aLIGO LHO Logbook

H1 SEI - Comment to CRS Chamber Side Testing Continues

michael.ross@ligo.org — Tue, 23 Jun 2026 18:34:41 -0700

Author: michael.ross@ligo.org

Report ID: 90727

We took a quick spectrum to check the HoQI performance. The CRS is very rung up so this noise floor is not indicative of the final performance. Yet the noise floor already looks good.

Images attached to this report

H1 SEI - CRS Chamber Side Testing Continues

shoshana.apple@ligo.org — Tue, 23 Jun 2026 18:25:50 -0700

Author: shoshana.apple@ligo.org

Report ID: 90715

[Arnaud, Michael, Jim, Fil, Shoshana]

As mentioned in 90702, one of the readouts for the CRS HoQI amplifier wasn't working, after investigating we figured out that it was an issue with a broken op-amp in a transimpedance amplifier (HoQI B, channel E/COS). Fil switched out the op-amp so we now have a working chassis. Our best guess is that the op-amp failed after plugging it into the rack.

The HoQI on the left side of the CRS (SN01-005, currently HoQI2) had much lower fringe visibility than the other one (SN02-007) since yesterday. We figured out that the laser collimator was positioned in a way where the beam wasn't hitting the center of the photodiodes. The laser collimator was re-aligned and we were able to greatly increase the fringe visibility so the HoQIs now match.

HoQI 1 (SN02-007), SIN: 86.7%, COS: 79.4%, MCOS: 84.9%

HoQI 2 (SN01-005), SIN: 81.4%, COS: 82.7%, MCOS: 80.1%

CRS was balanced, currently has a estimated resonance frequency of 15.7mHz, but we will re-check it in the morning. We are leaving the laser on over night hoping to get some noise measurements, both due to the air currents in the clean room, and the fact that we didn't ground the damping capacitors, it looks unlikely that it will damp down overnight.

Arnaud got the ellipse fitting working, the python script is in /opt/rtcds/userapps/trunk/isi/h1/scripts/write_ellipse_values3.py

We added a gain 0.0847 um/cnt (1064 nm/4pi) to the HoQI Dist filter banks to calibrate the HoQIs into distance. We also changed the CRSRY_PHI_SUM matrix elements to 2.75 to put the RY channels into urad.

An unrelated mystery: HoQI1 and HoQI2 are switched, we aren't sure where in the chain they get flipped, but right now we are guessing it's at one of the cables to the chassis

SEI

H1 SUS - BS Sign Convention fixed throughout signal path

oli.patane@ligo.org — Tue, 23 Jun 2026 18:12:25 -0700

Author: oli.patane@ligo.org

Report ID: 90725

Previously (90441), Tom, Ibrahim, and I had found out that the QOSEM coil drivers were wired opposite as compared to other OSEMs. To compensate for this at the time (since we were attempting to use damping), we had swapped the signs of the damping gains. But we had only swapped those gains, meaning that other actuation coming through the TEST or OPTICALIGN filter banks was still pushing the coil drivers the opposite way from expected. Today we finally decided to fix it to reduce confusion wrt the direction the BS was moving when offsets were put in (offsets were moving the BS in the opposite direction than expected).

To do this all I did was put the M1 DAMP filter gains back (before, after) to being negative and then swapped the signs of the gains in M1 COILOUTF (before, after). To put the beamsplitter back with the OPTICALIGN offsets that it had before, I then swapped the sign of each offset.

I will update the SUS Sign Conventions document to mention that the QOSEMs require the opposite COILOUTF signs from nominal.

So now EVERY BBSS OPTICALIGN slider offset from before 2026/06/24 00:50 UTC requires the opposite sign to be recreated.

Images attached to this report

H1 AOS - Comment to BS Alignment with SQZ Beam, got MICH fringes with SQZ and IFO beam

keita.kawabe@ligo.org — Tue, 23 Jun 2026 17:57:05 -0700

Author: keita.kawabe@ligo.org

Report ID: 90724

Since IMTX was moved today, I had to move PR3 to compensate in order to regain IMC flashes in the AS camera as well as ISCT1 camera.

H1:SUS-PR3_M1_OPTICALIGN_P_OFFSET is now -247.0 (used to be -140).

H1:SUS-PR3_M1_OPTICALIGN_Y_OFFSET is now -245.0 (used to be -583).

H1 SUS - Comment to BS Pitch Pointing Offloaded

ryan.short@ligo.org — Tue, 23 Jun 2026 17:46:48 -0700

Author: ryan.short@ligo.org

Report ID: 90723

Keita's note: After Jason recentered BS oplev, we changed the BS sliders to see the sign of the sliders (we knew that they were flipped) and how bad the pit to yaw coupling was.

Sign of the H1:SUS-BS_M1_OPTICALIGN_P_OFFSET and H1:SUS-BS_M1_OPTICALIGN_P_OFFSET are systematically wrong.

Positive PIT (right column top) in the slider consistently makes negative PIT on oplev, M2 OSEM and M1 OSEM, i.e. positive PIT tilts the BS up when positive offset is added to the pit slider.

Same story for YAW, negative PIT (left column top) in the slider consistently makes positive YAW for all sensors available, i.e. positive YAW rotates the BS clockwise when viewed from the top.

Arnaud and the gang will fix the sign issue.

PIT to YAW coupling is about 2 YAW per 1 PIT (i.e. PIT actuation make BS move more in YAW). YAW to PIT is not bad.

Positive PIT of 50 counts (uncalibrated) made negative 10urad in PIT and negative 20urad in YAW according to oplev. This agrees with our experience of observing how the beam spot moved in chamber as well as on the AS and ICST1 cameras when trying to move BS in PIT using the slider.

Interestingly, P2Y coupling seems to be OK for M1 (1:0.17 if we trust the QOSEMs), bad (about 1:0.7) for M2 and absolutely terrible (1:2) for M3 oplev.

Negative YAW of 20 counts made positive YAW of about 30urad and almost unmeasurable amount of PIT according to oplev.

Images attached to this report

H1 CDS - new trace color system for ndscope

erik.vonreis@ligo.org — Tue, 23 Jun 2026 17:27:38 -0700

Author: erik.vonreis@ligo.org

Report ID: 90722

Ndscope has a new system for picking trace colors that tries to maintain a high contrast between the trace and the background.

You can test the new system by running "ndscope-test" instead of ndscope on any workstation, laptop, or login portal. Give it a try and let me know what you think.

H1 SUS - BBSS Model M1 to M3 TFs and DC values

oli.patane@ligo.org — Tue, 23 Jun 2026 17:24:01 -0700

Author: oli.patane@ligo.org

Report ID: 90720

Arnaud, Oli

As part of our BBSS alignment and investigation, I used /ligo/svncommon/SusSVN/sus/trunk/BBSScomparetripleparams.m to look at the DC values of our current model when actuating at M1 and reading out at M3.

I made a few edits to comparetripleparams.m in order to allow me to do this easily, and I've committed those changes as r13039.

The plots (P, Y) show that the DC value for M1 P to M3 P is 0.029 rad/Nm and M1 Y to M3 Y is 0.129 rad/Nm. These plots can be found in /ligo/svncommon/SusSVN/sus/trunk/BBSS/Common/Results/comparetripleparams/comparetripleparams/2026-06-23_M1toM3Model/triplemodelcomp_2026-06-23_M1toM3Model_M1toM3.pdf r13040.

We then converted into cts/N using (1e-6)*(1/DACdrive)*(1/coilDriver)*(1/forceCoeff).

For this we used DACDrive = 20/2^16 cts/V, forceCoefficient = 1.694 N/A, and coilDriverTransconductance = 0.011919 A/V. The reason why DACDrive = 20/2^16 cts/V and not 20/2^28 is because we already compensate for the difference between a 16-bit DAC and a 28-bit DAC in the COILOUTF filter bank so we don't need to put that into our calibration.

This gives us:

Calibration factor [cts/N] = (1e-6)*(1/(20/2^16[cts/V]))*(1/0.011919 [A/V])*(1/1.694 [N/A])

= 1.623e5 [cts/N]

Then multiplying this calibration factor by our earlier fractional values for P and Y gives us:

Pitch slider calibration : 4.7e-3 cts[M1]/urad[M3]

Yaw slider calibration: 20.9e-3 cts [M1]/urad[M3]

Images attached to this report

H1 SUS - Comment to BS Pitch Pointing Offloaded

jason.oberling@ligo.org — Tue, 23 Jun 2026 17:21:02 -0700

Author: jason.oberling@ligo.org

Report ID: 90721

The BBS OpLev has been recentered. I had to yaw the beam onto the QPD, as it was not on it. Once recentered, the SUM counts were around 2400, which is much lower than for the old BS, which was up around 20k. I checked the Output Configuration Switch on the BBS OpLev chassis in the biergarten and it has not changed, the amount of gain is still 0 dB. The other explanations are the coating on the BBS (OpLev beam is at 635 nm, which is not a design wavelength for the coating, so the %R at 635 nm for the BBS could be very different than the old BS) and a failing OpLev laser. I'll check the power output from the laser to see how it's doing (likely tomorrow).

H1 SUS - BS Pitch Pointing Offloaded

ryan.short@ligo.org — Tue, 23 Jun 2026 17:14:47 -0700

Author: ryan.short@ligo.org

Report ID: 90719

B. Weaver, C. Compton, R. Short

Carrying on from alog90708 posted at lunch, Betsy, Camilla, and I offloaded the BS pitch sliders mechanically at the suspension. This was a tad tricky since we were looking at the beam(s) at HAM3 in front of PR2, so we had to work out blocking 1 ITM beam in order to not be confused by both beams crossing each other after the long PR chain of optics. In the end, we worked out the process to bring the BS PIT slider from +1000 to 0 which meant pitching the BS optic HR "up" (PUM roll bar "in"). Unblocking the other ITM, we got both beams overlapping onto each other with a little more slider to see how much better we could get them and see flashes in the AS_AIR camera (PIT = -300, YAW +1560).

Once back in the control room, Keita scanned BS alignment to find the SQZ beam reflected by ITMX as well as ITMY in AS camera as well as ISCT1 camera, ending with BS PIT = -520, YAW = 1677. With this alignment, IMC flashes reflected by ITMX as well as ITMY were visible in both of the cameras. Though SQZ beam and IMC flashes are not coaligned, the corner alignment is already pretty good as of now.

At this point we want to:

1) Recenter the OPLEV

2) Go in and physically calibrate which way the sliders go as seen on the oplev and at the HAM3 PR Beams since there is confusion around the sliders (direction, calibration, cross coupling)

3) Based on 2) Potentially make a request for HEPI YAW correction tomorrow when they resume HEPI "fine" alignment and actuator reattachment (TBD convo with SEI/IAS)

4) Get on with landing HEPI/actuator attachment, etc.

