TITLE: 07/27 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 155Mpc
OUTGOING OPERATOR: Ibrahim
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 15mph Gusts, 8mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.05 μm/s
QUICK SUMMARY:

H1 has been locked 3.5+hrs.  Environmetnally, pretty quiet after the big afternoon EQ; winds are dropping, µSeism is low (touching the bottom of the screen!).

There is a question of To Run Or Not Run a calibration.  H1 is now thermalized (and a recent Short GRB standdown time Ibrahim had has expired).  Reached out to LLO, but I'm guessing they are on Autopilot for the night.  Ibrahim through out the idea of a calibration, and I think we'll just keep an eye on L1---if they lose lock, will run one.  (Or we can wait to coordinate a Calibration tomorrow.)

TITLE: 07/26 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 153Mpc
INCOMING OPERATOR: Corey
SHIFT SUMMARY:

IFO is in NLN and OBSERVING 19:53 UTC (4 hr lock!)

IFO was very well behaved (2 days in a row!). Fully auto locks. Lost lock once due to a 6.6 EQ but managed to recover NLN within 2.5 hours. Lockloss alog 85997.

LOG:

None

Earthquake cause Lockloss ending 20hr 45 minute lock. It was a 6.6 EQ from NZ.

TITLE: 07/25 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 152Mpc
INCOMING OPERATOR: Oli
SHIFT SUMMARY:

H1 was locked the entire shift even with the winds which topped around 35mph.  H1's been locked just over 8.25hrs.
LOG:

• 2340 Erik brought back the PIMON window on nuc25 (it had died earlier this week and CDS has been monitoring and will see how it does for the next lockloss).
• 0040-0120 Fire was spotted to the north, across the Columbia, and beyond the White Bluffs (Tony & then Jennie notified the Control Room as they were leaving site).  Richard & Mike were notified via text.

Sat Jul 26 10:10:12 2025 INFO: Fill completed in 10min 8secs

TITLE: 07/26 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: 10mph Gusts, 5mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.04 μm/s
QUICK SUMMARY:

IFO is in NLN and OBSERVING since Jul 25 20:44 UTC (18 hr lock!)

IFO is still locked from yesterday, with consistent range.

As part of the DQ shift, I was looking at the DARM spectrorams to identify non-stationary (of the order of hours) features. Below is a list of features that were relatively obvious from the spectrograms. I used GDS-CALIB_STRAIN_NOLINES channel data for July, 21, 2025. In order to see the frequency variations a bit clear, i used 100-second spectrograms.

• 17.8 Hz, wandering line with variation around 0.2 Hz
• 20.26 Hz with linewidth/variation of ~ 0.04 Hz 
  • This was also reported in the a-log 85856 recently. In addition to the narrow line, sometimes we also see ~1 Hz broad noise around the narrow line. It is not clear whether thest two features (narrow and broad) are related.  
• 25.6 Hz with ~0.2 Hz wander
• 27.1 Hz with ~0.1 Hz wander
• 33.0 Hz with ~0.2 Hz wander
• 40.1 Hz with linewidth/variation of ~ 0.02 Hz
  • Is this a harmonic of 20.26? Their temporal behaviour look similar. 
  • The bruco results show that most of the low frequency features listed above including 20.26 Hz come from the input part of the IFO such as HAM2-3, IMC, which was also reported in the a-log 85959. Further studies required to identify the exact coupling location and the mechanism.
• 126.24 Hz with linewidth/variation of ~ 0.02 Hz
• 136.36 Hz with linewidth/variation of ~ 0.02 Hz
• 151.48 Hz with linewidth/variation of ~ 0.02 Hz
  • All the three lines (126.24 Hz, 136.36 Hz, and 151.48 Hz) look similar in their variations over time and looking at the time scales the variations may be related to temperature; not sure if the source is the same for all three frequencies.
• 177.1 Hz with variation of 0.2 Hz
• 179.1 Hz with variation of 0.1 Hz
  • The temporal variations of 177.1 Hz and 179.1 Hz look similar. 
• 272.65 Hz with 0.2 Hz variation
  • Its variation looks similar to 126.24 Hz, 136.36 Hz, and 151.48 Hz (the frequency is very close to the next harmonic of 136.36 Hz)
• 540 Hz with 0.5 Hz width; excess noise at the beginning of the lock (input jitter?)
• 660 Hz with 1 Hz width; excess noise at the beginning of the lock (input jitter?)
  • We see something similar in LLO (alog 77265)also.
• 3073 Hz with ~2 Hz frequency ring down
• 3131 Hz with ~2 Hz frequency ring down
  • The 3073 Hz and 3131 Hz features look similar (the frequency of the feature decreases over time after the lock). Maybe down conversion of HOMs?
• 6556.8 Hz with 0.02 Hz variation
  • This one looks a bit different from 3131 Hz and 3073 Hz. It has more stable slope and small frequency variation. Maybe this is also realted to HOM, but one with high Q?

