Closes FAMIS 26551. Last checked in alog 86515

Laser Status:
    NPRO output power is 1.873W
    AMP1 output power is 70.19W
    AMP2 output power is 141.3W
    NPRO watchdog is GREEN
    AMP1 watchdog is GREEN
    AMP2 watchdog is GREEN
    PDWD watchdog is GREEN

PMC:
    It has been locked 16 days, 0 hr 26 minutes
    Reflected power = 23.93W
    Transmitted power = 105.2W
    PowerSum = 129.1W

FSS:
    It has been locked for 0 days 0 hr and 39 min
    TPD[V] = 0.8058V

ISS:
    The diffracted power is around 4.2%
    Last saturation event was 0 days 0 hours and 39 minutes ago

Possible Issues:
    PMC reflected power is high

Today we pushed calibration report 20250823T183838Z, which updates the calibration model after changes to the actuation (ESD bias change) and sensing (SRC alignment offset change).

These are the steps I took (and two mistakes I made):

• [several days ago] ran pydarm report --regen 20250823T183838Z with the ESD bias and drivealign L3 L2L gains updated in the ini file. I checked to make sure the results were sensible. There is a change in the sensing function at low frequency, probably from an L2A2L related change.
  • note, we checked with the usual sqz "brontosaurus" measurement that the SRCL offset does not need to be updated. Any appreciable spring in the sensing function now is not due to SRC detuning.
• [yesterday] ran pydarm report --regen 20250823T183838Z to get the GDS filters, checked the GDS filters to ensure they looked normal
• [today] ran a broadband PCAL measurement, to get a "before" measurement of the systematic error
  • we had been locked 41 hours at this point, so it's safe to say we were thermalized :)
• committed the report, pydarm commit 20250823T183838Z --valid --message 'new calibration push, new ESD bias and SRC ASC offsets'
• exported the report pydarm export --push 20250823T183838Z
• uploaded, pydarm upload 20250823T183838Z
• restarted gds, pydarm gds restart
  • I marked the GDS restart time as 8:13 local
• waited for GDS to restart
• I was watching the CDS screen for the CALCS model, and once the filter modifications were detected, I reloaded the model, which should load in the appropriate filter changes
• MISTAKE 1: Jeff and I noticed that CAL DELTA L looked very weird and miscalibrated. We realized that the H1:CAL-CS_DARM_FE_ETMX_L3_DRIVEALIGN_L2L_GAIN had not been updated with the new drivealign gain. Once I updated it, CAL DELTA L then looked correct
  • find the screen to check this via sitemap>cal cs>DARM calib> actuation function>ETMX actuator model>L3 drivealign
• Then, I waited and watched the grafana to see when the line monitoring came back online, which a sign that GDS is up and running
• MISTAKE 2: it seemed to be taking a suspiciously long time for grafana to come back online. Joe suggested I check if GDS is available in DTT. It was. I realized I had the grafana page set to "analysis ready" and we were out of observing. Once I switched the setting to "locked", indeed GDS had been back online for 10 minutes at that time.
  • this only delayed the process, but it means we will go over time by a few minutes
• I ran the second broadband, and great success! The systematic error has improved, and is now 2% or less.
• Tony then proceeded to run the simulines measurement.

The attached plot compares the before and after PCAL broadband to GDS CALIB STRAIN. Tony will post the usual alog about the simulines measurement once it is complete.

J. Kissel

After this Tuesday's maintenance day, when I installed the H1 SUS PR3 pitch and yaw estimators (LHO:86578), I'd thought I'd turned them OFF. I'd accidentally left the pitch estimator ON. Whoops! I've turned them OFF this morning -- if only to get some data with *just* the improved SR3 estimators (i.e. that the SR3 pitch estimator now includes longitudinal sus point to M1 contributions; see LHO:86567 and LHO:86589).

The first nominal low noise and subsequent observation segment with SR3 P & Y (P with improved Sus Point L to M1 P contribution) and PR3 P (also with Sus Point L to M1 P contribution includes) was right after maintenance,
    2025-08-26 21:16 UTC,
but really it had been on from 2025-08-26 17:44 UTC.

I turned the PR3 pitch estimator off by 2025-08-28 15:15 UTC.

