[Sheila, Louis, with input from others in CR]

It was suggested that it would be good to check 1.) the beam spot position on PR2 and 2.) determine if we are still at the O4 PR2 beam spot and if we are not, how far off we've moved due to all the recent input alignment changes.

Yesterday, we tried to measure the beam spot position on PR2 using the typical A2L dither approach. We did the same exercise recently on MC2 (91420). I placed an 8.125 Hz dither in PR2's M3 DITHER bank in pit and yaw and adjusted the corresponding A2L gains to minimize PRCL_OUT / DITHER_IN. We have some doubts about the validity of these measurements as we had some issues with the TF magnitude drifting around and taking a while to stabilize. We also had some issues with reproducibility during the same session. This may need to be redone with higher injection amplitudes. Another confusing feature is that, while both the PIT and YAW measurements experienced a sign flip as we moved through the gain steps, some TF measurements had phases that were not fully flipped by 180 deg. Not sure if this is an SNR issue. 

O4 A2L gains: I confirmed that the A2L gains in place at the start of the test are the O4 gains. They've been unchanged since mid-O4. These gains are: 

P2L: -0.36
Y2L: +0.15

Based on the calculations by Koji referenced in 42600 and 42601, the O4 beam spot position on PR2 is offset from the center of the optic by -0.675 mm in PIT and +0.281 in YAW (pit dtt, yaw dtt, interp). I updated Jenne's CalcSpotPos.py script (77443) to use the corrected coil force imbalance factor (alpha) to mm relationship. This script calculates the beam offset position in mm based on the a2l gains using Koji's calculations. The script lives at: /opt/rtcds/userapps/trunk/isc/common/scripts/decoup/BeamPosition/CalcSpotPos.py.

Yesterday's measurements give:

P2L: -0.60
Y2L: +0.52

which translates to -1.125 mm in PIT and +0.975 mm in YAW from the center. The fact that we were able to find another position on PR2 that minimizes A2L coupling suggests that we are not at the O4 beam spot position on PR2. The estimated delta from the O4 position on PR2 to now is: -0.24 mm in PIT and +0.37 mm in YAW.


The dtt templates I used are my home directory under Templates/pr2_a2l_pit.xml and Templates/pr2_a2l_yaw.xml. The 8.125 Hz injection was placed via awggui.

WP 13562

Documented the wiring for the OMC PZT Driver. Unit installed is S1301298.

Installed boards:
High Voltage D060283 Board - output going to Rear DB25 Pins 1 & 14
Low Voltage D1300024 Board - output going to Rear DB25 Pins 2 & 15

Spare unit S1301298 has different configuration.

The older 3 electrode EOM has been taken apart and reassembled as part of the crystal crisis a few months back. The attached plot shows a sweep of the the reflected RF power using the 45MHz input. The resonance is still close to 45.5MHz, where we would expect it. The 43MHz needed for JAC is pretty far off resonance, also as expected. This should be no worth than what we have installed assuming the Qs are similar.

dcc of old tests: E1300758

J. Kissel, J. Wright
WP:13564

We're continuing to move forward with making sense of the H1SPIH23 QPD calibration, and are craving a place to store the calibration into ISI displacement that's after the conversion to normalized spot displacement (QPD_{A,B}_{PIT,YAW} banks) but before the decoupling matrix that converts the QPD basis into the ISI basis (QPD2CART). Here's the model prep for installing 4 new filter banks (QPD_{A,B}_{PIT,YAW}_CAL) upstream of the matrix, and storing the output into the frames at 2048 [Hz].

Screenshot #1: The new blocks in the SPI_LIBRARY > HJK > OL block.
Screenshot #2: Adding the new channels in the DAQ channel list at the SPI_LIBRARY > HJK level.
Screenshot #3: Visual aide showing the QPD portion of the SPI overview screen, prior to installing these changes.
Screenshot #4: Visual aide showing the MEDM infrastructure prior to this model change.

