We've recently been having some issues with SRM tripping during initial alignment and during DRMI acquisition, alog87370 for example. After consulting with Jeff K, I've bumped up the trip thresholds as listed below. This was based off of the last few trips, so hopefully it has enough of a buffer now. Saved in the safe and observe sdfs.

Lock loss 1444317365

No obvious cause, ended a 29.5hour lock.

TITLE: 10/12 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 154Mpc
OUTGOING OPERATOR: Ryan S
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 9mph Gusts, 5mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.28 μm/s 
QUICK SUMMARY: Locked for 28.7 hours, range is stable, no alarms, no alerts overnight.

TITLE: 10/12 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 153Mpc
INCOMING OPERATOR: Ryan S
SHIFT SUMMARY:

IFO is in NLN and OBSERVING (19 hr lock!)

Range is stable. Environment is stable. Locked for the whole shift.

LOG:

None

TITLE: 10/11 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: 15mph Gusts, 8mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.20 μm/s 
QUICK SUMMARY:

IFO is in NLN and OBSERVING

Calibration sweep was not run this morning due to LLO not being thermalized. TJ plans on running it tomorrow with LLO. 

Otherwise, LHO has been quietyl observing for ~14 hours!

TITLE: 10/11 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 153Mpc
INCOMING OPERATOR: Ibrahim
SHIFT SUMMARY: Locked for almost 14hours. Range has been stable. Public tours came through, but it's been a very quiet shift.
LOG:

• 2212 GRB short E609151

Locked and observing for 9.5 hours. H1 and L1 have moved the calibration sweep to tomorrow since we could not get a coordinated time in today.

Sat Oct 11 10:08:39 2025 INFO: Fill completed in 8min 36secs

TITLE: 10/11 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 154Mpc
OUTGOING OPERATOR: Ryan S
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 6mph Gusts, 2mph 3min avg
    Primary useism: 0.03 μm/s
    Secondary useism: 0.18 μm/s 
QUICK SUMMARY: Locked for almost 5 hours, no alarms, calm environment. Af ew GRB alerts and one lock loss over the night. 

• 0342 GRB short E608872
• 0709 GRB short E608943
• 0709 GRB short E608942
• 0801 Lock loss
• 0944 Observing

TITLE: 10/11 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 150Mpc
INCOMING OPERATOR: Ryan S
SHIFT SUMMARY:

IFO is in NLN and OBSERVING as of 00:38 UTC

After the initial alignment at the start of the shift, IFO locked fully automatically. The wind has also since calmed down. 

LOG:

Closes FAMIS 27427, Last checked in alog 87284

Corner Station looks good - nothing of note

Outstations look good too except for EX, which had a peak on Tuesday. This isn't a problem and is corroborated by Eric's alog 87343, reporting a fan bearing replacement on this fan. Everything has looked quiet since.

Screenshots attached.

TITLE: 10/10 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 151Mpc
INCOMING OPERATOR: Ibrahim
SHIFT SUMMARY:

Started day with high winds peaking at under 40mph at 10amPDT but they never really died.  And then in the early afternoon a huge M7.6 EQ beteween Argentina/Antartica took over most of the afternoon.  Ended the shift starting an Initial Alignment for the hand off to Ibrahim (EQ is steadily dropping, but it's still windy).
LOG:

• 1430-2100 Y-Arm BTE iinspection continues for Y2 (between EY & MY) [randy]
• 1527 Grabbing cardboard & open/close Reciving Door (nellie, kim)
• 1600-1615 optics lab cleaning (nellie)
• 1614-1702 Parts checks in Cheta lab (matt)
• 1701 ISS PD Array (keita,jenny,rahul)
  • 1937 lunch break
  • 2124 Returning to lab
• 1747-1840 Dust Mon FAMIS check on-site (mitch)
• 2049 LOCKLOSS due to M7.6 (see alog 87415)
• 2302 Started an Initial Alignment, but Y-arm has been strugglign to complete....but finally got past Green Arms and on PRC ALIGN!

