Thu Aug 07 10:07:03 2025 INFO: Fill completed in 6min 59secs

Lockloss at 2025-08-07 16:15UTC after 5.5 hours Locked due to some fast tractoring it's looking like an ETMX glitch :(

Ran our usual calibration measurements this morning following the wiki instructions. We plan to make some bias changes and then run this again. I'll comment to this log with that info.

Simulines start:

PDT: 2025-08-07 08:36:03.467961 PDT
UTC: 2025-08-07 15:36:03.467961 UTC
GPS: 1438616181.467961

Simulines end:

PDT: 2025-08-07 08:59:22.221768 PDT
UTC: 2025-08-07 15:59:22.221768 UTC
GPS: 1438617580.221768

Files:

2025-08-07 15:59:22,060 | INFO | File written out to: /ligo/groups/cal/H1/measurements/DARMOLG_SS/DARMOLG_SS_
20250807T153604Z.hdf5
2025-08-07 15:59:22,068 | INFO | File written out to: /ligo/groups/cal/H1/measurements/PCALY2DARM_SS/PCALY2DA
RM_SS_20250807T153604Z.hdf5
2025-08-07 15:59:22,072 | INFO | File written out to: /ligo/groups/cal/H1/measurements/SUSETMX_L1_SS/SUSETMX_
L1_SS_20250807T153604Z.hdf5
2025-08-07 15:59:22,077 | INFO | File written out to: /ligo/groups/cal/H1/measurements/SUSETMX_L2_SS/SUSETMX_
L2_SS_20250807T153604Z.hdf5
2025-08-07 15:59:22,081 | INFO | File written out to: /ligo/groups/cal/H1/measurements/SUSETMX_L3_SS/SUSETMX_
L3_SS_20250807T153604Z.hdf5
 

1438590708

The lock loss that we had over night was unfortunately an ETMX glitch. We hadn't seen one since changing the ETMX bias July 28th so we were hopeful that it was the fix. Sad.

TITLE: 08/07 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 144Mpc
OUTGOING OPERATOR: Ryan C
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 5mph Gusts, 1mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.08 μm/s
QUICK SUMMARY: Locked for almost 4 hours. Had a GRB (E587865) short come through at 1046UTC just a few minutes after we got to observing. Plan for today is commissioning and calibration from 1530-1900UTC.

TITLE: 08/07 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 151Mpc
INCOMING OPERATOR: Ryan C
SHIFT SUMMARY:

IFO is in NLN and OBSERVING since Aug 5 22:22 UTC (30 hr 40 min lock!)

Nothing to add other than well done everyone (particularly comissioners) for contributing to such a stable IFO state - this is definitely the O4c record so far.

LOG:

None

Ivey,

I finished the yaw-to-yaw transfer functions for the OSEM estimator using the corrected measurements that Oli took for SR3 yesterday [see LHO: 86202].

The fits were added to the Sus SVN and live inside '~/SusSVN/sus/trunk/HLTS/Common/FilterDesign/Estimator/fits_H1SR3_2025-08-05.mat'. They are already calibrated to work on the filter banks for the estimator and can be installed using 'make_SR3_yaw_model.m', which is in the same folder.

Attached below are two images of the fits for the estimator.

The first attachment shows the Suspoint Y to M1 DAMP Y fit. The zpk for this fit is

'zpk([0,0,-0.027+20.489i,-0.064+11.458i,-0.027-20.489i,-0.064-11.458i],[-0.072+6.395i,-0.072-6.395i,-0.096+14.454i,-0.096-14.454i,-0.062+21.267i,-0.062-21.267i],-0.001)'

The first attachment shows the Suspoint Y to M1 DAMP Y fit. The zpk for this fit is

'zpk([-0.002+19.224i,-0.007+8.31i,-0.002-19.224i,-0.007-8.31i],[-0.06+6.398i,-0.06-6.398i,-0.091+14.439i,-0.091-14.439i,-0.074+21.29i,-0.074-21.29i],12.184)'

TITLE: 08/06 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 147Mpc
INCOMING OPERATOR: Ibrahim
SHIFT SUMMARY: Very quiet day with H1 observing throughout except for just a few minutes this morning. H1 has now been locked for over 25 hours.
LOG:

• 15:34 - Dropped observing from SQZ PMC volts railing
• 15:38 - Observing

TITLE: 08/06 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 151Mpc
OUTGOING OPERATOR: Ryan S
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 19mph Gusts, 14mph 3min avg
    Primary useism: 0.07 μm/s
    Secondary useism: 0.11 μm/s
QUICK SUMMARY:

IFO is in NLN and OBSERVING as of 22:22 UTC (24hr 45 minute lock)!

IFO continues to be very well behaved. Nothing of note.

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.