5) Final round of BS PIT SUS mechanical Offloading

ISC

H1 General - OPS Tuesday Day shift summary

ryan.crouch@ligo.org — Tue, 23 Jun 2026 16:33:02 -0700

Author: ryan.crouch@ligo.org

Report ID: 90710

TITLE: 06/23 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY: SPI in-chamber installation was finished yesterday, CRS work, and alignment work continued ending with Jason recentering the BBS OPLEV as of 23:30 UTC.
LOG:

Start Time	System	Name	Location	Lazer_Haz	Task	Time End
20:18	SAF	LVEA IS LASER HAZARD	LVEA	YES	LVEA IS LASER HAZARD	12:18
14:30	FAC	Kim	LVEA	Y	Tech clean	15:16
15:44	FAC	Kim	LVEA	Y	Tech clean	17:03
16:20	FAC	Randy	LVEA	Y	Moving scissor lift out of E bay	16:33
16:22	SAF	Betsy	LVEA	Y	Opening light pipe	16:24
16:44	FAC	Chris	Ends	N	End Station FAMIS checks	18:39
16:44	PEM	Robert	EndY	N	Grounding study	17:43
17:01	SEI	Jim	LVEA	Y	HAM3 CPS work	19:31
17:13	ISC	Betsy	LVEA	Y	HAM3 pictures	17:30
17:15	CDS	Dave	REMOTE	N	DAQ restart	17:30
17:47	SEI	Mitch	LVEA	Y	Join Jim	19:20
18:14	FAC	Tyler+1	LVEA	Y	Walkthrough with vendor	18:31
18:15	ISC	Camilla, Betsy	LVEA	Y	Alignment checks	18:48
18:22	PEM	Carlos, Shrey, Matilda	Site, Xarm	N	Installing seismometers, overpass	23:03
18:57	CRS	Michael, Shoshana, Corey	LVEA	Y	CRS work by HAM3	20:05
19:22	ISC	Betsy	LVEA	Y	HAM3 checks	19:25
19:37	VAC	Gerardo	LVEA	Y	Viewport (1) removal by HAM5	23:05
19:40	PEM	Robert+3	EndX	N	PEM checks, grounding study	21:40
20:06	VAC	Jordan	LVEA	Y	Join Gerardo @ HAM5	20:30
20:11	CDS	Dave	Roof	N	Looking at fire	20:21
20:12	ISC	Betsy, RyanS	LVEA	Y	HAM3 work, alignment, Betsy out 22:15	22:47
20:38	SEI	Jim	LVEA	Y	CPS work, SEI cabling around HAM3	00:11
20:59	ISC	Camilla	HAM3	Y	Join team alignment	22:43
21:01	SEI	Mitch	LVEA	Y	CRS work, HAM3	21:17
21:04	VAC	Jordan, Jake, Owen	LVEA	Y	Remove RGA from CP1	23:15
21:35	CRS	Michael, Shoshana	LVEA	Y	CRS work	Ongoing
22:44	SUS/IAS	Jason	LVEA	Y	Recenter BBS OPLEV and auto OFF/ON the FARO	Ongoing
22:55	SPI	SPI LASER IS ON	LVEA	Y	SPI LASER is ON	Ongoing
22:45	SPI	Jeff	LVEA	Y	Turn on SPI laser in @ 22:45	22:56
22:59	SEI	Mitch	LVEA	Y	Talk to Jim	23:08

A wildfire sparked up to our southwest by Benton City around 19:00 UTC, the smoke could easily be seen to the left of Rattlesnake. Multiple helicopters, and a plane were out fighting it. As of the end of shift it looks like they've mostly put it out based on the smoke or the lack of.

H1 SPI - SPI Pathfinder Analog LO Phase Rotators Set to 0.0 [deg] and 0.0 [deg]

jeffrey.kissel@ligo.org — Tue, 23 Jun 2026 16:11:30 -0700

Author: jeffrey.kissel@ligo.org

Report ID: 90718

J. Kissel, for J. Freed At the last minute on 2026-06-18, Josh figured out that we had errantly been sending the SPI's double mixer two copies of a COS wave of 4096 Hz rather than a SIN and COS (LHO:90680). This was because someone had errantly put a 90 [deg] rotation in the SIN analog output path. He fixed it before he left, but didn't save it in the SDF system and it got lost during Monday's bootfest of h1seih23 (LHO:90689). I'm not sure if Josh (or anyone) tuned it to any specific value, but I've changed the SIN analog rotation phase to 0.0 and accepted it in SDF so we don't lose it. Josh may add some more details in the comments below, in the comments to his LHO:90680.

H1 SPI - SPI Pathfinder Laser ON

jeffrey.kissel@ligo.org — Tue, 23 Jun 2026 16:07:33 -0700

Author: jeffrey.kissel@ligo.org

Report ID: 90717

J. Kissel I'm looking to get some overnight data of the SPI pathfinder so start looking at science signals and debugging. Jennie has been turning OFF the laser via the external-to-PSL Uniblitz shutter controller (see LHO:90491) over this past long weekend, and each night this week because she was worried about the stray beam from the FBR_PWRIN PD, but again -- this is 0.2 [mW] and not an issue for humans or equipment as long as the LVEA is laser hazard. She didn't know the power was so low, and followed her good instincts. But yeah, I want to get some over night data, so I've turned ON (unshuttered) the SPI laser input via the Uniblitz shutter controller box by the PSL. I'd like to leave it ON as long as the LVEA is laser hazard. If we need to go back to laser safe and I'm not around, one can easily shutter the laser by turning OFF the controller box: power it off with the rocker switch on the back, or unplugging the box from the wall, or both. With no power, the shutter defaults to CLOSED, which blocks the SPI pick-off path (only) from inside the PSL, thus making the entire SPI laser system laser safe anywhere outside the PSL.OpsInfo, SPI

H1 SUS - BBSS Makeshift Test Stand Optical Lever Gross Pointing and Range Check

ibrahim.abouelfettouh@ligo.org — Tue, 23 Jun 2026 15:08:36 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 90709

Ibrahim, Oli, Thomas, Betsy

Before we flew the BBS in, we did a sanity-check experiment to compare slider values with a laser-pointer optical lever. This experiment follows Jeff's G1200698 math for an optical lever (picture also attached).

Setup:

A laser pointer was pointed at the BBS HR side such that the HR and AR reflections could be seen on a paper near the laser pointer. The initial position was recorded on a paper, and then slider values were driven to their maximum range in P and Y. The distance between the laser source and the HR surface was recorded. The experiment was done with BOSEMs and then with QOSEMs.

Method:

When the laser pointer is incident on the BBS, there are two reflected beams (AR and HR). The average distance of these was taken along with the average distance from the BBS. This was done by calculating the distance to the BBS and adding the half-thickness of 30mm. This gives us "one beam" and "one distance' to go off for P and Y. See the attachment below for an image of the paper used during the experiment. This was done once for BOSEMs and then again with QOSEMs.

A few notes:

The setup was replicated and the distance was remeasured on a different day and this is why the distances are different.
The QOSEM as-it-is is inversed in its actuator sign convention and you can see this in the attached diagram. One of our action items is to rectify this. So right now, +P = Pitching up instead of down with respect to the HR. In general, we will abide by T1200015, the SUS/Actuator Sign Convention.

Results and Analysis

Pitch is in purple and Yaw is in Orange. The equation used was obtained from "G1200698, the Oplev Infamous Factor of Two", which is essentially the same outline as our experiment, a diagram of this is attached.

This equation is: DØ= DS/2L Where,

Ø is the angle in radians (adjusted to urad below), S is the displacement in the beam spot, L is the distance from the laser source to the optic.

For these data, the total range of the Opticalign sliders was considered (from lowest negative to highest positive). Thus, a half the range would apply if the sliders were zeroed.

	BOSEM	QOSEM
Distance from HR surface (in)	130	118
Distance from HR surface (mm)	3302	2997.2
Average distance from optic	3332	3027.2
Pitch Displacement Total - +-1500 cts	5.5	5.75
Yaw Displacement Total +-4000 cts	46.75	40.75
Pitch Angle Swept (urad)	825.33	949.72
Yaw Angle Swept (urad)	7015.31	6730.64
Total Pitch Count Sweep (+-1500)	3000	3000
Total Yaw Count Sweep (+-4000)	8000	8000
Pitch urad/Ct	0.28	0.32
Yaw urad/Ct	0.88	0.84
Pitch Ct/urad	3.63	3.16
Yaw Ct/urad	1.14	1.19

Conclusion:

For a QOSEM Drive:
- Pitch at M3 read +-475urad (1/2 the total sweep of 949.72 shown above), which is equivalent to 3.16 Opticalign Cts per urad.
- Yaw at M3 read +-3365urad (1/2 the total sweep of 6730.64 shown above), which is equivalent to 1.19 Opticalign Cts per urad.
BOSEM and QOSEM ranges are comprable
No cross coupling was observed. Remember that this was done on the test stand a few weeks ago, before we found P:Y and Y:P coupling in chamber.

Next Steps:

Next, we're going to compare these results with the M3 AOSEM readouts once these are reliable. We will also compare these results with the model (which is used to corroborate slider calibration). Ultimately, this will help with the calibration of our slider values (both within the actuator slider actuation vs. sensing and from counts to real units).

Once we get a working OpLev (it's not on the BBS right now), we'll be able to get a more fine measurement of this kind.

Again, this is just a gross alignment check for information about our pointing and the capacity of our actuation.

SUS

Images attached to this report

Non-image files attached to this report

OpticalLever_FactorOfTwo_G1200698-v1.pdf

H1 SPI - 2026-06-22 SPI Pathfinder -- Installation Complete!

jeffrey.kissel@ligo.org — Tue, 23 Jun 2026 14:21:49 -0700

Author: jeffrey.kissel@ligo.org

Report ID: 90716

J. Kissel, J. Wright, T. Shaffer, J. Warner, J. Freed (belated aLOG covering 2026-06-22 activity) After enjoying a lovely long, Juneteeth Holiday weekend, TJ and I wrapped up the few loose ends that were left after the 2026-06-18 super push to get everything installed (see last update; LHO:90676). - As a fall out of LHO:90667, Jim, Arnaud and I discussed the pros and cons of using the current, D1000907-v7, balance mass "Payload & Suspended Mass Assembly" arrangement in regards to the W9 corner. We concluded that leaving the D1000907-v4 configuration for this corner in place -- i.e. having 11.6 [kg] of mass in small, modular, optional components -- was better that having one "giant" 10 [kg] mass in "the same" location (on the table top, but in the same W9 corner). As such, we left the plates as re-installed on LHO:90713, with the acknowledgement that the final configuration to create a balanced ISI may be different even further than D1000907-v7. - Using a beam profiler, we measured the Beam Profile of the beam returning from M_C1 on the HAM23 ISIJ Reflector. This is to, at least roughly, confirm the radii of curvature of the M_C1 mirror. We expected a 2 [mm] diameter beam, and we got a 2 [mm] beam diameter. A more thorough aLOG to come. - We did NOT address the stray beam that Jennie mentions in her summary -- yet. I'll also write a separate aLOG on this, but in short -- it's a ~0.2 [mW] beam that's what ~18% reflection there is off of a silicon diode, and it hits the -X/-Z rim of the chamber of the +Y door, and the (splotchy) spot size is ~4-5 [mm] in diameter. The SPI team has been aware of this beam since testing in the optics lab (see mention of it, e.g. in LHO:90455), but hoped that it would land on some part of the SPI Shroud assembly, but it *just* misses it. With this last item, we consider the Installation and Integrated Test Plan COMPLETE (T2500024) ... to as good as possible with the HAM3 ISI still locked. And that ... qualifier is a "just in case" qualifier, as it's a "we'll see what happens" when the ISI gets unlocked, and we've got an excellent amount of remote adjustability to be able to recover the MEAS IFO's alignment if HAM3 moves a lot between - "locked," - "re-balanced and damped" and - "isolated with feedback and DC positioning engaged." Essentially, we've launched the SPI pathfinder into space, and now its up to out built-in remote controlled actuators and sensors to take us home to achieve our scientific goals (see T2600019). Super congrats to all, and similarly large thank you. We did a thing!SEI, SPI, SYS

Images attached to this report

H1 SEI - Comment to ISI HAM3 Wide Wall Balance Masses vs. SPI

jeffrey.kissel@ligo.org — Tue, 23 Jun 2026 13:48:31 -0700

Author: jeffrey.kissel@ligo.org

Report ID: 90714

Masses were re-installed as of 2026-06-18! See LHO:90713.SEI, SPI

H1 SPI - Comment to SPI install update - day 6

jeffrey.kissel@ligo.org — Tue, 23 Jun 2026 13:47:43 -0700

Author: jeffrey.kissel@ligo.org

Report ID: 90713

Note mentioned in the summary of activities in the main entry -- per LHO:90667, we re-installed all the ballast or balance mass discussed during this 2026-06-18 day's session. See attached "after" picture.