Ibrahim ran a calibration measurement last night, report attached to this alog (again, the weird bug happened where it pulled the wrong report reference so I had to regenerate). Just from the first page, we can see that the PCAL/GDS transfer function, as measured by both PCAL X and Y, show the uncertainty to be around 1% again. We can see that the modeled actuation strength matches up very well with the current model that has been running since 8/28, indicating that I corrected the drivealign gain properly (ignoring all the mistakes I made in the middle).

The difference in the sensing function is mostly due to the loss of optical gain, this came with the power outage. There might be some small change in the spring, but it is very minimal, and that lines up with the fact that trying to adjust the SRCL offset yesterday only made things worse.

Comparing the GDS/PCAL broadband with previous measurements, we can see that this broadband (in red, Oct 10) is almost exactly the same at the broadband taken on Aug 28 (gray reference) when we pushed this particular calibration. There are small differences at low frequency, perhaps due to some change in the spring behavior of the sensing function, and at high frequency, which I don't have a good immediate reason for.

Given that correcting the TST actuation strength brought the calibration almost exactly back to the model, I spoke with Joe to understand then what the "mysterious" large deviation in the calibration was on Oct 4 (green trace). In the process, I also made a plot comparing the same measurement times, but instead looking at CAL DELTA L/PCAL, so examining what our calibration would look like without TDCFs (I matched the colors with teh GDS/PCAL plot). We determined that by comparing the CAL DELTAL measurement to the GDS measurement, indeed the TDCFs are doing something correctly; without them on Oct 4, our uncertainty woyld be over 6%. However, they are clearly not doing a perfect job of correcting us back to model. Joe thinks that this is because the TCDF correction process may not completely account for the effect of the DARM OLG between each of the actuation TDCF measurement points. We trended what happened to kappa UIM and kappa PUM when I adjusted the L3 drivealign gain to bring kappa TST back to 1 and we see that kappa UIM dropped by 0.9% and kappa PUM by 0.4%. This is happening because the DARM OLG is changing as we adjust kappa TST, and kappa UIM and kappa PUM are seeing some frequency dependent change, but their calculation is assuming that the DARM OLG is not changing.

In summary, the increase calibration uncertainty on Oct 4 is exactly due to the increase in kappa TST, even though the TDCFs were correcting GDS. We can can see by comparing the broadbands from Sept 27 (purple trace) and Oct 4 that at both times the TCDFs were doing an imperfect job of correcting GDS, and that scales with how large the deviation from 1 is; on Sept 27 kappa TST was about 1.02. Now that the actuation strength has been corrected, there is no need to update the calibration at this time.

TITLE: 10/10 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Earthquake
OUTGOING OPERATOR: Corey
CURRENT ENVIRONMENT:
    SEI_ENV state: EARTHQUAKE
    Wind: 31mph Gusts, 22mph 3min avg
    Primary useism: 0.92 μm/s
    Secondary useism: 0.16 μm/s 
QUICK SUMMARY:

IFO is in INITIAL_ALIGNMENT

Recovering from an M7.6 EQ in the Drake Passage ( gap between Argentina and Antarctica). Ground motion is looking good - wind is looking meh.

Plan is to lock, observe and stay that way.

Another big EQ rolling through.  This one is down near Antartica!  Debated when to transition to "ASC Hi Gn", since R-wave was going to be 45-60min.  But S&P waves triggered EQ Mode + saw a yellow Picket Fence---Clicked on ASC Hi Gn button, but during the transition H1 lost lock.  This might have been too big for ASC Hi Gn regardless, but kinda wished I clicked it earlier.

Winds were peaking just under 40mph around the lockloss as well.

Will be hanging out here for a few hours. 

• 2040 Notification of a M7.6 EQ down near Antartica at the Drake Passage
  • R-wave due to arrive in ~1hr and is in the yellow/red area on EQ Response plot (see attached)
• 2043 Start seeing Picket Fence activity (no colors tho)
• 2045 L1 goes down
• 2045 Start seeing S&P Wave spikes on 0.03-0.1Hz Band on nuc5
• 2048 EQ Mode Activated and also get get yellow Picket Fence
• 2049 Turned on Hi Gain ASC
• 2049 H1-LOCKLOSS
• 2050 Keeping ISC LOCK at READY while riding out EQ.
• 2059 Red Picket Fences -AND- SEI_ENV to LARGE_EQ -AND- SEI_CONF goes to LARGE_EQ_NOBRSXY
• 2101 V1 goes down
• 2125 Saw some light BLUE Picket Fences!  (which most likely corresponds with the R-Wave arrival)
• 2135 R-Wave peak (Same or a little bigger than the big Philippines last night). 

