August 5th Randy and I removed two braces from the BSC work platform at EY. These were used to stabalize the work platform by connecting it to the flange around the BSC chamber. These had been in place since the platform was originally put in place. These were the only two still in place.

Fri Aug 15 10:08:39 2025 INFO: Fill completed in 8min 36secs

TITLE: 08/15 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Lock Acquisition
INCOMING OPERATOR: Oli
SHIFT SUMMARY: Quiet shift with H1 observing for almost the whole duration except for a lockloss right at the end. Initial alignment just finished, now starting main locking sequence.
LOG:

• 01:38 - Dropped observing to address rising ITMX violin mode 2
  • VIOLIN_DAMPING Guardian to 'DAMPING_ON_SIMPLE'
  • Applied nominal gain of -15
  • VIOLIN_DAMPING back to 'DAMP_VIOLINS_FULL_POWER'
• 01:40 - Resumed observing
• 04:45 - Lockloss - alog86372
• 05:06 - Alignment finished, starting lock acquisition

Lockloss @ 04:45 UTC after 18+ hours locked - link to lockloss tool

Perhaps caused by the smallest of ETMX glitches starting in L3 right before the lockloss? Doesn't exactly look to me like a usual one of these, though. Otherwise, no obvious cause.

Jumping right into an alignment given the long lock stretch.

TITLE: 08/14 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 151Mpc
INCOMING OPERATOR: Ryan S
SHIFT SUMMARY: Locked for 13 hours. We had calibration and comissioning this morning, where we rode through a few earthquakes with help from some new configuration (alog86364). Ryan S noticed ITMX mode 2 has been growing slowly for this entire lock. It was never damped because it was almost non existant at the start of the lock. He will address it when practical.
LOG:

• 1023 GRB E589922
• 1530 Out of observing for calibration and commissioning
• 1635 Earthquake mode activated
• 1706 High ASC gain turned on to test during earthquake
• 1740 Transitioned ASC back
• 1906 Observing

TITLE: 08/14 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 153Mpc
OUTGOING OPERATOR: TJ
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 25mph Gusts, 16mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.12 μm/s
QUICK SUMMARY: H1 has been locked for 12.5 hours and observing since commissioning wrapped up this morning.

• Wind moderate with gusts over 20mph, other ground motion low
• All other systems nominal

I noticed the ~500Hz violin mode peak is high in DARM and saw that indeed ITMX mode 2 is elevated and has been growing this entire lock stretch. It looks like the gain was never turned on for this mode, which happens if the monitor for a mode is low enough when the full power damping is turned on. Since the violin damping Guardian sees the mode is growing, it's constantly zeroing the gain in the damping filters, so we've been unable to turn on the nominal gain of -15. To fix this, we would have to take H1 out of observing, take the VIOLIN_DAMPING node to 'DAMPING_ON_SIMPLE', then back to 'DAMP_VILINS_FULL_POWER' so that the node resets its "node growing" checks and sees the mode needs damping. I plan to do this if either L1 drops out of observing or if the 500Hz peak on DARM gets up to 10^-16 m/Hz^-1/2

I ran a bruco yesterday that showed lots of low-ish broadband coherence of SRCL, PRCL and MICH.

I have a previous good measurement of the PRCL coupling, so I used that to iteratively fit an improved feedforward. Based on the last test I did of the PRCL feedforward, I am not certain that just adjusting the gain is good enough right now to reduce the coupling significantly. screenshot

I also measured and tried to fit a better SRCL feedforward. The challenge continues to be fitting the low and high frequency behaviors of the SRCL coupling simultaneously. The misfit of the high frequency behavior continues to create a broad bump of SRCL noise around 100-300 Hz.

I made some small improvements of the SRCL coupling, but there is still room for more improvement. screenshot

I still need to remeasure and refit the MICH feedforward.

The new SRCL FF is in FM6 and the PRCL FF is in FM8. I updated the guardian and the SDF.

Edgard, Ivey

This Tuesday Oli ran into issues installing the new blend filters and new SR3 Yaw transfer function fits for the OSEM estimator (see LHO: 86319). An error from the cplxpair function, which pairs complex conjugates, appeared only when converting the fit from zpk into state space. Somehow, this would introduce a small but significant difference between any two complex pairs, which would cause the computer to reject it as a complex pair. To resolve this issue, we ran a function to average each complex pair. We tested it with our mock PR3 model in the lab, and this seemed to fix the error cplxpair was encountering.