Images attached to this report

H1 CDS - Comment to DAQ restart for new PWRCS Beckhoff Chiller channels

david.barker@ligo.org — Tue, 23 Jun 2026 13:44:50 -0700

Author: david.barker@ligo.org

Report ID: 90712

Here is a random new channel which has non-zero data trended back one month to view its data back when it had its original name.

Images attached to this report

H1 CDS - DAQ restart for new PWRCS Beckhoff Chiller channels

david.barker@ligo.org — Tue, 23 Jun 2026 13:40:24 -0700

Author: david.barker@ligo.org

Report ID: 90711

WP13303 Reimage PWRCS Beckhoff, update Corner HEPI Pump controller INI

Patrick, Erik, Jonathan, Dave:

Patrick created a new H0EPICS_PWRCS INI file. All of the EPICS channel names have changed since the first version of this system, and 40 of the new channels have old-channel equivalents. To preserve recent minute trends, the data acquired so far were transferred to the new names as part of the upgrade.

The sequence followed was:

- Remove the old names from the edc_green_ioc IOC. 43 disconnects at this point (40 from H0EPICS_PWRCS and 3 from H1EPICS_HEPIPUMPL0)

- Create the copy scripts to be ran on TW0,TW1 to copy the old files to the new, so that the new channels will "continue from where we left off"

- Create the new H1EDC.ini and verify its changes.

- Stop daqd on TW0 and TW1

- Run the copy scripts on TW0 and TW1

- Restart the 0-leg, followed quickly by restart of the EDC.

- Wait till 0-leg was fully operational, including TW0

- Restart the 1-leg

All went well except for the usual GDS1 needed a second restart, FW1 restarted itself after 5 minutes.

H1 AOS - BS Alignment with SQZ Beam, got MICH fringes with SQZ and IFO beam

camilla.compton@ligo.org — Tue, 23 Jun 2026 12:50:39 -0700

Author: camilla.compton@ligo.org

Report ID: 90708

Continued from 90691. Betsy, Keita, Sheila, Oli, Eric, Camilla, Ryan S, Jenne

First thing, we went back to alignment we had ITMX SQZ the "flashes" and "fly-bys" yesterday, put the same size oscillation on the BS, but saw no flashes of fly bys. Betsy took a video of what the two SQZ beams looked like at PR2 at this alignment, they were crossing each other.

We then rethought the alignments from yesterday, we are leaving:

ITMX and ITMY at March DRMI top mass OSEM sensors
ZM4 and ZM5 to get SQZ beam on SQZT7 irises
ZM6 to O4 sliders.
SR3 at the Oplev/slider positions of March DRMI/O4 (all similar)
SR2 Yaw slider back to O4, Pitch to get SQZ ITMY beam on AS_AIR (+440urad PIT sliders different from O4).
SRM aligned to improve SRY fringes (+200urad PIT sliders, +400urad YAW sliders different from O4).

Once we did this, we had SRY fringes, Betsy and I then adjusted the BS to bring the beams back on top of each other at PR2. This was a change in the BS sliders from (P 1000, Y 1290) to (P 1350, Y 1180).

Keita then wobbled ITMX and found the SQZ beam off ITMX! Aligned ITMX to get MICH flashes at AS_AIR, AS_A/B and ISCT1 REFL. He had to move ITMX from (P -96, Y 104) to (P -280, Y 94).

He then got the PSL IX and IY reflection in the AS_AIR camera in this alignment. Sliders at this alignment attached.

However as we are not sure we trust the ITMY alignment form top mass osems (from 90551), we want this Pitch change to be in ITMY, so ITMX is at it's known DRMI pointing. We could try to walk these, maybe along with SRC which might reduce some of our Pitch differences in SR2 and SRM. This change is so small that we will go ahead with mechanically offloading BS Pitch. The BS YAW will not mechanically changed.

The OMs are also not currently in their O4 sliders/osems position, attached. We could verify the SQZ beam pointing by putting these back if we thought that was needed.

Images attached to this report

H1 CDS - Workstations updated

erik.vonreis@ligo.org — Tue, 23 Jun 2026 09:58:30 -0700

Author: erik.vonreis@ligo.org

Report ID: 90707

Workstations were updated and rebooted. This was an os packages update. Conda packages were not updated.

H1 SEI - Comment to ETMY BRS not damping down

shoshana.apple@ligo.org — Tue, 23 Jun 2026 09:55:27 -0700

Author: shoshana.apple@ligo.org

Report ID: 90706

Michael is in this week and fixed the EMTY BRS by raising the upper threshold (H1:ISI-GND_BRS_ETMY_HIGHTHRESHOLD) from 4000-->8000 for 20 minutes, see 90693

Current Thresholds:

H1:ISI-GND_BRS_ETMY_HIGHTHRESHOLD: 4000

H1:ISI-GND_BRS_ETMY_LOWTHRESHOLD: 2000

Looking through ndscope it the same changes were made to the ETMX BRS, raising the thresholds

H1 SEI - Comment to CRS Chamberside testing started

michael.ross@ligo.org — Tue, 23 Jun 2026 09:45:06 -0700

Author: michael.ross@ligo.org

Report ID: 90705

Adding numbers for the fringe contrasts for each PD:

HoQI 1 (right):

Sin: 85%

Cos: 80%

MCos: 84%

HoQI 2 (left):

Sin: 70%

Cos: 5% (electronics issue)

MCos: 71%

H1 General - OPS Tuesday Day shift start

ryan.crouch@ligo.org — Tue, 23 Jun 2026 07:31:10 -0700

Author: ryan.crouch@ligo.org

Report ID: 90704

TITLE: 06/23 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: MAINTENANCE
Wind: 3mph Gusts, 1mph 3min avg
Primary useism: 0.01 μm/s
Secondary useism: 0.08 μm/s
QUICK SUMMARY:

Continuation of CRS, and aligment today
DetChar FF in the MPR, try to use the kitchen door

H1 SEI - ITMs as-built balance mass pictures

arnaud.pele@ligo.org — Mon, 22 Jun 2026 19:35:24 -0700

Author: arnaud.pele@ligo.org

Report ID: 90703

Pictures of as-built balance mass of ITMs taken today to compare with drawings in anticipation of rebalancing both ITMs with the added baffle weight

ITMY:

table: pic1, pic2, pic3
corner 1 side wall: pic4
corner 2 side wall: pic5
corner 3 side wall: pic6 and pic7

ITMX:

table: pic8, pic9, pic10
corner 1 side wall: pic11
corner 2 side wall: pic12, pic13
corner 3 side wall: pic14, pic15

Images attached to this report

H1 SEI - CRS Chamberside testing started

arnaud.pele@ligo.org — Mon, 22 Jun 2026 19:05:04 -0700

Author: arnaud.pele@ligo.org

Report ID: 90702

Shohana, Michael, Fil, Jim, Arnaud

wp 13344

Following up from 90652. The CRS chamber side testing started:

The CRS electronics (HOQI amplfier, Laser Driver and TEC controller) and laser were installed in the TCS-R2 rack, where the permanent cables are installed (see pic1)
The E-stop was mounted on the TCS-R2 rack with label 'CRS local E STOP' (see pic1)
The db25 in the CER was plugged to the HAM AA chassis going to ADC
db25 and fiber patch cables were ran on the floor from the rack to the 'CRS' cleanroom (see pic2)
The laser was turned on to verify HOQI signals and HOQI alignment. The 2nd channel on HOQI B from the TIA is saturating (it was working last week) so we pulled the board out and will inspect in the EE shop tomorrow. In terms of algnment we are getting >70% fringe visibility and will continue to tune it tomorrow.

Images attached to this report

H1 SUS - BBSS M2 BOSEMs Centered, M3 AOSEMs cabled and centered

ibrahim.abouelfettouh@ligo.org — Mon, 22 Jun 2026 19:02:17 -0700

Author: ibrahim.abouelfettouh@ligo.org

Report ID: 90701

Ibrahim, Oli

Today, Oli and I installed and centered the M2 BOSEMs and centered and attached the cables for the M3 AOSEMs. AOSEM and BOSEM cams were also inspected and centered.

A few notes:

One of the M3 lower cables was not taut enough (LL) so after centering it was removed and stowed securely. We'll think more on how to fix this to the structure safely from the optic. LLO attached theirs around the LS figure 8 so we will likely do the same. See a picture.
M3 OSEM values haven't been normalized via the OLG adjustment so they "look" uncentered but they are centered. This will be applied tomorrow so they should look even on the spedometers.
As a side-quest, we were also checking for rubbing (for the 3rd time) to see if there's a reason behind P:Y (and Y:P) coupling in OSEM slider readouts - alog 90697. We found no evidence of rubbing or touching, which is frustrating. We will return to it tomorrow.

Next:

We are now able to take BRD measurements in-chamber so we'll do that tomorrow. Hopefully, the P:Y coupling issue is resolved. We'll see.
Re-attach lower M3 cable (LL) and fix them to their final resting place.
Take TFs.

SUS

Images attached to this report

H1 SUS - BBSS Pitch Yaw Coupling Investigation - Coil Driver Chain

thomas.roocke@ligo.org — Mon, 22 Jun 2026 18:19:28 -0700

Author: thomas.roocke@ligo.org

Report ID: 90697

[Tom, Ibrahim, Oli]

Summary: The yaw / pitch coupling seen on the BBSS is not due to the the coil driver chain.

As noted in LHO alog 90665, we are seeing strong pitch yaw coupling on the BBS, when actuating via the top stage QOSEM coils. When we try and adjust the optic yaw we see a 1:5 response in pitch and vice versa. This is seen in both the QOSEM readouts, and visually using an IR beamcard on the PSL beam bouncing off the optic.

To investigate whether the cause was electronic in nature, we went into chamber to ensure that only the F2 and F3 QOSEM coils are being driven when requesting yaw drive. We used a multimeter to measure the voltage drop across the coils, to determine whether theyre being driven or not. As we expected, only the F2 and F3 coils are being driven, with equal and opposite magnitude, when trying to drive yaw. This suggests that this coupling is not coming from the coil electronics chain, or an issue in CDS.

H1 IOO - Aligned JAC wavefront sensors

jennifer.wright@ligo.org — Mon, 22 Jun 2026 17:54:33 -0700

Author: jennifer.wright@ligo.org

Report ID: 90700

I took an opportunity while the BSC team was in the control room and opened the light pipe and aligned the WFS on IOT1 while JAC was unlocked.

This was done at 200mW.

I used the manual adjustment knobs on the picomotor mounts as the IOT1 table is not hooked up to its pciomotor controller currently.

Got both WFS A and B as close as I could using this method. NB: pitch and yaw on QPD A are swapped as the manual pitch adjuster changes the yaw degree of freedom. I need to check this in the physical wiring for the QPDs.

Images attached to this report

H1 SPI - Comment to SPI install update - day 6

jennifer.wright@ligo.org — Mon, 22 Jun 2026 17:46:56 -0700

Author: jennifer.wright@ligo.org

Report ID: 90699

Just did an 8 hour trend of the fiber power monitor channels for REF and MEAS channels (left two plots) and the optical lever QPDs (right two plots) to check whether we expect variations on the order of ~2V on the QPDslike we saw on Thursday before and after baffle installation.

From this trend the power appears to drift more than this for two hours after unshuttering the laser (around 15:56 UTC), but once it reaches a steady state both QPDs were only drifting by 1V and the fiber power input monitor PDs by 1V or less.

Conclusion: I think we would have seen a dramatic power drop on Thursday when we installed the shroud, that I would expeact to have been much larger than the trends I saw today.