For reference, assuming everything upstream of the switch is on and functional, you can look at the "use estimator or use OSEM" switch status to check if the estimators are on. The current status is
    H1:SUS-PR3_M1_EST_P_SWITCH_NEXT_CHAN  2.0
    H1:SUS-PR3_M1_EST_Y_SWITCH_NEXT_CHAN  2.0
    H1:SUS-SR3_M1_EST_P_SWITCH_NEXT_CHAN  3.0
    H1:SUS-SR3_M1_EST_Y_SWITCH_NEXT_CHAN  3.0
i.e. (as stated above) the PR3 estimators are OFF = NEXT_CHAN = 2, and the SR3 estimators are ON = NEXT_CHAN = 3.

At superficial glance, i.e. "we've been in nominal low noise observing since they've been on," the IFO doesn't seem to mind AT ALL. And we have a data point of 1.0 that says that we can make it through initial alignment and lock acquisition with it on as well.
We'll post some more quantitative metrics in a bit. 

TITLE: 08/28 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 152Mpc
OUTGOING OPERATOR: Ibrahim
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 5mph Gusts, 3mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.07 μm/s
QUICK SUMMARY:

H1 Has been Locked for 41+ continuous hours without any drops from observing.

Expected drops from Observing:
Today the Comissioning time starts at 1500 -1900 UTC 

Calibration:

• Calibration push 8-8:30
• Simulines measurement 8:30-9

Target of opportunity:

• Try new SRCL FF, Elenna
• Filter cavity backscatter measurement (Sheila, Camilla, ok to be unthermalized)
• Robert:
  •  shaking around LVEA, output arm and other locations to look for location of non linear coupling around peaks 20-50 Hz
  • Injections on BS M0 L,P,Y to mimic motion made by ST2 injections, to check if the coupling is from the optic or the cage
  • End station ground injections with scan of bias, both end stations (and corner)
• DARM offset step with ETMX line Jennie W, make sure it works for longer time next Thursday
• Jim HAM1 injections
• Elenna run MICH Y and SRC2 P/Y 8 Hz injections for sensing calibration
• Jeff, Oli, PR3 estimator tests (in NLN, can be unthermalized)
• + more

TITLE: 08/27 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 156Mpc
INCOMING OPERATOR: Ibrahim
SHIFT SUMMARY:

Smooth and easy shift with H1 locked for 31.75hrs.
LOG:

• 0236 Mongolia M5.3 EQ alert....but does not look bad enough to need ASC High Gain button.

TITLE: 08/27 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 160Mpc
INCOMING OPERATOR: Corey
SHIFT SUMMARY:
GRB-Short E594495 15:35:48 UTC
Vacuum MidX PT 343B Press sensor caused a Verbals Alarm due to phone interfierence with cold cathode gauge. @ 20:44 UTC
Vac Team said this may take a few days to start working properly again, so it may be red for a while.

SuperEvent S250827fo candidate @ 22:50 UTC !!

H1 has been Locked and Observing for 25+ hours.

LOG:                                                                                         

TITLE: 08/27 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 156Mpc
OUTGOING OPERATOR: Tony
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 7mph Gusts, 4mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.06 μm/s
QUICK SUMMARY:

H1's been locked for almost 26.5hrs.  Environmentally, microseism is low, as well as low winds, and there was recently some light rain!

Sheila, Tony, Camilla

Sheila and Tony noticed that we had a ~30 minute 10MPc range drop last night with related extra low-freq glitches, from the range BLRMs this is most clear in th 20-34Hz band. This noise is broadband 15-100Hz  looking at DARM, plot. And trending the common range drop channels form last year, plot, we see a slight increase in FC2_M3_NOISEMON, plot, confirmed as the cause by the dtt spectrum. Sheila is proposes the cause could be FC backscatter into the IFO. There is no increase in FC1 noise apart from small regions at 80Hz, 160Hz, 190Hz, plot.

There is slighly more noise 8-20Hz in HAM8 in the low range time and 3 peaks at 7-9Hz are gone, plot.

Wed Aug 27 10:09:46 2025 INFO: Fill completed in 9min 43secs

Joe B, Elenna

Since the ETMX ESD bias was changed, kappa TST has been trending upwards. This could be due to charging. Kappa TST has increased nearly 3%.