"Why don't you just put the calibration in the QPD_{A,B}_{PIT,YAW} banks?" Because we don't want to lose the usual visual aide of the normalized spot position XY scatter plot that shows the centering of the QPD as everyone is used to seeing it.
"Why don't you put the calibration in the ISIOUTF banks?" We're anticipating the need to put some sort of "normalizing" gain that's tailored to the individual ISI, and some anti-aliasing filters in this bank, so we want to keep these conceptually different.

Library part changed committed to userapps/spi/common/models/SPI_LIBRARY.mdl as of rev r35940. The model change has been successfully test compiled on the h1build machine.

J. Kissel, E. Capote
ECR:E1800188 / IIET:10921
WP:13555

Pushing forward with a long-standing "to-do" signal exchange between ASC and SUS, here's the front-end software model prep for piping ISC "QPDs" (the audio-frequency channel outputs of the wave-front sensors of the same name),
    - REFL_A_DC (measuring the reflection off of PRM and the return beam from the IFO), 
    - POP_A_DC (measuring the transmission through PR2, and the forward beam into the PRC)
    - POP_X_DC (also transmitted through PR2, but measuring the return beam from the IFO)
    - AS_C (measuring the output from SRM, the output of the IFO) [this is the only one that's actually "just" a QPD]
into the recycling cavity HSTSs, i.e. PRM, PR2, SR2, and SRM's already-present lock-in infrastructure as possible signals for demodulation. As motivated fully in the ECR, the primary reason is that unlike QUADs, the BS, and HLTSs, the HSTS's don't have optical levers. As such, length-to-angle characterization of the suspensions has been limited to the M3-stage OSEMs, which are not accurate to the level needed for, e.g. coil actuator balancing (methods described in LHO aLOGs 11392 and 9453). Using the IFO beam, and some linear combination of the four signals should give us excellent lever arms for angular sensing of each HSTS's motion, but better than the M3 OSEMs. Again, there're more reasons to do this than just coil balancing; see ECR.

Here're the changes:

h1asc model (committed to r35935)
    (1) Screenshot #1 Added pick-off and top-level output bubbles to REFL_A_DC PIT/YAW, POP_A_DC PIT/YAW, POP_X_DC signals. AS_C already has them. In the process of doing this, I cleaned up the use of output bubbles vs. gototags; now all the above mentioned QPDs that are sent to the top level are done in a segregated group, taking advantage of the goto-tags rather than ramming the output bubbles in as pick-offs right next to the output of the signal processing block.

    (2) Screenshot #2 and Screenshot #2 At the top level, add PCIE dolphin IPC senders for these signals to broadcast them out onto the dolphin fabric for anyone to consume. AS_C already had *shared memory* IPC for consumption by the SQZ alignment system, but Dolphin PCIE senders are needed to get them to SUS.

RC_MASTER library (committed to r35939)
    Screenshot #4 Expanded the options as SIG input the LKIN_P and LKIN_Y demod blocks to include the QPDs, with the M3 OSEMs and the 4 QPDs as the 5 inputs to a 5x1 matrix. Those new input bubbles create to input ports to the library part that appears at the top level of each individual suspensions' top level model. I intentionally chose to have the inputs be in the middle of the list of inputs so that signals group better at the top level. This has the consequence of needing to redo the top-level connections in the all the instantiations, but I'll be in there already and I'm willing to take the extra five minutes per model now in order to have a more legible model for the next 3 years. The input is then fed into some input filtering in case that's needed. the banks resolve with channel names like H1:SUS-PRM_M3_QPDINF_P_REFL_A_IN1.

Top level of h1susprm, h1suspr2, h1sussr2, and h1sussrm (committed to r35937)
    (1) Re-sized and re-connected the inputs to the RC_MASTER library to account for the 8x new inputs in the middle of the block.
    