Images attached to this report

H1 SQZ - SQZT7 Beam profiles/alignment, no progress made.

camilla.compton@ligo.org — Mon, 22 Jun 2026 17:02:59 -0700

Author: camilla.compton@ligo.org

Report ID: 90698

Eric, Ryan S, Camilla

Went onto SQZT7 and checked on the M^2 profiler. It needed their alignment procedure ran but as we're aren't at a set alignment we did not do this yet.

In the control room we used the ASC set up in 88777 and had to adjust the H1:SQZ-ASC_TRIGGER_THRESH_ON/OFF, it worked well when we changed PSAMS but we then realized we needed a ZM4/5 ASC rather than a ZM5/6 ASC for SQZT7 profiles. Tried just changing the output matrix, did not work.

Strangely, when I used the SQZ IFO ASC screen's "!graceful clear history", we now have outputs in the LOCK OUTPUTs but the beam looks a lot clearer on AS_AIR camera. We are now in a different alignment than we have been, but it's better on AS_AIR so we'll reassess tomorrow...

H1 General - OPS Monday Day shift summary

ryan.crouch@ligo.org — Mon, 22 Jun 2026 16:32:37 -0700

Author: ryan.crouch@ligo.org

Report ID: 90695

TITLE: 06/22 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY: CRS, SPI at HAM3, BS / input alignment work, and a little bit of beam profiling at HAM7 continued today.
LOG:

Start Time	System	Name	Location	Lazer_Haz	Task	Time End
20:18	SAF	LVEA IS LASER HAZARD	LVEA	YES	LVEA IS LASER HAZARD	12:18
14:41	FAC	Kim	LVEA	Y	Tech Clean	15:50
15:34	VAC	Jordan	LVEA	Y	CP1 checks	15:43
15:53	SPI	Jennie	LVEA	Y	Unshutter SPI laser	15:56
16:10	FAC	Kim	LVEA	Y	Tech clean	17:01
16:22	SUS	Jennie	LVEA	Y	Open light pipe, IOT1 work, light pipe closed at 1700	17:00
16:40	SEI	Jim, Arnaud	LVEA	Y	BSC2 cabling, 1 person in-chamber	18:29
17:00	SPI	Shoshana	LVEA	Y	H2 enclosure to HAM3 parts shuffle	18:09
17:06	PEM	Robert	EndX	N	Grounding study	18:20
17:13	SUS	Ibrahim, Betsy	LVEA	Y	BS pitch adjustment in-chamber, by HAM3 checks, Betsy out 1830	18:49
17:24	SUS	Oli, Camila	LVEA	Y	Help alignment team by HAM3	18:46
17:33	OPS	RyanS	LVEA	Y	Bring Dust monitor to BSC2 crew	17:50
17:57	VAC	Gerardo	LVEA	Y	Inspect viewports, input/output tube	18:20
18:00	ISC	Keita	LVEA	Y	Talk to HAM3 crew	18:42
19:02	SUS	Oli	LVEA	Y	Move a chassis	19:10
19:48	PEM	Carlos, Shrey	Site	Y	Huddle test at vertex	20:54
19:49	PEM	Robert	Site	N	Searching for a seismometer	20:54
20:00	CDS	Patrick	Ends	N	Check on Beckhoff computers	20:22
20:13	SPI	Jeff, Jim	Optics lab, LVEA	Y	SPI work, optics lab then HAM3 at 21 UTC, Jim in at 2100, Jeff out at 2259	23:22
20:33	PSL	Betsy	LVEA	Y	Shutter PSL laser	20:40
20:35	VAC	Jordan, Gerardo	LVEA	Y	CP1 RGA scans and checks	22:55
20:40	SPI	Jennie	LVEA	Y	Search for a laptop	20:53
20:55	PEM	Robert, Carlos, Shrey	EndY	N	Retrieve seismometer	22:49
20:59	SPI	TJ	LVEA	Y	Join Jeff at HAM3 for SPI work	22:05
21:00	ISC	Betsy	LVEA	Y	Progress checks	21:26
21:05	SUS	Oli, Fil	LVEA	Y	Plug in chassis for BS	21:28
21:22	CRS	Shoshana, Michael	LVEA	Y	CRS work by HAM3	Ongoing
22:04	SQZ	Camilla, Eric, RyanS+1	LVEA	Y	Beam profiling at HAM7, RyanS out at 23:10	23:15
22:05	CRS	Arnaud	LVEA	Y	Join CRS team	Ongoing
22:09	SUS	Oli, Ibrahim	LVEA	Y	BS work	Ongoing
22:14	SEI	RyanC	Ends	N	Reset VFD panels for HEPIs, EY then EX	23:04
22:28	SAF	CRS	LVEA	YES	CRS laser ON near HAM3	Ongoing
23:32	IAS	Jason	LVEA	Y	FARO auto OFF/ON	23:37
23:34	ISC	Betsy, Robert	LVEA	Y	Checks	Ongoing

21:43 UTC Small power glitch
- HEPI ETMX, ETMY WD tripped. The pump stations went down as well, they came back with no issues.
- ISI ETMX ST1, ST2 WS tripped

H1 SEI - BS CPS replugged

arnaud.pele@ligo.org — Mon, 22 Jun 2026 14:45:07 -0700

Author: arnaud.pele@ligo.org

Report ID: 90696

Jim, Arnaud

The x12 in-vac BSC2 / BS ISI CPS sensors were replugged to their feedthrough as per D1003079. Jim worked from the platform, verifying the signals were live with a cds laptop while I was plugging them in from the chamber. Before starting this work we turned on the interface chassis and had to power cycle corner 3 a couple of times before getting the -18V LED from the back panel to turn on.

Images attached to this report

H1 ISC - Comment to BS alignment, could see SQZ beam off ITMX fly-bys at AS Port

camilla.compton@ligo.org — Mon, 22 Jun 2026 14:15:20 -0700

Author: camilla.compton@ligo.org

Report ID: 90694

Ryan S and I went back to the ITMX and BS alignment of the best ITMX SQZ beam "fly-bys", we did not see them or any flashes again.

H1 AOS - BRS Thresholds Changed

michael.ross@ligo.org — Mon, 22 Jun 2026 14:04:41 -0700

Author: michael.ross@ligo.org

Report ID: 90693

I increased both BRS damping threshold defaults to stop the ringing behavior that we've seen after Beckhoff restarts. The defaults are hard coded into the BRS Beckhoff control under the follow lines:

H1_ISI_GND_BRS_ETMY_LOWTHRESHOLD: INT:=2000;(*~ (OPC : 1 : visible for OPC-Server) (OPC_PROP[0005] :3: read/write) (OPC_PROP[0101] :Lower Damping Threshold: DESC)*) H1_ISI_GND_BRS_ETMY_HIGHTHRESHOLD: INT:=4000;(*~ (OPC : 1 : visible for OPC-Server) (OPC_PROP[0005] :3: read/write) (OPC_PROP[0101] :Upper Damping Threshold: DESC)*)

I changed the LowThreshold from 800 to 2000 and the HighThreshold from 2000 to 4000.

H1 ISC - Comment to BS alignment, could see SQZ beam off ITMX fly-bys at AS Port

keita.kawabe@ligo.org — Mon, 22 Jun 2026 13:44:35 -0700

Author: keita.kawabe@ligo.org

Report ID: 90692

Found the ITMX alignment that sends IMC flashs all the way to AS camera AND the SQZ beam all the way to ISCT1

But, as of now, IMC flashes don't come back to ISCT1 at all, and SQZ beam only comes back to AS camera via ITMY reflection. PRM is misalilgned.

The ITMX alignment is very different from where I started but this is expected as we have moved PR3 by a large amount when we tried to center the IMC flashes on ITMX.

sqz -> SR chain -> BS-> ITMX -> BS -> PR-chain -> ISCT1

	before/after
H1:SUS-ITMX_M0_OPTICALIGN_P_OFFSET	-96/-125
H1:SUS-ITMX_M0_OPTICALIGN_Y_OFFSET	104/-331

In the attached video (PXL_20260622_203143545TS~2.mp4), ITMY is misaligned and only ITMX reflection reaches two cameras. In the ISCT1 REFL camera you can see a big bright beam which is from SQZ, while in the AS camera you can see IMC flashes.

What we should do is to refine ITMX alignment such that we can see ITMX reflection of IMC flashes in ISCT1. After that, if the IMC flashes arestill visible in AS camera, scan BS alignment to find ITMY reflection of IMC flashes in ISCT1. If the flashes are not visible in AS camera, we need to do some math.

Images attached to this report

Non-image files attached to this report

PXL_20260622_203143545TS~2.mp4

H1 ISC - BS alignment, could see SQZ beam off ITMX fly-bys at AS Port

camilla.compton@ligo.org — Mon, 22 Jun 2026 12:38:05 -0700

Author: camilla.compton@ligo.org

Report ID: 90691

Betsy, Ibrahim, Oli, Keita, Camilla. Follow from 90665 where we left ITMY and SR2 in a strange location.

Summary: With ITMs back to top mass osems and BS at (P 1000, Y 1290), we have seen fly-by of SQZ beam of ITMX at AS port. Expect BS is moving to much to get steady beam. SR2 alignment very different than March/O4 (+500urad P, +150urad Y).

9am. We started by putting ITMs, SRM, SR2, SR3 back to March DRMI time sliders (11:02 PDT 19 March 2026), attached sliders. We did not like that ITM PIT top mass osem sensors were far from the March time (-30urad for ITMX, +220urad ITMY).

We tried adding -170 to the ITMY Pitch slider as per 90551, this still took us very far form the osem sensors.

9:33am We took ITMs, SRM, SR2, SR3 back back to the sensors (top mass osems) in March DRMI time (11:02 PDT 19 March 2026), attached sliders of this.

We then misaligned SRM but did not get our SQZ beam back on AS_A,B or AS_AIR camera off ITMY. We then went back to the time Thursday we had the beam on the camera at the current ITMY pitch pointing, moved according to osems for SR2 and oplev for SR3 (as HAM5 moved Thursday late afternoon 90671). Got the SQZ beam from ITMY back on the camera as per last Thursday, but this time we are happy with out ITM pointing.

We started the /ligo/home/sheila.dwyer/SUS/BS/BS_raster.xml but still could not see sign of SQZ beam off ITMX. BS was at (P 1000, Y 1000)

10:15am Went into HAM4 and moved BS sliders to get SQZ beams on top of each other: (P 1000, Y 1290). This is encouraging that even with a different ITMY position, the BS pointing is very similar to last week. Sliders attached.

On AS_A and AS_B we could see intermittent flashes of the SQZ beam off ITMX as it hit the sensors, we could also see it "fly-by" on the AS_AIR camera. We moved BS in a few 100's of counts and ITMX in ~100urad counts to try to improve this, it was intermittent (more flashes when there was more activity in the changer and when BS was not damped) but we did not improve it. Our best fly-bys are attached, typical good flashes also attached, amplitude of flashes as are expected. We'd later like to go back to this alignment.

We tried using SR2 to center ITMY SQZ beam on AS_AIR camera but the beam quality got worse we we reverted. Expect there’s a better SRC alignment could find, currently SR2 slider is ~ 500urad different than March!

Images attached to this report

H1 SPI - Comment to SPI install update - day 6

thomas.shaffer@ligo.org — Mon, 22 Jun 2026 10:08:18 -0700

Author: thomas.shaffer@ligo.org

Report ID: 90690

More details regarding the baffle installation:

When placing the below table baffle brackets, there was a ballast mass baffle (D1700262) that was blocking the angle bracket for the furthest -Y bracket. The bracket could not slide under the ballast mass baffle (bmb), so we decided to move the bmb in the +Y direction a few inches and I had to loosen the baffle panel within the feet to slide it up a few mm and then reclamp. This allowed the bracket to slide under the baffle just to the side of the feet, but the move partially exposed a corner of the shiny ballast mass stack.