We were not able to reproduce the error that Oli noticed with the blend filters in our lab, but we will look more into this, and hopefully the issue will be fixed by next Tuesday when Oli tests the estimator again with the new fits.

The new cleaned SR3 yaw fits were added to SusSVN and can be found here '~/SusSVN/sus/trunk/HLTS/Common/FilterDesign/Estimator/fits_H1SR3_Y_2025-08-05.mat'. More on the fits LHO: 86233.

The new blend filter with updated fits can be found here '~/SusSVN/sus/trunk/HLTS/Common/FilterDesign/Estimator/Estimator_blend_skinnynotch_SR3yaw_20250723.mat'. More on the blend filter LHO: 86265.

DQ shifters: Riley McNeil and Emil Lofquist-Fabris

• Daily observing duty cycle: 57.05%, 67.36%. 99.68%, 59.91%, 91:23%, 69.16%, 100.00%. Week average: 77.77%.

• The BNS range this week sat around 150 Mpc, however there were a few sudden drops in the range by about 5-10 Mpc. These were seen on Tuesday, Thursday, and Friday.

• There were several issues with the squeezer this week that resulted in sudden increases in noise and glitching, as well as a couple drops from observing.

• There was a recurring spike in the y-manifold beam tube motion [X] at 17:00 every day. This was seen in the previous week as well, this is caused by the daily dewar fill noise at the Y-manifold cryopump. (alog)

• There was also recurring noise from ~11:00-14:00 in several corner station accelerometers also seen in previous shifts.

• Just above 20 Hz (~22-25 Hz) there has been a line of glitching that we believe to be light scattering. This has been seen since at least the start of July 2025.

  • There has also been a lot of glitching/noise from ~20-40 Hz, consistent with previous weeks, likely from an AC unit housed inside the VPW. (alog)

• There was a 34 hour lock segment this week, from Tuesday August 5th 22:19 to August 7th 08:31.

  • The detector also spent all of Sunday observing as well.

See full report here: https://wiki.ligo.org/DetChar/DataQuality/DQShiftLHO20250804

This morning a 6.2 magnitude earthquake near Vanuatu happened during the commissioning window, so we tested the asc gain reversion scripts Elenna came up with in this alog. It took a little longer than I would have liked to get the scripts working, so we didn't actually transition until basically the peak ground velocities, but the transition went pretty smoothly. I think this eq is tied for the biggest  we stayed locked through for all of O4.

Attached image shows ground velocities on the top row (both peakmon and the ITMY Z STS 30-100mhz blrms, second row is the ISC_LOCK state, third and fourth show channels related to the asc transition. Fourth row is the first gain changed by the script CHARD Y, the third row is the SRCL FF gain, which is the last thing changed in the script. The dashed white vertical lines on the CHARD trace and the top row ground traces show the time the transition took to complete.

Even if the transition was a little late I think that this test likely still saved the lock, I have often seen on eqs like this that the IFO stays locked through the peak ground motion, but loses lock some time shortly after, while the eq is still ringing down.

There is still a lot of work to be done as the transition is currently handled by a couple of scripts on the ISI_CONFIG overview medm and the transition will knock us out of Observe, still unclear what the best way to automate this would be, but still a pretty good test.

Thu Aug 14 10:08:28 2025 INFO: Fill completed in 8min 24secs

Running another calibration measurement today following the usual broadband and simulines.

Simulines Start:

PDT: 2025-08-14 08:36:33.095985 PDT
UTC: 2025-08-14 15:36:33.095985 UTC
GPS: 1439221011.095985

Simulines End:

PDT: 2025-08-14 08:59:53.303431 PDT
UTC: 2025-08-14 15:59:53.303431 UTC
GPS: 1439222411.303431
 

Files:

2025-08-14 15:59:53,136 | INFO | File written out to: /ligo/groups/cal/H1/measurements/DARMOLG_SS/DAR
MOLG_SS_20250814T153633Z.hdf5
2025-08-14 15:59:53,145 | INFO | File written out to: /ligo/groups/cal/H1/measurements/PCALY2DARM_SS/
PCALY2DARM_SS_20250814T153633Z.hdf5
2025-08-14 15:59:53,150 | INFO | File written out to: /ligo/groups/cal/H1/measurements/SUSETMX_L1_SS/
SUSETMX_L1_SS_20250814T153633Z.hdf5
2025-08-14 15:59:53,156 | INFO | File written out to: /ligo/groups/cal/H1/measurements/SUSETMX_L2_SS/
SUSETMX_L2_SS_20250814T153633Z.hdf5
2025-08-14 15:59:53,161 | INFO | File written out to: /ligo/groups/cal/H1/measurements/SUSETMX_L3_SS/
SUSETMX_L3_SS_20250814T153633Z.hdf5
 

TITLE: 08/14 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 153Mpc
OUTGOING OPERATOR: Tony
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 2mph Gusts, 0mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.10 μm/s
QUICK SUMMARY: Observing for 4 hours, automated relock. Environment is calm. The only active alarm is the known vacuum PT242B pressure. Planned calibration and commissioning time today 1530-1930 UTC.

TITLE: 08/14 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 153Mpc
INCOMING OPERATOR: Tony
SHIFT SUMMARY: Very quiet shift with H1 observing throughout, despite a couple hours of high winds blowing through with gusts briefly over 40mph. There's a M5.6 quake inbound from the South Pacific, but the EQ response tool just places it in the lower bound of the "earthquake" region. H1 has now been locked for 14.5 hours.

In consultation with Sheila, I've added a new flag in lscparams.py called "ignore_sqz" (currently set to False) which when True, removes SQZ_MANAGER from ISC_LOCK's managed nodes list and sets up ISC_LOCK such that no requests are made of SQZ_MANAGER. I've additionally removed all instances of ISC_LOCK requesting SQZ_MANAGER to 'NO_SQUEEZING.'

The motivation for this stems from an issue encountered earlier this week (alluded to in Monday's shift summary) where after H1 dropped observing from the SQZ PMC having to relock, SQZ_MANAGER eventually stalled (which is not unexpected) and ISC_LOCK then requested it to 'NO_SQUEEZING' for a then-not-well-understood reason. After looking into the frequently used "unstall nodes" decorator in ISC_LOCK, I learned that the revive function it calls simply requests the stalled subordinate node to whatever its last requested state was. The catch here is that the last requested state refers only to what the manager's last request was to the subordinate, not whatever request a user, other node, or standalone script may have made, as the manager node has no way of knowing about requests outside of its own. A discrepancy between a manager node's last request to a subordinate and a different request to that subordinate can be seen with a notification on the manager saying the subordinate's request changed.

My understanding of the sequence of events that led to the confusion on Monday is that commissioners had been working with the squeezer and wanted its Guardian manager node to remain in 'NO_SQUEEZING' while H1 was relocking following their work. In its design at the time, in a few different states such as 'INJECT_SQUEEZING', ISC_LOCK would check the status of SQZ_MANAGER, and if it was in 'NO_SQUEEZING', move on with the state and re-request SQZ_MANAGER to 'NO_SQUEEZING'. This makes SQZ_MANAGER's manager's last request 'NO_SQUEEZING', so when SQZ_MANAGER later stalled, it was requested back to 'NO_SQUEEZING' even though a user had set SQZ_MANAGER to its nominal state sometime later. This is why I've removed requests to 'NO_SQUEEZING' in ISC_LOCK; I believe it's a sound assumption that if SQZ_MANAGER is in 'NO_SQUEEZING', someone wants it there and Guardian should just move on. Further, this makes it so that the only request ISC_LOCK ever makes to SQZ_MANAGER is its nominal state (except in 'DOWN', of course, which would then later get updated to the nominal), meaning there should be no confusion as to what its last request was.

Changes have been saved and committed to svn, but ISC_LOCK has not yet been loaded. This should be done at the next drop from observing.

Leo, Jennie, Camilla, WP 12694

Jennie followed instructions for set up in 85775. We removed the SQZ beam iris at the bottom of the LPM (added for alignment capture during OFI vent work). Then took beam profiles in this SQZ path of the SEED beam with various PSAMS settings, adjusted PSAMS settings as in 85775 and used the servo for nominal settings. All data is attached. Jennie then reverted settings back to nominal.