The following packages were added to the default CDS Conda environment on workstations.

- hws (Hartmann Wavefront Sensor)

- epics-striptool

- mypy, a linter and type checker for python programs

TITLE: 08/27 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 150Mpc
OUTGOING OPERATOR: Oli
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 6mph Gusts, 4mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.08 μm/s
QUICK SUMMARY:
H1 Has been Locked in Nominal Low Noise for 17.5 + hours.
All Sub Systems seem to be running well.

 

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.

DriptaB, TonyS, RickS

Similar to alog 86227, the BTRP adapter flange and GV were installed on Tuesday at the MY station.  Leak checking was completed today with no signal seen above the ~e-12 torrL/s background of the leak detector.  

Pumping on this volume will continue until next Tuesday, so some additional noise may be seen by DetChar.  This volume is valved out of the main volume, so the pressure readings from the PT-243 gauges can be ignored until further notice.  

Yesterday, we installed the BTRP (Beam Tube Roughing Pump) adapter flange on the 13.25" gate valve just to the -X side of GV13.  This included installing a 8" GV onto the roughing pump port of the adapter, moving the existing gauge tree onto the new adapter, and installing a 2.75" blank on an unused port.  All of the new CF joints were helium leak tested and no signal was seen above the ~9e-11 torrL/s background of the leak detector. 

The assembly is currently valved out of the BT vacuum volume via the 13.25" GV, and is being pumped down via small turbo and aux cart.  Therefore, the PT-343 gauge reading is only reporting on the BTRP assembly pressure, not the main BT pressure, so it can be ignored until further notice of it being vavled back in.  This system has been pumping via aux cart or leak detector since ~2pm yesterday, and will continue to be pumped until it is in the pressure range of the BT volume.  The aux cart is isolated by foam under the wheels, but some noise may be noticed by DetChar folks, hence the DetChar tag on this report.

Andrei, Naoki, Sheila

Following the research of aLOG 78125 and aLOG 78262, we aimed to quantify the value of backscattering from the ZM2 and ZM5. We performed backscattering measurements under the assumption that modulation of the optical path between scatterer and interferometer would introduce additional noise in the DCPD spectrum [1-4].

We used data from the H1:OMC-DCPD_SUM_OUT_DQ channel (calibrated to mA of photocurrent) for the times of aLOG 78125. We've then calculated RIN with correction for the DARM control loop. Using Eq. 25 from [1], we performed manual fit. Although we couldn’t perfectly fit within the range from 15 Hz to 21 Hz (probably because of the chosen Welch's transform parameters), we were still able to obtain meaningful results for the backscattering coefficients (see Fig. Backscattering_meas.png). The resulting coefficients are below:

r_ZM5 ≈ 4 x 10^-4

r_ZM2 ≈ 0.1 x 10^-4

Also note, that the amplitude of the excitation used for fit is several times larger than that we've measured from the H1:SUS-ZM#_M1_DAMP_L_INMON channel (1.2 μm unstead of 0.4 μm).

Code that was used for this calculation is attached to this report. OM1_fringewrapping_test.m (Sheila's code) was used to calculate RIN, main.nb was used for manual fit and plotting.

[1] Martynov, D. V., Hall, E. D., Abbott, B. P., Abbott, R., Abbott, T. D., Adams, C., ... & McIver, J. (2016). The sensitivity of the Advanced LIGO detectors at the beginning of gravitational wave astronomy. Physical Review D, 93(11), 112004.

[2] Ottaway, D. J., Fritschel, P., & Waldman, S. J. (2012). Impact of upconverted scattered light on advanced interferometric gravitational wave detectors. Optics express, 20(8), 8329-8336.

[3] Nguyen, P., Schofield, R. M. S., Effler, A., Austin, C., Adya, V., Ball, M., ... & Moreno, G. (2021). Environmental noise in advanced LIGO detectors. Classical and Quantum Gravity, 38(14), 145001.

[4] Fricke, T. T. (2011). Homodyne detection for laser-interferometric gravitational wave detectors. Louisiana State University and Agricultural & Mechanical College.