The lower baffle shroud that covers the breadboard needed the fiber spools to be moved. We moved them over one set of bolt holes, but they are quite close to chamber edge, I'd guess around 1/2". Jeff then centered the two aperatures to the SPI beam, and we called it good. We still need to B&K the whole area.

Images attached to this report

H1 CDS - h1crsproc model running on h1seih23

david.barker@ligo.org — Mon, 22 Jun 2026 10:00:01 -0700

Author: david.barker@ligo.org

Report ID: 90689

WP13318 h1crsproc model install

Shoshana, Arnaud, Jim, Jonathan, Erik, EJ, Ryan C, Dave:

We installed the first version of the h1crsproc model on h1seih23 at 09:27 Mon22jun2026PDT. Because this took one of the two spare cores on this W2245 machine, this required a reboot to force the exception to this rule. We will upgrade this machine to a W3323 before the RGC/IPC upgrade.

A DAQ+EDC restart was needed, no major issues were found.

H1 SEI - CRS Transport to Chamber Side and Other Updates

shoshana.apple@ligo.org — Mon, 22 Jun 2026 09:54:22 -0700

Author: shoshana.apple@ligo.org

Report ID: 90652

[Shoshana]

Craned the CRS over to the temporary clean room over by HAM3 on 6/18. Unfortunately the flexures (SN13,SN20) broke during the transport process. It seemed like a clean break that was potentially caused by the proof mass jolting upwards crushing the flexures (photos attached), and the locks remained in place.

CRS was re-suspended chamber side HAM3 with flexures SN15/SN19, which is the last of the approved flexures of the first batch, but the other batch is ready for pickup. Suspension was painless as the locks kept the proof mass centered even after the break. The CRS CoM was balanced by eye.

There isn't an easily accessible outlet near the temporary clean room, so I was unable to get a resonance frequency measurement on Thursday. The hope is that because the proof mass remained locked when the flexures broke, the HoQI should hopefully still be mostly aligned with the CRS and only need small adjustments which will be done this week.

SEI

Images attached to this report

H1 ISC - Comment to Using SQZ to check BS alignment

betsy.weaver@ligo.org — Mon, 22 Jun 2026 09:46:36 -0700

Author: betsy.weaver@ligo.org

Report ID: 90688

This was supposed to say

SR3 - Use OPLEV pointing from THUR 5pm (when ISI came back on)

LHO VE - Purge Air Dewpoint Check (6/19/26)

jordan.vanosky@ligo.org — Mon, 22 Jun 2026 09:20:46 -0700

Author: jordan.vanosky@ligo.org

Report ID: 90687

Late entry from Friday night.

Jordan, Gerardo (remote), Betsy (remote)

On Friday night (6/19) Gerardo noticed the purge air dewpoint had risen above our -40C requirement and continued to rise. Out of precaution, I came on to the site to check the purge air status and see if any HAM/BSC door covers had blown off the flange.

All door covers were in place, so no issue there. I then isolated the purge air from the lvea for ~30 minutes, therefore dropping the demand/duty cycle of the air comporessor, to see if the dewpoint changed. It slowly began to drop and I took local dewpoint measurements at the sample port just past the filters on the purge air skid. There was no significant difference in dewpoint when the drying towers cycled, the dewpoint remained around -38C regardless of which tower was drying.

After ~30 minutes, the dewpoint had dropped to -43C and so I reopened the purge air to the lvea, then reduced the flow at the purge air port on the output tube. It seems there was just too much demand on the compressor.

As of this morning, the dewpoint has returned to normal -51C at the drying towers.

Images attached to this report

H1 General - OPS Monday Day shift start

ryan.crouch@ligo.org — Mon, 22 Jun 2026 07:34:23 -0700

Author: ryan.crouch@ligo.org

Report ID: 90686

TITLE: 06/22 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: MAINTENANCE
Wind: 17mph Gusts, 10mph 3min avg
Primary useism: 0.04 μm/s
Secondary useism: 0.09 μm/s
QUICK SUMMARY:

HAM7 work, CRS work, possibly more FARO HEPI alignment planned for today
IFO alignment checks

H1 CDS - Comment to PID control of CP1 pump LN2 level looking good

david.barker@ligo.org — Mon, 22 Jun 2026 07:14:08 -0700

Author: david.barker@ligo.org

Report ID: 90685

Here is the last two days trends, CP1 LN2 level is holding at 92.00 +/- 0.05 %

Images attached to this report

H1 ISC - Comment to Measurement of jitter with IMC WFS at 10W

jennifer.wright@ligo.org — Sun, 21 Jun 2026 23:30:43 -0700

Author: jennifer.wright@ligo.org

Report ID: 90684

Just adding a note with the comparison I used for my GWADW talk on May 19th so its in the alog.

I did an injection into the yaw DOF of the PZT mirror in the PSL and measured the response on the IMC REFL QPD DC when locked, since this was used to do jitter injections to produce noise plots during O4 I could compare to a time when we did this measurement during NLN without JAC, and locked at 10W with JAC.

The power difference shouldn't matter since I am doing a transfer function, but unfortunately the injection I did was not high enough to see coherence in the IMC REFL WFS QPDs and I ran out of time to repeat the measurement in March due to corner re-alignment efforts.

The two times I chose were:

60W lock without JAC: 07-08-2025 21:47:59 UTC - approx 16 minutes.

2W lock with JAC: 18-03-2026 22:28:12 UTC - approx. 16 minutes.

The graph which compares WFS B QPD with old measurement in blue and new in orange can be used to put a lower limit on the suppression of JAC. It gives a minimum jitter reduction of 0.15 at 10Hz.

I would like to redo this once we pump down the corner sufficiently to do some measurements with the main laser.

The txml measurement files that contain the data I used for this are in /ligo.home/jennfioer.wright/git/2026/JAC/JAC_PZT_Y_inj.xml for the new measurement and the same folder but the file 20250807_IMC_WFS_PZT_Y.xml for the older measurement.

Images attached to this report

H1 CDS - PID control of CP1 pump LN2 level looking good

david.barker@ligo.org — Fri, 19 Jun 2026 07:37:53 -0700

Author: david.barker@ligo.org

Report ID: 90683

Using the same settings as 2021 the PID control of CP1's level is maintaining the 92% setpoint nicely.

Images attached to this report

H1 SPI - Comment to SPI, Pathfinder Install, REF Beam error found

jeffrey.kissel@ligo.org — Thu, 18 Jun 2026 19:51:31 -0700

Author: jeffrey.kissel@ligo.org

Report ID: 90682

The sawtooth that Josh mentions was how the poorly phased analog versions of the 4096 Hz SIN and COS LO signals manifested on the digitized versions of the IFO PD voltage, reading out that beatnote. Here, I attach what it looked like on the o-scope (before discovering the issue of phasing the two SIN and COS versions of the LO).

Images attached to this report

H1 ISC - Comment to Using SQZ to check BS alignment

betsy.weaver@ligo.org — Thu, 18 Jun 2026 18:46:54 -0700

Author: betsy.weaver@ligo.org

Report ID: 90681

The pic of the beams is from before I started the mech pitch adjustment but had Yaw aligned via the slider.

Images attached to this report

LHO VE - Comment to CP1 Cooldown Started

gerardo.moreno@ligo.org — Thu, 18 Jun 2026 18:41:05 -0700

Author: gerardo.moreno@ligo.org

Report ID: 90677

(Jordan V., Travis S., Gerardo M.)

CP1 cooldown re-start, apparently one or both of the valves did not respond as they should have, either the "bottom draw" and the "bypass" valves did not open yesterday, or one of them did not open, do not know which.

This morning I opened the valves in a different manner, and paid close attention to their behavior, the "bottom draw" valve made a small pop as I opened it, so I closed the valve and then opened it again, I had to do that about 3 different times, the last time there was no pop, it seems as if the valve was letting go of the sealing component, on the third attempt I was able to hear the LN2 rush thru. Same for the "bypass" valve, opened it with care and paid attention to the sounds it made, no pops noted, but to make sure I opened and closed the valve 3 times, never opening it more than 1/2 turn. Then set it the same way as yesterday, the guestimate of 10% open, about 0.8 turns. Then I was able to hear the nitrogen gas out of the exhaust line. Left CP1 and went to check on the progress via MEDM screens and plots. Soon we had the first numbers on the pump level % full, we started with a very tiny number but little by little the cryotrap started to fill. Because of the experience of with the above mentioned valves I decided to actuate early the LLCV, but only opening it up to 2%, eventually with time and two cell phones I was able to note that the LLCV was indeed actuating good. Soon the 85% came along and it was time to hand over the controls to the PID, which it did not have any issues, well 1 issue, the 15% output low limit was to high, the PID railed, so I lowered it to 10%, this number will be assessed on the upcoming days to see if we leave it or not. We left the RGA scanning during and post the cryotrap cooldown.

Vacuum pressure in CP1 has dropped and currently we are at 3.8x10^-09 Torr, from about 4.0x10^-08 Torr this morning.

The consumption of LN2 was good, the dewar dropped about 2.24% to fill the cryotrap.

The turbo pump continues to pump on the system and it will until we reach at least 1.0x10^-09 Torr or better.

Images attached to this report

H1 SPI - SPI install update - day 6

jennifer.wright@ligo.org — Thu, 18 Jun 2026 18:39:17 -0700

Author: jennifer.wright@ligo.org

Report ID: 90676

Jennie W, Jeff K, Josh F, TJ S,

Summary: SPI interferometers aligned, shroud installed successfully. One stray beam and possible clipping on shroud to investigate/deal with but otherwise all problems were solved. Obligatory success photo taken by Josh.

Today we:

reseated the M_M5 mount in its holder. We had troubles with this stick-slipping when we tried to move it. Jeff replaced the 45 deg adaptor part D2400336-v4 S/N 001 type 1 with S/N 002. This seats better in the holder.
realigned beam to QPD A and B using picomotors M_C1 and M_M1.
Confirmed other two picomotors M_B4 and M_M2 work and their pitch DOF (in breadboard basis) matches left/right on picomotor controls.
We had some weirdness in the meas IFO which Josh has solved and will discuss in other alog from Josh (LHO alog #90680).
During this debugging we used the oscilloscope to plug into analog outputs for meas and ref IFO and a commercial RF source.
We used the breadboard steering mirrors to get 85.9 % heterodyne efficiency on the reference IFO PD A and 88.9% efficiency on reference IFO B.
With no adjustment the measurement interferometer PD A had 86% efficiency and PD B had 93.4% efficiency so we will take this (ch4 on scope is PD A, ch2 is PD B).
This afternoon we installed the shroud around the ISIK breadboard.
We had to move the fiber spools to avoid the bottom shroud bracket and these are now close to the edge of the beam tube where it meets HAM3 in the -x direction.
After installing the shroud panels both QPDs had dropped in power by ~2V, will investigate on Monday as the beam does not appear to clip the shroud when we check with the card.
There is also a stray beam from the FBR_PWRIN_REF PD that hits the upper shroud stand-off on the lower panel on the -y side and then hits the door cover, this will need dumped somehow.
After moving the fiber spools I checked the FBR PWRIN channel for meas and ref and these both drifted after we rerouted the fibre spools but the level seems to have been dirfting more than this since we got into chamber this afternoon at 14:20. The first cursor in the photo is when we started moving the spools and the second is when I shuttered the laser.

SEI

Images attached to this report

H1 SPI - SPI, Pathfinder Install, REF Beam error found

joshua.freed@ligo.org — Thu, 18 Jun 2026 18:10:20 -0700

Author: joshua.freed@ligo.org

Report ID: 90680

J. Freed

Found the problem discribed in 90644, as well as the strange sawtooth beat notes we have been finding in our IFOs. It was user error on our CDS system, the double mixer (which produces our REF RF signal for AOMs) requires a sin wave and cos wave 4096Hz signal. We were sending it 2x cos signals.