Now we wait for R-wave which is probably due to arrive around 2135-ish utc.

[Joan-Rene Merou, Alicia Calafat, Anamaria Effler, Sheila Dwyer, Robert Schofield, Jenne Driggers]

We have looked at the near-30 Hz and near-100 Hz combs (Detchar issue 340) in all of LHO Fscan channels (Full 148 channels list can be found in O4_H1_Fscan_ch_info.yml) to find witnesses and also channels where the amplitude and coherence change at the same dates as DARM.

The list of combs is the following one:


  

    

      
spacing (Hz)
      
offset (Hz)
    
  
  

    
29.9695138888
0
    
99.99845486125
70.02888889
    
99.99845679
0
    
99.99846
29.9694
    
99.9984722225
89.90847222
    
99.99865
0
    
99.99845
10.08992
    
29.96952
520.17208
    
29.9695211
589.9007589
    
29.96951374
760.22840625
  


As reported by Xuanye Fan in Detchar issue 296, "it can be determined that the high-order harmonics disappeared on April 8, 2024, and reappeared on July 7, 2024". Hence, we have compared coherence with DARM in all the channels and the difference between July 1st and July 7th 2024.

Following the findings by Xuanye, we have redone the comb time-evolution plots for all of these combs in order to check for dates where their amplitude changed. As can be seen in the plots below, there are two clear dates where changes in the behavior of the combs took place, April ~4th 2024 and July ~7th 2024. The attached plots to this post are similar to the ones generated by Fscan using FscanFineToothPlot plots, however, they have two differences: They use data from the non-normalized spectras instead of from the time average plots. Additionally, they compute the relative harmonic amplitude with respect to the median of the surrounding 1 Hz spectrogram. The attached plots confirm that there is a significant change in comb amplitude between April 4th and July 7th 2024. One clear example is shown here:



We list here the channels that do show most of these Combs. These same channels do show changes in coherence between July 1st and July 7th 2024, but do not show changes in the amplitude of the combs.

- H1_IMC-F_OUT_DQ
- H1_LSC-MCL_IN1_DQ
- H1_LSC-MICH_IN1_DQ
- H1_LSC-SRCL_IN1_DQ
- H1_PEM-CS_MAG_EBAY_LSCRACK_X_DQ
- H1_PEM-CS_MAG_EBAY_LSCRACK_Y_DQ
- H1_PEM-CS_MAG_EBAY_LSCRACK_Z_DQ
- H1_PEM-CS_MAG_LVEA_INPUTOPTICS_X_DQ
- H1_PEM-CS_MAG_LVEA_INPUTOPTICS_Y_DQ
- H1_PEM-CS_MAG_LVEA_INPUTOPTICS_Z_DQ

In most channels, the comb amplitude tends to get quite low after ~1500 Hz. The following sets of channels show differences between X, Y and Z:

- H1_PEM-CS_MAG_EBAY_SUSRACK_X_DQ (Higher amplitudes and towards higher frequencies)
- H1_PEM-CS_MAG_EBAY_SUSRACK_Y_DQ (Lower comb amplitudes)
- H1_PEM-CS_MAG_EBAY_SUSRACK_Y_DQ (Lower comb amplitudes)

Regarding CS_MAG_LVEA_OUTPUTOPTICS, these combs can be seen best in X, weaker in Y and almost non-existent in Z. (In CS_MAG_LVEA_INPUTOPTICS they look roughly the same height)

- H1_PEM-CS_MAG_LVEA_OUTPUTOPTICS_X_DQ (Strongest)
- H1_PEM-CS_MAG_LVEA_OUTPUTOPTICS_Y_DQ (Weaker lines)
- H1_PEM-CS_MAG_LVEA_OUTPUTOPTICS_Z_DQ (Almost no lines)

