Link to report here.

• Average observing time: 71.2%
• Range was generally between 145-160 Mpc throughout the week, except for a drop at 1100-1200 on Wednesday Sept 3 when it was around 135 Mpc, mostly likely due to SQZ issues
• EQs and anthropogenic ground motion may contribute to increased glitch rates and noise in h(t) several times throughout the week
• Tuesday had quite strong violin modes (esp. 500 Hz) after relocking
• Magnetic corner station plots for Thursday Sept 4 are blank
• Common Hveto channels throughout the week: H1:ASC-Y_TR_A_NSUM_OUT_DQ, H1:ASC-Y_TR_B_NSUM_OUT_DQ, H1:ASC-Y_TR_B_YAW_OUT_DQ, H1:ASC-Y_TR_A_PIT_OUT_DQ, H1:ASC-Y_TR_A_YAW_OUT_DQ, H1:ASC-CSOFT_Y_OUT_DQ, H1:ASC-DSOFT_Y_OUT_DQ
• Fscan-Observing lines stayed around 2700-3000 throughout the week

In the past, when heating up the OM2 heater, we have noticed that the low frequency sensitivity improves, for example alog 78652.

I wanted to make this comparison again, but we have seen that the squeezing performance can be variable, so I first chose to compare a no squeezing time with OM2 hot and cold.

It's also important to note that the calibration has likely changed with the hot OM2. Some of that can be corrected with the TDCFs. However, we saw that the required SRCL offset to minimize SRC detuning with OM2 hot was significantly different, alog 86737. This means that the sensing function is probably significantly different, causing some change in the calibration that is not compensated. We didn't take any calibration measurements with hot OM2, so we have no idea how much or how to compensate the calibration change.

With OM2 hot, the coherence of DARM with SRCL and MICH increased, although SRCL can explain most of the excess noise between the two times. Interestingly, the coherence of DARM with jitter decreased with OM2 hot. There is no significant change in the coherence with PRCL.

Here is a comparison of the cold and hot OM2 times, using GDS CALIB STRAIN CLEAN.

I performed a simple coherence subtraction of SRCL alone, and SRCL and MICH together. I checked that there is no significant coherence between SRCL and MICH.

Given the possible issue with the calibration, I am not certain how comparable the low frequency noise is. There is a small increase in the noise up to 30 Hz with OM2 hot, even with the above subtractions applied.

H1 ISI CPS Sensor Noise Spectra Check - Weekly Famis 26655

BSC high freq noise is elevated for these sensor(s)!!!
    
ITMY_ST1_CPSINF_H3
 

In 86589, Jeff points out mysterious noise seen in SRC2 Y CTRL between 1 and 3 Hz that is only seen when the SR3 estimator is fully on with the L to P contribution included.

To verify this, I plotted some other times with the estimators ON and OFF, and looking at those different times, I was able to confirm that the unknown increase in noise Jeff points out between 1 and 3 Hz is NOT caused by the estimator, but by some other noise source in passing.

Camilla, Sheila

We did a series of quick measurements related to filter cavity backscatter, a follow up with plots will come soon.

Injection for linear coupling (varies from day to day, we are repeating to see how much it changes, 1st screenshot):

• /ligo/home/sheila.dwyer/Noise_Budget_repos/excesspowerprojections/data_files/FC_backscatter.xml
• refs 32-34

Fringe wrapping (scattered amplitude seems slightly lower than in 2024 when moving ZM2, slightly higher when moving ZM5):

• userapps/sqz/h1/Templates/dtt/DARM_scatter_2025_0903.xml
• quiet refs: 33-37
• ZM2 test L excitation 100 counts at 1 Hz, ref 38-40
• ZM5 test L excitation 100 counts at 1 Hz, ref 41-43

Open loop gain (also varies from day to day):

• ref 12 Sept 3rd
• ref 18 (8% higher gain than on the 3rd)

FC2 M1/M3 cross over:

• userapps/sqz/h1/Templates/dtt/filter_cavity/FC2_M1_M3_crossover.xml
• cross over looks to be 1 Hz, with an instability at 1.3 Hz and less than 3dB of gain margin
• while doing this I moved the location of a filter in FC2, which had to be accepted in SDF and updated in the guardian.  This filter is set in the init state of the guardian, which should probably be moved to down instead of init.  I also copied over a boost filter, but after doing the measurements it is clear we can't use that boost as is, so it is off.

We tuned FIS around 100HZ and then changed the SQZ angle +/-5deg, plot attached. Shiela thinks this could help us constrain thermal noise in the future.

Plot attached of today's data (SRCL offset at nominal -382) compared to last weeks while OM2 was hot (with SRCL offset tuned at -235). Solid lines are cold OM2, dashed lines are hot OM2. FIS is better with cold OM2 as expected.

We noticed that mean SQZ was different <100Hz with the OM2 hot vs Cold. This persisted if I changed the averages so wasn't caused by a glitch and also seemed to be increased looking at Sheila's 86736 data too. Changed SRCL offset to see if this was the cause but it didn't appear to be. Plot attached, so the cause is OM2.

Mon Sep 08 10:07:09 2025 INFO: Fill completed in 7min 5secs

Gerardo confirmed a good fill curbside. TC-A became good again at 05:56 this morning and looks nominal in today's fill.

Gerardo inspected the TCs and suspects TC-A wiring had been moved by animal activity. Why it corrected itself this morning is a mystery.

FAMIS 31102

The RefCav alignment has been drifting again this week and causing the signal on the TPD to drop, so this could use a touchup. I'll try to find some opportunistic time to do this after a lockloss either today or later this week.

No other major events of note.