This also explains why our demod systems were not working as they use the same signals.

CDS_Sin_and_Cos.jpg Shows that they were the same signal

REF_RF_Before.jpg REF_RF_After.jpg Shows the REF signal before and after. The before had a 4096Hz beat note inside itself

MEAS_IFO_BEAT_After.jpg Shows the corrected beat note on the Meas IFO after the correction. Note: There is some noise here which is partly caused by 16kHz signal that is ~13dB less than the main signal. The double mixer produces this as a byproduct and SPI is insensitive to this noise.

Images attached to this report

H1 ISC - Comment to Using SQZ to check BS alignment

betsy.weaver@ligo.org — Thu, 18 Jun 2026 17:25:14 -0700

Author: betsy.weaver@ligo.org

Report ID: 90679

Sheila, Oli and I worked on mechanically adjusting Pitch of the BBSS (BS) to bring the ITMs closer together in pitch as seen via their SQZ beams in front of PR2. In the end, I adjusted the BBSS PUM pitch adjuster ~2 full turns (after some more iterating) to get the ITM beams ~on top of each other (our better touching instead of inches apart). At some point it got harder to land the beams right on top of each other as I kept walking over the sweet spot so we moved over to using the sliders. I thought we had the slider values at ~1000 on each PIT and YAW when we left the chamber around 2:30pm PT. However now that we have moved back into the controlroom we have fallen down a few side quests and are a bit confused on what alignments are good and what aren't. So, I think we will need to revisit all of the alignment again starting next week.

Side Quest 1 - In order to refine our initial conditions alignment, Camilla and Elenna started looking closer at the ITM and SR2 slider values which were moved earlier in the day to get the SQZ correct on the AS_AIR. This was confusing since the ITM oplevs likely dropped off when we vented. Then, Anamaria pointed them ~Jun 2 90485 in order to monitor FC and baffle work, but then also they were different a month ago. These biases could be turned off to restore the "IFO pointing" but then we will be blind to the OPLEVs. So, this needs more study.

Side Quest 2 - I brought the HAM5 ISI state to Jims attention today - Jim found that HAM5 had some issues with some sensor electronics being off at the rack for the last 50 day (since April 29th) so fired that up and got the ISI back into the correct state. This moved the beam alignment Elenna and Camilla were in the middle of, so Camilla put the SR3 back to the oplev to restore the beam on the AS_AIR again.

Side Quest 3 - The BBSS sliders are badly cross-coupled in PIT and YAW - we see the beam move diagonally when moving them. LLO is newly reporting this as well. On the test stand there was no Tom, Oli and Ibrahim are looking into this - at the moment they are measuring which of the QOSEMs are firing up when requesting YAW and PIT, so the sliders are on the move. This needs more study.

So, the good news is that we have a process to view the IFO corner alignment in order to confirm/tweek the BBSS.

However because of the above and the factors which mean some SUSes have accurate OPLEVs and some don't, we will need to restart on Monday with repointing the ITMs and then revisit the SQZ beam at PR2.

SR2 - Use OPLEV pointing from THUR 5pm (when ISI came back on)

ITMs - Turn Anamaria biases off then restore to OSEMs from DRMI (?)

H1 SPI - Comment to Parts added to seiproc for HAM2-3 and HAM4-5 differential supersensor comparison,

erik.vonreis@ligo.org — Thu, 18 Jun 2026 17:22:40 -0700

Author: erik.vonreis@ligo.org

Report ID: 90678

Adding png

Images attached to this report

H1 SPI - Parts added to seiproc for HAM2-3 and HAM4-5 differential supersensor comparison,

jim.warner@ligo.org — Thu, 18 Jun 2026 17:21:32 -0700

Author: jim.warner@ligo.org

Report ID: 90675

I've been talking to Jeff about changes to the ISI and seiproc models for SPI and CRS integration. The ISI models are pretty much done, but today I added a parts to seiproc to take HAM2345 cps and gs13 cart channels and blend them to create cartesian differential supersensor channels. The idea being these will be good metrics for determing if SPI is actually improving the differential ISI motion. Plan is to use blend filters to combine the cps and gs13 pairs from each chamber to make supersensor channels, and then compare the differential supersensors for HAM2-3 to the differential supersensors at HAM45. I've checked that seiproc builds with these changes, but I now have some changes to make to the HAM45 models and some ipcs to make. And then a whole bunch of medm work.

Erik had to attach my screen shot, because firefox is not cooperating in the control room for me, but it shows a snippet of the flow in the ISI_DIFF block in seiproc and the channels I think Jeff wants to save. We didn't talk about data rate, so that's just a guess.

MDL/SIM

H1 CDS - CPs all green

david.barker@ligo.org — Thu, 18 Jun 2026 16:42:46 -0700

Author: david.barker@ligo.org

Report ID: 90674

Images attached to this report

H1 General - OPS Thursday Day shift summary

ryan.crouch@ligo.org — Thu, 18 Jun 2026 16:30:48 -0700

Author: ryan.crouch@ligo.org

Report ID: 90672

TITLE: 06/18 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY: BBS checks, SPI, and CRS work continued. (Covering the end of day for TJ).
LOG:

Start Time	System	Name	Location	Lazer_Haz	Task	Time End
20:18	SAF	LVEA IS LASER HAZARD	LVEA	YES	LVEA IS LASER HAZARD	12:18
15:44	SPI	Jeff, Josh	LVEA	Y	SPI HAM3/2 work	18:58
15:58	SPI	Jennie	LVEA	Y	SPI HAM3/2 work	18:58
16:01	CRS	Betsy	LVEA	Y	Checking on chamberside test site for CRS	16:26
16:26	SEI	Jim, Randy, Shoshana	LVEA	Y	Crane and move CRS from H2 to next to HAM3	17:10
16:52	VAC	Travis	LVEA	Y	Removing the old ISI oplev viewports on input and output arms	19:01
16:58	SUS	Ryan C	CR,EX,EY	n	SUS oplev charge measurements	18:58
17:35	SEI	Fil, Jason	LVEA	Y	Looking at the ISI oplev setup with Travis	18:21
18:08	SEI	Shoshana	LVEA	Y	CRS work near HAM3	20:25
18:37	VAC	Gerardo	LVEA	Y	Helping removing viewport by HAM2	20:02
18:59	SPI	Josh	LVEA	Y	SPI electronics racks	20:36
19:15	SUS	Betsy, Camilla	LVEA	Y	Going into HAM3, BSC2. Camilla out 20:45	21:38
20:14	SUS	Sheila	LVEA	Y	Swap in for Camilla	21:38
20:21	SPI	Jennie	LVEA	Y	Looking for shroud parts	22:32
20:21	SPI	TJ	LVEA	Y	Installing shroud	Ongoing
20:25	SPI	Jeff	LVEA	Y	SPI work	22:32
20:39	SUS	Oli	LVEA	Y	HAM3/BSC2 checks	21:38
20:52	SUS	Tom	LVEA	Y	Join BBS team	21:59
20:57	SUS	Camilla	LVEA	Y	Grab stuff	20:58
21:30	FAC	Randy, Ibrahim	LVEA	Y	Move a scissor lift, find ameristat wrapper	21:43
21:38	EPO	Elenna, Deon, Matilda, Shrey, Khanh	LVEA	Y	Tour the LVEA	22:34
21:42	VAC	Travis	LVEA	Y	Viewport swap continued	23:20
21:51	VAC	Gerardo	LVEA	Y	CP1, check out pipes	21:58
22:01	SPI	Josh	LVEA	Y	SPI work at SUS R2 rack	Ongoing
22:25	SPI	Betsy	LVEA	Y	Check on SPI crew	22:35
22:37	SUS	Ibrahim, Tom, Deon, Oli	LVEA	Y	BSC2 cross coupling investigation and tour	23:34
22:43	SEI	Jim	LVEA/CR	Y	Diagnose HAM5 rack sensor signals	23:25

LHO VE - Unused HAM ISI Oplev viewports removed

travis.sadecki@ligo.org — Thu, 18 Jun 2026 16:26:48 -0700

Author: travis.sadecki@ligo.org

Report ID: 90673

Today Gerardo and I removed the unused HAM ISI Oplev viewports from the VP7 ports of both the -X input manifold and the +Y output manifold. The ports were blanked off with 10" CF blanks. I noted a series of 3 scratches on the angled flat of the flange, but the knife edge itself wasn't noticeably deformed. See pics.

Note to VAC: These will need to be leak checked during pumpdown.

Images attached to this report

H1 TCS - Comment to Adding CO2 annular heating simulation

evan.hall@ligo.org — Thu, 18 Jun 2026 16:02:16 -0700

Author: evan.hall@ligo.org

Report ID: 90669

TJ, Camilla, Evan

With some difficulty I was able to extract the annular mask design data from D1201477. One can piece together that the CO2 beam size at the mask is nominally 10 mm and is more or less at a waist (LHO:76715), which is consistent with some crude finesse beam propagation based on T2200035, although one has to fudge the location of the 1.2 mm beam waist out of the CO2 laser. Aidan measured 10 mm at Livingston, too (LLO:14419).

The first attachment is a simulation of the intensity pattern immediately after the mask, with the nominal 22.5° horizontal angle applied to the mask. The in-air CO2X table is supposed to image the mask onto the CP with about a 23× magnification factor, so the aperture (imaged to the same plane of the mask) is indicated too.

The second attachment computes the radial intensity function and projects it to the CP, with the CP aperture again indicated. This plot is vaguely similar to Aidan's inferred intensity plot above (his horizontal units are presumably supposed to be meters, not millimeters). These intensity patterns are very different from the final design document and from the TCS overview paper from 2016, where the goal there was to cut off the intensity above 10 cm or so at the CP.

ISC

Images attached to this report

Non-image files attached to this report

annular_CO2_mask_D1201477_intensity_CP.pdf

H1 SEI - HAM5 ISI interface chassis was off since Apr 29 2026, turned back on now

jim.warner@ligo.org — Thu, 18 Jun 2026 15:56:26 -0700

Author: jim.warner@ligo.org

Report ID: 90671

Betsy said they couldn't isolate HAM5 while trying to find beam in the output arm. When I opened the overview, I saw that all of the corner 2 sensors were all 0. I went to the CER and found that the corner2 interface chassis was turned off. Turned that back on, HAM5 can isolate now. They tend to work better with all of their sensors.

H1 CDS - CP1 LN2 Level Sensor Fixed. CP1 under PID control and alarms have been restored.

david.barker@ligo.org — Thu, 18 Jun 2026 15:53:22 -0700

Author: david.barker@ligo.org

Report ID: 90670

At 15:03 Gerardo switched CP1 level control from manual to PID. We verified that the PID settings are still as they were when the LN2 level sensor stopped working on 5th August 2021.

I have added a ndscope trender which shows the pump level and the PID LLCV control value cp1_1_day_trend

CP1 pump level control alarms were restored to the alarms system, alarm level set to <= 85% and >=99%.