Same behavior at:
- H1_PEM-CS_MAG_LVEA_VERTEX_X_DQ (Strongest lines)
- H1_PEM-CS_MAG_LVEA_VERTEX_Y_DQ (Weaker lines)
- H1_PEM-CS_MAG_LVEA_VERTEX_Z_DQ (Almost no lines)

We can see that these combs mostly appear in the corner station. The combs do not appear in neither EX nor EY channels. However, comb 99.99865 Hz offset 0.000 appears in many EX, EY channels and does become more coherent after July 7th. However, it is very close to 100 Hz so it may be influenced by other round-number combs (?)

Fri Oct 10 10:07:47 2025 INFO: Fill completed in 7min 43secs

Gerardo confirmed a good fill curbside.

This is for FAMIS #27398.
Laser Status:
    NPRO output power is 1.857W
    AMP1 output power is 70.67W
    AMP2 output power is 140.3W
    NPRO watchdog is GREEN
    AMP1 watchdog is GREEN
    AMP2 watchdog is GREEN
    PDWD watchdog is GREEN

PMC:
    It has been locked 16 days, 21 hr 4 minutes
    Reflected power = 24.26W
    Transmitted power = 106.6W
    PowerSum = 130.8W

FSS:
    It has been locked for 0 days 1 hr and 35 min
    TPD[V] = 0.538V

ISS:
    The diffracted power is around 3.9%
    Last saturation event was 0 days 3 hours and 40 minutes ago

Possible Issues:
    PMC reflected power is high

We noticed that comparing the last two calibration reports that there has been a significant change in the systematic error, 87295. It's not immediately obvious what the cause of this is. Two current problems we are aware of: there is test mass charge, and kappa TST is up by more than 3%, and we lost another 1% optical gain since the power outage.

One possible source is the SRC detuning changing (not sure how this could happen, but it might change).

Today, I tried to correct some of these issues.

Correcting actuation:

This is pretty straightforward, I measured the DARM OLG and adjusted the L3 DRIVEALIGN gain to bring the UGF back t about 70 Hz, and Kappa TST back to 1. This required about a 3.5% reduction in the drivealign gain, from 88.285 to 85.21. I confirmed that this did the right thing by comparing the DARM OLG to an old reference and watching kappa TST. I updated the guardian with this new gain, SDFed, and changed the standard calibration pydarm ini file to have this new gain. I also remembered to update this gain in the CAL CS model.

Correcting sensing:

Next, Camilla took a sqz data set using FIS at different SRCL offsets, 87387. We did the usual 3 SRCL offset steps, but then we were confused by the results, so we added in a fourth at -450 ct. Part of this measurement requires us to guess how much SRCL detuning each measurement has, so we spent a bunch of time iterating to make our gwinc fit match the data in this plot. I'm still not sure we did it right, but it could also be something else wrong with the model. The linear fit suggests we need about a -435 ct offset. We changed the offset following this result.

Checking the result:

After these changes, Corey ran the usual calibration sweep. The broadband comparison showed some improvement in the calibration. However, the calibration report shows a significant spring in the sensing function. To compare how this looks relative to previous measurements, I plotted the last three sensing function measurements.

The calibration was still with 1% uncertainty on 9/27. On 10/4, the calibration uncertainty increased. Today, we changed the SRCL offset following our SQZ measurement. This plot compares those three times, and includes the digital SRCL offset engaged at the time. I also took the ratio of each measurement with the measurement from 9.27 to highlight the differences. It seems like the difference between the 9/27 and 10/4 calibration cannot be attributed much to a change in the sensing. And clearly, this new SRCL offset makes the sensing function have an even larger spring than before.

Therefore, I concluded that this was a bad change to the offset, and I reverted. Unfortunately, it's too late today to get a new measurement. Since we have changed parameters, we would need a calibration measurement before we could generate a new model to push. Hopefully we can get a good measurement this Saturday. Whatever has changed about the calibration, I don't think it's from the SRCL offset. Also, correcting the L3 actuation strength was useful, but it doesn't account for the discrepancy we are seeing.