    (2) Installed Dolphin PCIE IPC receivers that match the senders in the h1asc model described above

    (3) Bussed up the signals, sent them over to the library block instantiation and connected it. In the process, I renamed the existing "ISC_2_HSTS" goto tag to "ISC_CTRL_2_HSTS" allowing for the new signal bus to be tagged as "ISC_QPD_2_HSTS."

The above top-level models as shown and at svn revs mentioned above have been test-compiled successfully on the build machine.

TITLE: 08/27 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 2mph Gusts, 0mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.24 μm/s 
QUICK SUMMARY:

The temperature excursion that EX VEA was having yesterday due to the clean room being turned on, has calmed down a bit.

Diag Main has a new message that I don't recall seeing before: "SEI_CONF might be stuck."  I recall that Jim wanted to do some HEPI coupling test on the BSC2 last night (tagging SEI). 

Currently both the JAC and the IMC are locked. ALS Y arm is unlocked and ISC_DRMI is down.
 

TITLE: 08/26 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:

Commissioners continued locking work and once they were done, Jim took over with SEI measurements overnight.
LOG:

• 2318-2324 Cleaning Room visit (betsy)
• Well pump is on until about 245utc/745pmPDT (tyler)
• 2345-0040 rfpd inventory checks at Staging (corey)
• 0107 Phoned Jim to let him know Commissioning work is done for the night.  He will begin his long SEI: measurements for the night (no one in the Control Room needed for his work).
  • 0115 Seismic to MAINTENANCE (Jim?)
  • 0118, 0119 BS St2 trips

TITLE: 08/26 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: Corey
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 19mph Gusts, 8mph 3min avg
    Primary useism: 0.03 μm/s
    Secondary useism: 0.10 μm/s 
QUICK SUMMARY:
JAC unlocked it's self as soon as I took over from TJ this mornin. 
Comissioners & crew were able to get H1 through a manual initial alignment.  They also took the ISC_DRMI guardian all the way up to PREP_PRMI_ASC[37].
We have largely not touched X-arm today due to the potential ETMX Rubbin Issue found here : alog # 91684 . 

The Temp inside EndX is elevated by a degree and a half due to the clean room being turned on and heating the VEA up.

Comissioners are still working on alignment.

Dust in the PSL room seems to be elevated due to the wind.

LOG:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         

Robert, Miranda

Last week, we noticed that the spectra for the two accelerometers, H1:PEM-CS_ACC_HAM3_PR2_Y and H1:PEM-CS_ACC_BSC1_ITMY_X, looked bad (as in, they looked to only be ADC noise). We went into the LVEA today and found that these two accelerometers were disconnected, likely due to the doors being removed earlier. We reconnected the former at 11:20 AM PDT and the latter at 11:24 AM PDT, 8/26/26. 

Comparing the buildup of H1:LSC-POPAIR_B_RF18_I_ERR_DQ between Nov 2025, at GPS time 1447346785, POPAIR RF18 I has a maximum of 168 counts. Today, while locked at PRMI with the buildups maximized, the same channel has a maximum of 62. This means that we are missing more than 70% of the power along this path.

We have previous trends from Ryan S and Ryan C, but they might have trended a normalized channel, which is confusing because the input power and the way we power normalize these channels has changed. Comparing the ERR channels is more straightforward.

POP A LF maximum was about 88 and now it is about 32.

Referencing these alogs: 91622, 91528

Keita has also confirmed that the whitening gains and digital gains of POPAIR RF18 and the modulation depth settings are all as they should be between these two times.

ndscope is updated to 0.22.0 on all the workstations.  Highlights include:

* Fixed bug that prevented showing some fast channels at full resolution

* Use shift-drag to constrain move/zoom to the time axis and use ctrl-drag to constrain move/zoom to the Y axis

* Allow full precision when entering scale & offset for a channel

* New plots now get custom trace width when set

* Use '--replay-id ' to access Arrakis replays

* Button to add Y cursors to all plots

Full change log here: https://git.ligo.org/cds/software/ndscope/-/blob/master/CHANGELOG.md#0220---2026-08-24

Jennie W, Elenna C, Keita K, Ryan S, Daniel S,

This morning JAC lost lock and couldn't re-lock. We solved this by clearing history in the JAC ASC and using the sliders to bring back JM1 osem values to those they had before the lock loss. NB: The process should be to clear history in the four ASC filter banks and in the JM1 suspension LOCK filter banks.