--- h0ve_configuration.xml (revision 7482)
+++ h0ve_configuration.xml (working copy)
@@ -9,30 +9,26 @@



-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
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-
-
-
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-
-
+<Channel name="H0:VAC-LY_CP1_LT100_PUMP_LEVEL_PCT" low="8.5e+01" high="9.9e+01" description="CP1 Pump LN2 Level">
+ <Contact address="5094380824@vtext.com" hot="15" cool="5" description="C:Richard McCarthy"></Contact>
+ <Contact address="5094380826@vtext.com" hot="15" cool="5" description="C:David Barker"></Contact>
+ <Contact address="5094380828@vtext.com" hot="15" cool="5" description="C:Gerardo Moreno"></Contact>
+ <Contact address="2083011360@vtext.com" hot="15" cool="5" description="C:Travis Sadecki"></Contact>
+ <Contact address="rjmcc@caltech.edu" hot="5" cool="2" description="E:Richard McCarthy"></Contact>
+ <Contact address="dbarker3@caltech.edu" hot="5" cool="2" description="E:Dave Barker"></Contact>
+ <Contact address="gmoreno@caltech.edu" hot="5" cool="2" description="E:Gerardo Moreno"></Contact>
+ <Contact address="tsadecki@caltech.edu" hot="5" cool="2" description="E:Travis Sadecki"></Contact>
+</Channel>
+<Channel name="H0:VAC-LY_CP1_LT100_PUMP_LEVEL_PCT_ERROR" low="-5.0e-01" high="1.0e+00" description="CP1 Pump LN2 Level ERROR">
+ <Contact address="5094380824@vtext.com" hot="15" cool="5" description="C:Richard McCarthy"></Contact>
+ <Contact address="5094380826@vtext.com" hot="15" cool="5" description="C:David Barker"></Contact>
+ <Contact address="5094380828@vtext.com" hot="15" cool="5" description="C:Gerardo Moreno"></Contact>
+ <Contact address="2083011360@vtext.com" hot="15" cool="5" description="C:Travis Sadecki"></Contact>
+ <Contact address="rjmcc@caltech.edu" hot="5" cool="2" description="E:Richard McCarthy"></Contact>
+ <Contact address="dbarker3@caltech.edu" hot="5" cool="2" description="E:Dave Barker"></Contact>
+ <Contact address="gmoreno@caltech.edu" hot="5" cool="2" description="E:Gerardo Moreno"></Contact>
+ <Contact address="tsadecki@caltech.edu" hot="5" cool="2" description="E:Travis Sadecki"></Contact>
+</Channel>

Images attached to this report

H1 AOS - aLIGO BS Surveying - In-Chamber and Test Stand

jason.oberling@ligo.org — Thu, 18 Jun 2026 15:06:03 -0700

Author: jason.oberling@ligo.org

Report ID: 90156

J. Oberling, R. Crouch, J. Warner, B. Weaver, I. Abouelfettouh, O. Patane, S. Appert

And finally, here is the long-promised alog for our full set of measurements of the now-deinstalled aLIGO BS. I will give a brief overview of the WBSC2 support tube and BS in-chamber measurements we took, but the bulk of this alog will concern the various test stand measurements we took and how they tie in to the in-chamber and support tube measurements. As a reminder, our alignment tolerances for the aLIGO BS were:

Relative to IAS equipment (set normal to the AR surface of the optic)
- Horizontal: +/- 1.0 mm
- Vertical: +/- 1.0 mm
- Longitudinal: +/- 3.0 mm
Relative to IFO axes
- X: +/- 2.8 mm
- Y: +/- 2.8 mm
- Z: +/- 1.0 mm
Pitch: +/- 55 µrad
Yaw: +/- 190 µrad

Strap in folks, this is going to be a long one with a wall of text. But first, I demand... A shrub, errr, a summary!

Summary

Earlier this year we measured the location of the ends of the WBSC2 support tubes. They indicated a -X translation of the WBSC2 cartridge and a CCW yaw. But, since the support tube length wasn't a controlled dimension for support tube construction we can't use them to definitively inform us about the cartridge assembly in the chamber (we've measure 4 tubes so far, and all 4 have been different lengths by several mm). The -X translation was a little surprising because we translated the cartridge in the +X direction during our 2013 install, implying that the support tubes were already sitting too far in the -X direction. The CCW yaw wasn't surprising since we yawed the cartridge CCW back in 2013.

At first we thought the in-chamber alignment looked pretty good, it was only after the cartridge had been removed from the chamber that we realized the mode we had used to make the measurements had a high potential to disguise positional deviations and make the measured point look closer to nominal than it actually was (see the in-chamber section below for full details). The decision to use this mode was made during our planning for the alignment (it's in our alignment procedure), and was based on an incomplete understanding of how the underlying mode actually worked. Well, now we know better, but unfortunately the consequence is that we cannot say how well the BS was aligned to the IFO XYZ coordinate system. What we can say is that the BS was clearly yawed in the CW direction w.r.t. the SUS cage, by potentially several mrad, but have no insight into how it was yawed w.r.t. the IFO XYZ axes.

On the test stand, we found the BS SUS to be right on the edge of our position tolerances for the optic. We never measured the SUS cage back in 2013, so this was the first time we had looked at it. The optic itself was found to be within our position specs, but we did measure the position to be in a different place than we did in 2013. We traced this primarily to 2 things: The large +/- 2.0 mm error bar in the total station's distance measurement mode (used to set the optic's longitudinal position in 2013) and errors in the position of the test stand's brass monuments (used to place the alignment equipment in 2013). We were able to trace this using the FARO, using its much higher accuracy to measure both the BS longitudinal position and the test stand monuments. We did find that the pointing of the BS was well outside of our specs: pitch was ~200 µrad up while yaw was ~710 µrad CW. While the pitch being out of spec after the cartridge was craned was not surprising (looking back through my aLIGO install notes we never had a pitch alignment survive craning into a chamber), we were surprised at the yaw measurement. The mispositioning of the test stand monuments did not explain this yaw, and we could find no obvious cause.

WBSC2 Support Tubes

The WBSC2 support tube ends were surveyed with FARO earlier this year. From talks with Jim, my understanding is that support tube length was not a critical dimension for tube construction, and so far this is holding up. We've measured the support tube ends for WBSC2 and WBSC3 so far (more to come as we're able), and the lengths have not been constant (the WBSC3 support tubes measured short of their design length, and each one was a different length, while both WBSC2 support tubes measured longer than their design length). Because of this, we can't give any definitive numbers about the respective cartridges, but the info does offer some general guidance. For WBSC2 this is:

The cartridge was shifted in the -X direction (towards the PSL) by a couple mm
- This is odd, as the old notes from WBSC2 installation in 2013 indicate that HEPI was shifted +X by over 4 mm
  - That said, the +X shift makes sense (the direction, not the exact number), see test stand section below
- Only explanation I have is a guess that the support tubes were not well located before cartridge install; I have no knowledge of how the aLIGO SEI install team set the support tubes before the cartridge was installed, so I have no data to back up this guess
The cartridge was rotated couterclockwise (CCW) when viewed from the top down by up to 1.3 mrad
- My notes from the in-chamber pitch/yaw alignment back up the direction, as we initially requested a 400 µrad CCW yaw shift be done via HEPI

The important thing to note here, in my opinion, is the CCW yaw (again, the direction, not so much the exact number). This will be important later on, once we get to the test stand measurements.

aLIGO BS In-Chamber

We took a series of measurements on the BS while in the chamber in mid-April, see the alog for more detail. Some important takeaways, in my opinion:

Due to the construction of our rods, as they are not repeatable in X and Y, we do not have a good idea of where the WBSC2 ISI optics table is w.r.t. the IFO X and Y axes (this will only be an issue with WBSC2, since for the other 4 BSC chambers we can set FARO right outside the open door and measure the ISI directly)
- Averaging out the 7 Z axis deviations, the ISI is sitting too high by ~0.1 mm (average is -2.8 mm, and it should be -2.9 mm since this ISI should be lower by that amount to place the BS at the correct Z axis position; this wasn't corrected in CAD, hence the listed deviations)
The SUS cage appears well positioned w.r.t. the IFO axes
- Although I now question that, given the large potential for misreads of the Build/Inspect mode's results, but it's the info we have and we cannot measure it again
  - In future, we will not be using the Build/Inspect mode; its ease of use is attractive, especially for quick measurements, but we have found it to be error prone due to its automatic SMR radius compensation (explained in the paragraph immediately following these bullet points)
Ruler measurements show the BS optic is well positioned w.r.t. the SUS cage
- When looking directly AT the HR surface, it's sitting ~0.25 +/- 0.25 mm to the left, ~0.25 +/- 0.25 mm low, and ~0.7 +/- 0.7 mm too close to the HR Figure 8 section of the SUS cage
  - The error bar on the longitudinal measurement is large due to how the measurement had to be made, as explained in the 2nd comment to the in-chamber alog linked above
- Rotating this to the IFO axes gives:
The BS optic is yawed w.r.t. the SUS cage
- Betsy said this was visible by eye
- Ruler measurements from the lower Figure 8 of the SUS cage to the BS HR surface indicate this yaw is in the CW direction, but the error bar for this measurement is so large that the amount of yaw is largely unknown
  - Test stand measurements shed more light on this yaw

Because we used the Build/Inspect mode with the automatic SMR radius compensation turned ON to measure the BS SUS position in-chamber, we unfortunately do not have a good idea of where the SUS was located within WBSC2 and by extension do not have a good idea of where the BS optic was positioned. Subsequent testing after the cartridge had been removed from the chamber showed that we did not have a good understanding of how the automatic SMR compensation worked. Short version: It's dumb. It simply compensates in the direction of the measurement object, regardless of where your measured point is. For example, you're measuring a point on the the underside of a horizontal plate with Build/Inspect mode. The SMR would sit below this plate in the -Z direction, so the SMR radius should be compensated in the +Z direction. The automatic compensation does not compensate in the +Z axis alone, it compensates directly towards the nominal point. This then can result in a measurement that looks dead on but in fact could be nowhere close; if the actual point is off several mm in the X and Y directions, the automatic compensation would make the resulting measurement look like it was dead on as it compensates towards the measurement object, removing the actual deviations in the process. The final attached picture is a drawing showing this behavior. We finally noticed this while testing the FARO test stand alignment procedure on an old HAM passive stack after the BS cartridge was removed, and then confirmed it while aligning the BBS SUS on the test stand; initial BBSS placement was done via Build/Inspect as a real time feedback, but we measured the points using a more involved method that tells PolyWorks what direction to compensate in instead of letting the software do it automatically. The measured points were several mm off of the Build/Inpsect points, and we confirmed the automatic compensation was the cause by turning it on and off (when automatic compensation was turned off, Build/Inspect reported deviations that matched our direct measurement of the alignment points).

aLIGO BS Test Stand

FARO Measurements

And now we come to the test stand meausurements. To start, we aligned the FARO to the ISI using 10 points on the ISI; these points and the resulting alignment are shown in the 1st attached picture, and show the FARO is well aligned to the ISI. Once the FARO was aligned to the ISI we then measured several points along the bottom of the SUS cage, as well as the center of both the HR and AR sides of the lower Figure 8 structure; this is shown in the 2nd attached picture. We did not measure the SUS cage position during aLIGO install, only the optic position, so it's good to see the cage is mostly in the neighborhood of the optic position tolerances. One note about the Z axis numbers shown here: The CAD model used here is the in-chamber model, which places the BS at its in-chamber Z axis coordinate of -82.9 mm. However, the BS SUS is the same length as the QUAD SUSs, so the BS is placed w.r.t. the ISI the same as the QUADs, i.e. at -80.0 mm; -82.9 mm was acheived in-chamber by lowering HEPI, but on the test stand the BS was aligned at -80.0 mm. This was never properly corrected for in the CAD model; I think the SUS cage itself and its components were lowered while the ISI was left at its nominal height, so all the Z axis measurements should show a deviation of around +2.9 mm (since they are physically higher than the CAD would indicate). This is seen most clearly with the HR and AR Figure 8 structure measurements. Both Z axis positions measured right around -80.0 mm as they should, while the CAD model claims they are too high. This has been corrected for in the BBS CAD model, so this is the only time we'll see this discrepancy.

The 3rd attached picture shows a set of lines created from the measurement points we took on the structure which show how the BS SUS cage is rotated w.r.t. the ISI; I also rotated the CAD model so that it matches the target yaw angle of the BS optic itself. The angles here are reported w.r.t. their respective positive axes (i.e. X Ang is the angle measured from the positive X axis). As can be seen, the SUS cage had a large CCW yaw w.r.t. the ISI. Averaging the various yaw deviations gives a yaw of the BS SUS w.r.t. the ISI of 0.2762°, or 4.82 mrad CCW. This explains the large CW yaw of the BS optic w.r.t. the SUS cage.