DQ Shifters: Riley McNeil and Emil Lofquist-Fabris.

• Daily observing duty cycle: 57.91%, 38.96%, 38.57%, 51.84%, 53.67%, 89.90%, 55.83%. Week average: 55.24% Observing.

• This week was plagued by earthquakes, most notably the 8.8 magnitude earthquake from Russia and its subsequent aftershocks.

  • These really hindered the duty cycle of the detector.

  • The elevated ground motion in the earthquake band appears to be related to light scattering just above 20 Hz.

• BNS range was consistently around 150-155 Mpc throughout the week, with 1 exception being on Sunday, when the detector ran without the squeezer for 2 and a half hours, dropping the range by about 15 Mpc.

• There were also multiple days where the SQZ had issues staying locked, causing the detector to drop out of observing.

• Throughout the shift there has been recurring glitching/noise in the 20-40 Hz range, seen both in the glitch and strain plots. However, they were less significant in the last two days.

  • This has been seen in previous shifts, however relatively inconsistently.

• There was a recurring spike in noise in the H1 Y-manifold beam tube motion [X] at the exact same time every day this week (right after 17:00)

• For the first 4 days of the shift, there was a recurring noise from ~11:00-13:00 in the corner station accelerometers (all degrees of freedom), however starting Friday it stopped showing up.

• There was a low chi-squared PyCBC trigger that appears to be a blip, with the new SNR being the same as its original SNR on August 2.

See the full report here: https://wiki.ligo.org/DetChar/DataQuality/DQShiftLHO20250728

19:50 UTC

While I was trying to damp the highest modes, the pair around 1008 on ETMX (newish modes that were discovered in 2023 alog68650) which have been above 10^-16 on DARM I noticed that the other pair from ETMY (16 & 17) were not being monitored. I went into SUSPROC and unmonitored FM1, and the gain for the BL and RMSLP banks for EY 16 & 17, I turned on FM1 then ramped up the gains  starting with BL then RMSLP, then I accepted and remonitored them all.

State of H1: Observing at 150Mpc

Quiet morning with H1 staying locked throughout; current lock stretch is almost up to 21 hours. There was one brief drop from observing at 15:34 UTC when the SQZ PMC unlocked, but everything recovered automatically and H1 resumed observing a few minutes later.

Oli, Ivey, Edgard.

We used Oli's measurements from [LHO: 86204] to do an OSEM calibration for the PR3 M1 OSEMs. Here are the outputs of the calibration script.
_______________________________________

OSEM calibration of H1:SUS-PR3
Stage: M1
2025-08-05_1700 (UTC).

The suggested (calibrated) M1 OSEMINF gains are
(new T1) = 1.770 * (old T1) = 2.055
(new T2) = 1.547 * (old T2) = 1.544
(new T3) = 1.443 * (old T3) = 1.511
(new LF) = 1.590 * (old LF) = 1.862
(new RT) = 1.774 * (old RT) = 2.063
(new SD) = 1.543 * (old SD) = 1.639

To compensate for the OSEM gain changes, we estimate that the H1:SUS-PR3_M1_DAMP loops must be changed by factors of:
L gain = 0.596 * (old L gain)
T gain = 0.648 * (old T gain)
V gain = 0.617 * (old V gain)
R gain = 0.617 * (old R gain)
P gain = 0.670 * (old P gain)
Y gain = 0.596 * (old Y gain)

The calibration will change the apparent alignment of the suspension as seen by the at the M1 OSEMs
NOTE: The actual alignment of the suspension will NOT change as a result of the calibration process

The changes are computed as (osem2eul) * gain * inv(osem2eul).
Using the alignments from 2025-08-05_1700 (UTC) as a reference, the new apparent alingments are:

DOF        Previous value       New value            Apparent change
---------------------------------------------------------------------------------
L          -57.1 um             -33.6 um               +23.5 um
T          -101.3 um            -65.6 um               +35.7 um
V           62.4 um              36.6 um               -25.8 um
R           433.5 urad           225.7 urad          -207.8 urad
P          -631.8 urad          -406.5 urad          +225.2 urad
Y          -166.7 urad          -76.1 urad           +90.5 urad

We have estimated a OSEM calibration of H1 PR3 M1 using HAM2 ST1 drives from 2025-05-21_0000 (UTC).
We fit the response M1_DAMP/HAM2_SUSPOINT between 5 and 15 Hz to get a calibration in [OSEM m]/[GS13 m]

This message was generated automatically by OSEM_calibration_SR3.py on 2025-08-06 01:07:57.985744+00:00 UTC

%%%%%%%%%%%%%%%%%%%%%%%%%%%%

EXTRA INFORMATION

The H1:SUS-PR3_M1_OSEMINF gains at the time of measurement were:
(old) T1: 1.161
(old) T2: 0.998
(old) T3: 1.047
(old) LF: 1.171
(old) RT: 1.163
(old) SD: 1.062