Zooming in on the time when we lost lock it looks like it was mainly DOF1 Y (yaw of PSL PZT) that got pulled away by the ASC as the JAC transmitted power dropped because the PZT ran out of range at the lower end. See zoomed in image here.

Because DOF1 now had a large output signal this then meant that the wavefront sensors were not centred in yaw and so prevented us re-locking as the alignment was so bad.

Here is the long term trends showing when we lost lock, when we cleared history, and when we re-locked.

A better temperature servo should help this.

In prep for a very potential (and hopefully quick) vent tentatively scheduled for ~Sept 8th, Randy is prepping the cleanroom spaces.  He will also turn on the big chamber 16" square cleanoom.  This will raise the temp in the End-X VEA and may effect the ETMx pointing, but that is all fine with ops/commiss.

The annulus ion pump for BSC9 just railed, about 15 minutes ago.
Nothing to do for now, but we will asses ASAP to see what is wrong with it.

TITLE: 08/26 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
CURRENT ENVIRONMENT:
    SEI_ENV state: MAINTENANCE
    Wind: 6mph Gusts, 3mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.06 μm/s 
QUICK SUMMARY: At 0412UTC the SEI_ENV state was transitioned to Maintenance, but I see no alog mentioning this. Dust at EX gone up near 1000 a few times overnight, we will need to check on that. 

No other alarms, we will continue locking commissioning today.

[Keita, Louis, Elenna, with input from others]

We locked PRMI again with the stronger BS top mass damping and no oplev damping. I also raised the damping gains of PRM, PR2, SR2 to -1. They have been set to -0.5 for a while now. I have SDFed these gains to -1 to help with locking.

> Since the PRMI buildups are so ratty, I am concerned about what is moving too much. Clearly the BS is the main culprit, but given the issues with PR2 where the damping was essentially doing nothing at low gain, I think we should raise the damping gain on all HSTSs to the original setting of -1. We can evaluate the noise effects in full lock, and perhaps have a gain setting for lock acquisition versus NLN.

I had some initial trouble locking MICH, and realized that the M3 drivealign gain was incorrectly set. Once I fixed that, it was much better. We need to check the guardian to make sure this gets set correctly.

> Haven't looked into this yet, will do so today.

Using a beamsplitter damping gain of -3 for most DOFs works well. We had some excess 1 Hz motion which I tracked down to having too high gain on BS T, so I've left that dof at -1 gain. SDF 1 2

PRMI locks quickly, and it appears by camera that the BS moves a lot less in this state during locking. However, the buildups were very shaky as we sat in PRMI locked for more than 30 minutes. I looked at the signals and it appears that the largest motion in POPAIR RF18 was around 0.2 and 0.3 Hz. Jim put the beamsplitter ISI in the fully isolated state, and this help reduce the motion.

> There is still excess motion in the corner at 0.1-0.3 Hz, mainly on the BS ISI. Jim is looking into this issue. This shows up strongly in the BS oplevs, but you can also see some of it in the PR3 oplev. This explains some of the wiggly-ness in the PRMI buildup.

The rest of the movement occurring while we sit in PRMI seems to be that the BS moves a lot at 0.45 Hz. However this signal is not visible in the top mass osems, so it would probably be better if we could engage MICH ASC.

> Sheila has pointed out that we should look into length-to-angle decoupling, going to work on this today.