TITLE: 09/08 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 153Mpc
OUTGOING OPERATOR: Oli
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 5mph Gusts, 3mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.09 μm/s
QUICK SUMMARY:

• We've been locked for 5 hours, 1 lockloss overnight
  • Several small earthquakes overnight
• 09:25 UTC Observing
• Low wind
• Comissioning planned from 15:30 - 18:30 UTC

TITLE: 09/08 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 154Mpc
INCOMING OPERATOR: Oli
SHIFT SUMMARY:

IFO is in NLN and OBSERVING as of 14:13 UTC (37 hr lock!)

LOG:

TITLE: 09/07 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 159Mpc
INCOMING OPERATOR: Ibrahim
SHIFT SUMMARY: We stayed locked the whole shift, over 31 hours.
LOG: No log.

• A small earthquake from Alaska came through around 14:45 UTC
• The wind has picked up in the last 4 hours
• Looking at the noise shelf that appears in the 1-3 Hz groundmotion, EndX sees the most motion, there doesn't seem to be a noticible arrival time delay between any of the arms and the CS. Yesterday it started around 13:45 UTC and went until 20:50 UTC

TITLE: 09/07 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 154Mpc
OUTGOING OPERATOR: Ryan C
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 14mph Gusts, 9mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.12 μm/s
QUICK SUMMARY:

IFO is in NLN and OBSERVING as of 14:13 UTC (31 hr lock!)

Sun Sep 07 10:07:43 2025 INFO: Fill completed in 7min 39secs

Good fill. TC-A continues to be all over the shop, occasionally giving believable readings. Similar to yesterday it was TC-A which had a larger Delta-temp and triggered the end-of-fill, closely followed by TC-B.

TITLE: 09/07 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 154Mpc
OUTGOING OPERATOR: Oli
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 5mph Gusts, 4mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.12 μm/s
QUICK SUMMARY:

• We've been locked for almost 23 hours
  • We dropped Observing from 12:21 to 14:13 UTC from SQZ issues alog86797
• Some of the FOMs have a notification about wanting to be restarted due to obsolete binaries for "MEDM, caRepeater, xterm, and python"

Oli, Camilla (Oli did the work, I just wrote down what they did!)

Oli had been troubleshooting SQZ and found that when the OPO ISS tried to engage, it go to 10V and then unlocked. The OPO Trans output was only ~50uW on LOCKED_CLF_NO_ISS. This was meaning the ISS was maxing out it's 0-10V range to get to the nominal setpoint of 80uW. 

We could see on SQZT0 medm that the SHG output power was 81.2mW when nominal is ~ 100mW. This will reduce the available power to the OPO path. We followed the wiki to increase the SHG power (I should make the instructions of when to do this clearer) by adjusting the SHG SETTEMP. Doing this, Oli brought SHG power up from 81mW to 92mW. 

Then the OPO Trans output was ~65uW on LOCKED_CLF_NO_ISS (nominal 80uW). So Oli moved the waveplate between the +200MHz AOM and the SHG Rejected PD in the "to OPO" path to increase the available power sent into SHG launch. Then the AOM had enough range and the OPO could lock in LOCKED_CLF_DUAL_NO_ISS. 

Then Oli had issues with getting the FC to lock in Green so followed the wiki instructions to in do that too, trending to last good alignments with ZM3 (had moved 20urad on FC lockloss from ASC turning off) and then manually locking FC and increasing power with FC2, (FC1, ZM3) alignments. Oli increased the power in the 0,0 mode form 35 to 65 with alignments. Nominally this is > 80 but it had only been at 50 in the last lock, probably from the SHG power being low. 

Back to Observing 7:13amPT. 

J. Kissel

After today's H1 SUS SR3 Pitch Estimator's inclusion of the Sus. Point L to M1 P feed forward from the HAM5 ISI GS13s (where we had mistakenly only installed Sus. Point P to M1 P) -- see LHO:86567, I now compare the times of ASC signals (using 0.02 Hz binwidth, 64 sec FFT chunks, 30 averages, and a Hanning window with 50% overlap):
    2025-08-20 18:29 UTC - Both P and Y Estimators are OFF 
    2025-08-24 18:18 UTC - Both P and Y Estimators are ON, but for the P estimator, only the Sus. Point P to M1 P contribution is included in the GS13 FF
    2025-08-26 22:00 UTC - Both P and Y Estimators are ON, and for the P estimator, both P to P and L to P contributions are included in the GS13 FF.

I'm showing only the control signals, and only the ASC DOFs which are impacted by SR3: DHARD, MICH, SRC1, and SRC2; both pitch and yaw.

In All DOFs, the 0.64 and 0.75 Hz modes that had been made worse with only the P to P model of suspension point contribution have now been restored to no-estimator levels.
In some DOFs, the 1-10 Hz broadband motion is just barely improved, but enforces the conclusion that SR3 is only partially, if not 'not the dominate contribution' to the ASC signals. 
Here's a fun one for you -- look at SRC2 Y CTRL -- and look at how much the SRC2 *yaw* motion has changed from including the *longitudinal* suspension point contribution to M1 *pitch* top mass. #ThrowsHandsInAir

But -- overall -- with the improvements and all design intent included -- the SR3 P and Y estimators slightly improve the ASC noise from 1 to 10 Hz. Great!

As Oli notes in LHO:86551 comparing all of these different configurations from totally different days and times is dubious. We'll get "official" versions of all of these ON vs. OFF configurations on Thursday 8/28.

I also attach the local estimator metrics for pitch described in LHO:86553, comparing "only Sus Point P to M1 P modeled contribution" against "P to P and L to P sus point to M1 contribution." That similarly shows that L to P contribution forms a good fraction of the signal needed for damping.