The matrix to convert from the old Euler dofs to the (calibrated) new Euler dofs is:

+0.596    -0.0    +0.0    -0.0    +0.0    -0.003
+0.0    +0.648    -0.0    +0.0    +0.0    -0.0
-0.0    +0.0    +0.617    -0.004    +0.001    +0.0
+0.0    +0.0    -0.748    +0.617    -0.007    -0.0
+0.0    +0.0    +0.517    -0.036    +0.67    -0.0
-0.407    +0.0    -0.0    +0.0    -0.0    +0.596

The matrix is used as (M) * (old EUL dof) = (new EUL dof)
The dof ordering is ('L', 'T', 'V', 'R', 'P', 'Y')

I posted LHO:81917 regarding the calibrated ASC coupling functions. At the time, my results seemed wildly large and I was certain I had made some calibration error somewhere, and indeed I had. Lee reached out last week since he is working on something similar for his optimal controls work, see LLO:77901. These are the calibration errors I made:

• my old calibration for PUM: 20 V /2**20 ct [DAC] * 0.268 mA / V [drive strength] * 0.0309 N / A [force coeff] * 70.7 mm [lever arm]
  • the bolded term is technically correct because we do have a 20 bit DAC, however, there is a sneaky factor of 4 gain filter in the coil output filters bank, which was added to avoid everything changing by a factor of 4 when the DACs were upgraded from 18 bit to 20 bit
• There is an additional euler to osem gain value of 3.5355, and factor of 4 for four coils

The full counts of drive to Nm of torque conversion factor is therefore: (20 / 2**20) * 0.268e-3 * 0.0309 * 70.7e-3 * 4 * 3.5355 * 4 = 6.317e-10 Nm/ct

Lee also pointed out instead of using the modeled free suspension plant, I should be using the radiation pressure modified plant. This is correct, however for the purposes of calibrating the coupling function the effect is mostly the same, since we know that the rad/Nm transfer function is the same at 10 Hz within a few percent for zero power and high power.

However, for completeness, and because it matters for other calibrations, I did this instead:

• Gabriele fitted HARD loop OLGs to determine the hard plants at high power in 77857 and 71848. These fits are in counts, so they need to be scaled to real units
• Using the same modeled free plants, in T2300299, I scaled the high power plant to the modeled plant at 20 Hz
• I used this scaled high power plant to calibrate the m (DARM)/Nm (ASC) coupling function to m (DARM)/ rad (ASC)

The end result is much more sensible, resulting in a coupling function around 30 Hz that is about 1 mm/rad for both pitch and yaw. This is still "high" in the sense that Matt and Lisa assumed a coupling on the order of 0.1 mm/rad in T0900511.

I went a step further to check the linearity of the coupling. I measured the transfer function of ASC to DARM during the noise budget injection times. However, the noise budget is usually calculated with an excess power projection, so we have both quiet and injection times taken. Using the same calibration method, I compare the excess power coupling function with the linear transfer function coupling function. They appear to be nearly the same, showing that the ASC coupling is dominated by linear behavior.

Today, Sheila and I decided to increase the ETMX ESD bias voltage. We would like to operate at a higher bias for a short period to see if the extra actuation range allows us to survive the ETMX glitch locklosses. However, we also wanted to understand what effect this has on our range.

Sheila made small steps to increase the ETMX bias voltage and adjusted the L3 drivealign gain accordingly. After every step, I measured the DARM open loop gain and we adjusted the drivealign gain further to maintain the DARM UGF. Once we doubled the voltage, we further adjusted the drivealign gain to bring kappa TST to one. It's important to note that we saw that the correction factor required to maintain the UGF (at 70 Hz) was slightly different than the correction factor required to bring kappa TST back to 1 (measured at 17.6 Hz).

We took a PCAL broadband measurement at the regular and double bias configurations (documented here). Even with kappa TST near 1, there was a small frequency-dependent difference between the two measurements.

Sheila then took us back and forth from the double bias to regular bias states so we could get some noise comparison times to determine if the noise is worse with double bias.

I exported the PCAL broadband injections and used them to calibration GDS strain for the four times above into PCAL meters. The noise from 15-400 Hz looks to be the same for each time, so I don't think there will be a significant impact to the sensitivity if we double the bias.

I ran a linear regression fit on the voltage and drivealign data from our steps, using this document as reference. I was able to fit alpha - gamma (slope) and the beta values (y-intercept). I calculate alpha - gamma = 9.14e-10 N/V^2 and beta - beta2 = -4.08e-8 N/V

We are planning to go to this double bias for some time to see if reduces the number of ETMX glitch locklosses.