I had some trouble engaging the BS ASC, which should drive to M2 and M1. I checked the error signals (AS RF45 B Q), and realized it didn't make sense (> as in the signals did not cross zero when buildups maximized, etc). So I then checked the phasing by driving a MICH length line at 88 Hz. The phasing was very bad, mostly in I not Q, and I fixed it by adjusting the phase by 70 degrees for all four segments. One segment moved the opposite direction of the other three segments (as in three segments reduced phase by 70 deg, one increased phase by 70 deg), which Keita found was because the relative phase of Q3 compared to Q1, 2, and 4 was off by 180. By flipping the demod phase on Q3, all of the relative phases between the segments was zero. I SDFed these phases. (screenshots attached of measurements and SDFs).

For good measure I rephased AS A RF45, although I would want to recheck the AS RF45 phasing when we have a DARM signal. (screenshots attached of measurements and SDFs).

> We need to rephase all ASC diodes I suspect.

With the rephasing, the MICH ASC error signals looked much more reasonable. I can engage the loops, but the pitch loop runs off after a minute or two, so I might have the gain sign wrong. The guardian is still set to engage MICH ASC FALSE, so it has to be done by hand.

Conclusions from today:

- we can keep locking PRMI/DRMI with no oplev damping

- we can keep locking with high BS top mass damping

- we can have the BS ISI ST2 boost ON when locking PRMI/DRMI

> before I get too confident, let's monitor over the next few weeks as Jeff suggests in his comment. However, we relocked multiple times to PRMI yesterday without any big kicks, all locklosses were due to me messing around with the alignment, or the JAC losing lock.\

> as a final note, the oplev damping still works, so if something happens that kicks the BS too much, ramping on the oplev gain for a few seconds can quickly damp the motion down (I suspect it's very overdamped)

***

Right after posting this alog I tried again with MICH ASC.

I feel confident that MICH yaw works with a gain of 0.5. This is flipped sign and slightly larger than the gain setting in the guardian for this state.

I think MICH P works ok with -0.5 gain. I was testing it and all was well until the JAC unlocked itself for a separate reason. It can take MICH P a few minutes to fall over though, so I won't change the guardian setting yet.
However, if you run the MICH ASC, the buildups are much quieter in PRMI.

***

> Logging in this morning to add some clarifying statements to the above, since I wrote this a bit hastily last night.

Besty, Oli, Ibrahim, Camilla. Follow on from 91650.

Betsy said that the OSEMINF INMON channels should not change much (over last two years has been < 300 counts) but twice in the last 2 months H1:SUS-ETMX_L1_OSEMINF_UL_INMON  has jumped ~2000 counts, both at the time of large earthquakes and when the EX ISI tripped:

• 24th June 2026 15:15 UTC- plot
• 17th July 2026 14:58 UTC - plot

Strangely this is not the same quadrant that has been the non responding (91650).

Miranda, Dave:

Over the past week we have documented the LHO PEM accelerometers and produced an as-built  wiring drawing

This was in response to a possible misreading of accelerometer(s) with the wrong channel names.

We found three accelerometers with incorrect names, which date back to pre-O4, so I'm tagging DETCHAR.

We fixed this at 16:00 Thursday 13th August 2026 PDT by remapping the BNC connections on the front panel of APC1. The cable going to port12 was moved to port13, that going to port13 was moved to port14 and that going to port14 was moved to port12.

We tap-tested the EBAY_FLOOR accelerometer at 16:10 and this showed up on H1:PEM-CS_ACC_EBAY_FLOOR_Z_DQ

Mayank, Sheila

We now have a number of power measurements at the HAM3 viewport, with corresponding estimates of the beam spot position on PR2 (from  July 2024 78878, yesterday's measurement of 8mW at PR3 yaw -74 urad 82722)

We used Elenna's new calibration of PRC power 8724 to estimate that we have 2.53kW of power in the PRC beam.