Both BRS x & y are within their nominal regions and mostly flat over the last couple months.  CLOSING FAMIS 26457.

TITLE: 07/25 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 153Mpc
OUTGOING OPERATOR: Ibrahim
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 12mph Gusts, 5mph 3min avg
    Primary useism: 0.03 μm/s
    Secondary useism: 0.05 μm/s
QUICK SUMMARY:

Very easy and nice transition hand-off from Ibrahim.  H1 has been locked quite a bit since the big EQ 25hrs ago.  (The forecasts note winds picking up from 6-10pm locally, so we'll be watching for that!)

TITLE: 07/25 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 154Mpc
INCOMING OPERATOR: Corey
SHIFT SUMMARY:

IFO is in NLN and OBSERVING as of 20:44 UTC (2 hr 50 min lock)

H1 has been very well behaved and required 0 operator intervention (other than the standard TLC).

One Lockloss (Lockloss alog 85989)

LOG:

None

For FAMIS #26410: There is a notable step in most channels, but this corresponds to Tues Maintenance (922amPDT), but other than that, all trends are atleast flat FWIW.

Unknown cause lockloss. Lockloss tool flags the wind but given gusts are generally under 20mph, this is unlikely. IFO is at MOVE_SPOTS now after doing an initial alignment. Everything automatic so far.

..

Using my model for the propagation from OM2 to the OMC I discussed in alog #84255, I made a contour plot for the mode overlap (O(q₁,q₂ ))_c between the mode propagated through cold OM2 to the OMC, q₁ and the fundamental mode of the OMC, q₂ divided by the mode propagated through hot OM2 overlapped with the OMC mode, (O(q₁,q₂ ))_h .

This is so I could comnpare it to measurements I made of the drop in optical gain, G when the curvature of OM2 was changed. Its hard to predict how much loss in total there is with the full interferomter locked but the optical gain change can tell us the change in optical loss between these two states which we assume to be due to mode-mis-match.

O^' / O = (G^' / G)²

In the plot I have used overlap ratio percentage, O % on the z axis, the real part of of the q I started with between OM1 and OM2 on the x-axis, and the imaginary part of this q on the y-axis.

O % = (O(q₁,q₂ ))_h / (O(q₁,q₂ ))_c × 100

The white line gives the square ratio of the optical gains measured in full-lock (alog #82559) for each of these states. The code to run this is in OM2_to_OMC_comp_full_IFO.m found at this respository on ligo gitlab.

The white line contains a contour of possible values of the q parameter between OM1 and OM2 for the full-locked state of the interferometer bar any changes since the end of January 2025 when I took these measurements.

Fri Jul 25 10:09:47 2025 INFO: Fill completed in 9min 43secs

TITLE: 07/25 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: 4mph Gusts, 2mph 3min avg
    Primary useism: 0.03 μm/s
    Secondary useism: 0.06 μm/s
QUICK SUMMARY:

IFO is in NLN and OBSERVING as of 10:38 UTC (4 hr lock)

H1 survived 2 strong earthquakes (5.7 and 6.2) near NZ.

TITLE: 07/25 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 151Mpc
INCOMING OPERATOR: Oli
SHIFT SUMMARY: We had an early evening full of Earthquakes, a lockloss from an ETMX glitch then a double candidate detection at the end of the shift.
LOG:

• 22:50 - 00:45 UTC earthquake mode, we held in down. A 6.1 & a 5.8 from eastern Russia then while we were ringing down a 6.6 from north of New Zealand.
  • 00:00 UTC While we were down Fil went and swapped out the sat box at EX for TMSX alog85980.
  • 00:46 - 01:05 UTC Initial alignment
  • 01:52 UTC GRB-Short E583596
• 02:18 UTC lockloss from an ETMX glitch
  • 03:24 UTC Observing
  • 04:09 UTC Superevent S250725j
  • 04:21 UTC Superevent S250725l

02:18 UTC lockloss after only 27 minutes, looks like an ETMX glitch.

M. Todd, E. Capote, C. Compton, S. Dwyer

After the vent, beam profiles were taken at REFL and POP (single-bounce) which are of interest to modeling efforts to gain some confidence in model parameters. Using a-la-mode to model the beam throughout the IFO and compare it to the measurements, we are able to confirm most of the parameters in the finesse yamlfile for the IFO model. See Figure 1 and Figure 2 for measured profiles of REFL and POP compared to the model beam parameters.

Now that we have more confidence in the model, we feel more comfortable looking at figures of merit that the model can provide -- such as the beam overlaps of different modes. Of particular interest was the input beam overlap with the PRC and ARM eigenmodes -- it seems the input beam is not super well mode-matched the PRC.

There are plenty of interesting figures of merit that we can calculate using this model that help us understand more about the mode-matching state of our interferometer, and hopefully inform steps to correct mismatch.

The code used in this modeling is held in the 'ligo-commissioning-modeling' repo folder: