs in this low-range glitchy lock attached, it's slightly more glitchy in this lock.

The IMC OLG was checked 86852.

Sheila and Ryan unlocked the ISS 2nd loop at 16:55UTC. This did not cause a lockloss although Shiela found that the IMC WFS sensors saw a shift in alignment which is unexpected.

See the attached spectrum of IMC_WFS_A_DC_YAW and LSC_REFL_SERVO (identified in Derek's search), red is with the PSL 2nd loop ON, blue is off. There is no large differences so maybe the ISS 2nd loop isn't to blame.

We lost lock at 17:42UTC, unknown why but the buildups starting decreasing 3 minutes before the LL. It could have been from Sheila changing alignments of the IMC PZT.

Sheila found IMC REFL DC channels are glitching whether the IMC is locked or unlocked, plot attached. But this seems to be the case even before the power outage.

Once we unlocked, Oli out the IMC PZTs back to their location before the power outage, attached is what IMC cameras looks like locked at 2W after WFS converged for a few minutes.

PSL

Images attached to this report