With those measurements done we then used the FARO to set a total station looking at the AR surface of the BS, set along the target AR surface normal so we can measure position deviations from nominal. Once we had these position deviations we moved the total station to the HR side of the BS, mounted a laser autocollimator (LAC) on top of it, set it along the target HR surface normal and offset by 150.0 mm (to avoid the test stand leg) to measure the pitch and yaw of the BS. The results were posted to the alog here, so the details follow below.

I should note here how we measured the longitudinal position of the BS AR surface. As noted above, we used the FARO to measure the circle that represents the AR side of the lower Figure 8 structure of the BS SUS; PolyWorks calculates the center of this circle, and is what is shown on the 2nd attachement with the label "BS_FIG8_AR". We also know the position of the total station, as we set that using the FARO. We then use PolyWorks to measure the distance between the total station and the BS AR Figure 8, as well as measure the target distance from the total station to the BS AR surface. We then measure the distance from the AR Figure 8 to the BS AR surface using a depth micrometer; this was done on the left, right, top and bottom of the Figure 8. These 4 measurements are averaged together to give us a distance from the Figure 8 to the BS AR surface, which is then added to the measured distance from the total station to the AR Figure 8. This final distance is compared to the target "total station to BS AR" distance to give us the longitudinal position deviation of the BS AR surface.

BS Position and Pointing

The original BS test stand alignment was completed in early February 2013. The below table gives the final position and pointing deviations we measured in 2013 and those we measured now; I've rotated the position deviations to the IFO XYZ axes for both. In 2013 we were on Test Stand #2 (currently disassembled due to filter cavity interference) and using pre-set brass monuments, and now we are on Test Stand #1 and using the FARO to precisely set the total station.

	2013 Test Stand	2026 Test Stand	Difference
X	+0.1 mm	-1.8 mm	-1.9 mm
Y	+0.1 mm	+0.8 mm	+0.7 mm
Z	+0.3 mm	-0.8 mm	-1.1 mm
Pitch	-20 µrad (up)	-200 µrad (up)	-180 µrad
Yaw	-10 µrad (CW)	-710 µrad (CW)	-700 µrad

That's, uh, quite the difference, yeah? A couple of things that should be noted here:

The 2026 pointing measurements, like the 2013 ones, were done with the alignment bias sliders OFF. With the alignment bias on we did not get a return in the LAC, as the beam was then too far in the CW direction. The yaw slider was set to -388 µrad, which is CW per SUS sign conventions, so the alignment sliders were pushing the BS further CW. This could be because of in-chamber yaw deviation, but we don't know for sure since the use of the automatic compensation in the Build/Inspect mode messed up the in-chamber measurements (as previously explained).
We, obvously, did not have a FARO in 2013, so were using the total station entirely for positioning. For the longitudinal position (position along the AR surface normal of the BS) we used the total station's internal distance measurement function, which has an error bar of +/- 2.0 mm. Keep this in mind, as in 2013 we measured a longitudinal deviation of 0.0 mm, while now with the more accurate FARO assisting our setup we measured a longitudinal deviation of +1.8 mm (within the +/- 2.0 mm error bar of the total station's distance measurement).

Despite the large difference in position deviations between 2013 and 2026, these are still within our set position specification. The pointing is decidedly not. While it's entirely possible that things have drifted in the 13 years since the BS was installed, there are 2 somewhat obvious things that would contribute to this difference: The total station's +/- 2.0 mm error bar for distance measurements and error in the placement of the test stand's brass monuments. We've already measured a difference in longitudinal position between 2013 and 2026 that is within the error bar of the total station's distance measurement, but what about the test stand monuments? Well, we used FARO to measure those.

Test Stand #2 Monuments

To measure the test stand monuments we first had to align the FARO to the test stand coordinate system. To do this, we used the set of monuments set along the XY axes of the stand and PolyWorks' Best-Fit Alignment routine (the same routine used to align the FARO to the ISI on the test stand); the test stand coordinate system was assumed to be flat along the floor and 2 dimensional (XY only), so I forced all of the Z axis nominals and measured to 0.0. The results of the alignment are shown in the 4th attachment. It's immediately apparent that our test stand monuments are not going to be where we thought they were, as the alignment routine was not able to fit a good alignment between the nominal and measured coordinates of the alignment monuments (the first attachment shows the results of the alignment routine when it can find a good fit between the nominal and measured data). We re-did this a couple times and got very similar results each time (to <0.1 mm), so the monuments are definitely not where we thought they were. We proceeded to use this alignment to measure the rest of the test stand monuments; those are shown in the 5th attachment. As expected, none of the monuments are well positioned, all show large errors. Well then. So now we have both an error in the longitudinal measurement (but within the error bar) and test stand monuments not where we thought they were. How could this have affected the 2013 BS XY alignment? To figure this out, I used PolyWorks to recreate our 2013 alignment setup, now with our mispositioned monuments and with our longitudinal position error. Since we had to rotate the cartridge to place it on the test stand, I created a new coordinate system that's rotated 90° CW, so the monuments are in the same coordinates as the BS would be once installed in-chamber (I was getting cross-eyed constantly flipping between the IFO and test stand coordinate systems, this made things much easier).

First I wanted to consider how these issues could have affected our 2013 XY position alignment, so I recreated the setup looking at the AR side of the BS. The 6th attachment shows this. There's a lot of info in this picture, so match the below numbered list with the red numbers in the picture. Also, "Theo" is my shorthand for theodolite, which is another name for a total station.

These are our targets: The target XY position of the AR surface of the BS and the target theodolite sighting line. I created the target sighting line by making a line from our total station monument, TS2-18, and the target AR position. The listed angles are from the nearest axis, so X Acute Ang is measured from the -X axis and Y Acute Ang is measured from the +Y axis. The listed angles are calculated by PolyWorks based on the nominal positions of TS2-18 and the BS AR surface.
These are our total station setup monuments. The total station was set over monument TS2-18 and sighted TS2-11 to create the 0° horizontal angle reference, which is represented by the "Theo AR 0 Ref Line". The measured column here is the error in our 0 reference based on the misposition of monuments TS2-18 and TS2-11. Y Ang is the angle measured from the positive axis, +Y axis in this case, so while we thought we were setting our 0 reference parallel to the X axis, we were actually setting it 0.0012° CCW of the X axis. 0.0012° ~= 4 arcseconds ~= 20 µrad, so not a huge angular deviation.
Here's where things start getting a little tricky. There's 2 boxes here, "Theo AR Actual Sighting Line" and "BS AR Center w/ Devs". We'll consider the Actual Sighting Line first.
1. So, according to PolyWorks we should have turned an angle of 45.1052° from our 0 Ref Line to sight the target center of the BS AR surface, but this is not the angle we were told to turn. The actual angle we turned was 45.1047°. Again, a very small difference (0.0005° ~= 2 arcseconds ~= 10 µrad). So the "Theo AR Actual Sighting Line" nominal column shows the angle we actually turned back in 2013, and the line length is the target longitudinal length from the total station to the BS AR surface. The Measured column shows what the angle actually is once the 0.0012° CCW deviation of our 0 Reference Line is taken into consideration. I should also note that the Actual Sighting Line originates at TS2-18, with the nominal line originating at the nominal TS2-18 coordinates while the measured line originates at the measured TS2-18 coordinates.
2. The box "BS AR Center w/ Devs" shows the point that we would have been pointing the total station at assuming we had no deviation in longitudinal distance (which is what we measured in 2013 with the total station's distance measurement function); in other words, if we had no positioning deviations with the BS at all, this is where the center of the BS AR surface would have ended up. The nominal column only considers the small 0.005° angular deviation between the angle we turned and the angle PolyWorks calculated we should have turned. As seen, this small angle does not cause much of a shift in AR surface position, a handful of µm in both X and Y. The measured column, however, is much more interesting. This column considers both the 0.0012° error in our 0 Reference Line and the mispositioning of monument TS2-18. As can be seen, the misposition of TS2-18 puts the AR center well off of its target, but still within our positioning specification.
Number 3 assumed no longitudinal position deviation in the BS AR surface, and while that's what we measured in 2013 our 2026 measurements showed the longitudinal position of the AR surface was 1.8 mm longer than it should have been. As I've said previously, this is within the error bar of the total station's distance measurement function that we used in 2013, so we would not have seen this deviation at the time. But now that we have seen it, how did this change the 2013 alignment? Queue the next set of boxes, "Theo AR Act Sighting Line + Length" and "BS AR Center w/ Devs + Length". These boxes provide the same information as given in Number 3, but now I've included the +1.8 mm longitudinal deviation that we have now measured (thanks to the FARO). The nominal column here is the same as Number 3, so I'll only talk about the measured column.
1. Now the measured column is including 3 different deviations: The 0.0012° deviation in the 0 Reference Line, the misposition of monument TS2-18, and the +1.8 mm longitudinal position deviation measured with the FARO. As can be seen, this pushes the AR center further away in X but closer in Y, but still within our position specification for the BS.
To see how this compares to our 2026 measurement I added that in as well. I placed the point that we ended setting the total station over into this test stand coordinate, then created a line at the angle we turned for the measurement. Interestingly, this was yet another different angle than the one we used in 2013. The nominal column for the 2026 sighting line lists the angle calculated by PolyWorks, 45.1058°, which was slightly different from what we used for our real test stand measurement, 45.1061°, which again differs from the 45.1047° used in 2013. This 0.0003° is approximately 1 arcsecond, or ~5 µrad, so a very small difference. The measured column for the sighting line is slightly different, however. I wanted to place a point where we measured the BS, which means I had to consider both the longitudinal deviation (seen in the length of the line) and the horizontal deviation. To include the horizontal deviation I calculated the angle subtended by the -0.7 mm horizontal deviation and the measured distance to the BS AR surface (which includes the longitudinal deviation). This angle was 0.0085° (arctan 0.7/4713.6). I subtracted this angle from the 45.1061° we turned to sight the target center of the BS, since the horizontal deviation puts the AR side closer to the -X axis, then created a point at the end of the line. The measured column of the box "2026 BS AR Measured Position" is this point. As can be seen, it closely matches the deviation I calculated in the table above, but doesn't quite match the positional deviation seen in Number 4; X position is decently close, within a couple tenths of a mm, but Y deviation is roughly 0.5 mm. While I don't have an explanation for these small differences, this does show that the mispositioning of the test stand monuments makes up a large portion of the difference between our 2013 BS position measurement and our 2026 one.

That's all well and good for X and Y, but what about the Z axis deviation between 2013 and 2026? Again, all I have to fall back on is 2013 equipment setup errors or things drifting over the course of the last 13 years. For equipment setup, we set optic height by setting the total station at a target distance down from the ISI, using a scale attached to a fixed-length rod, that matched the desired Z axis position of the BS. There could have been an issue with the scale/rod setup (such as a mistake in rod length (not likely) or the scale not mounted properly) or an issue with the total station setup (such as not well levelled or sighting the scale along a zenith angle other than 90°). While I'd like to think that 2013 me would not have made such obvious mistakes, 2026 me doesn't have perfect recall of events from over a decade ago so I cannot say for sure.

For pointing I made our HR test stand setup in PolyWorks, this is shown in the 7th attachment. This is much simpler as I'm only looking to see if the monument misposition caused a large yaw error back in 2013. Quick explanation, we set our total station/LAC combo over monument TS2-20 and sighted monument TS2-19 to set our 0° reference line. We then turned 44.9711° so we were sighting parallel to the HR surface normal of the BS; the gap between the 2 lines in the picture was handled by a Lateral Hollow Transfer Periscope, a device that horizontally translates the beam by ~400 mm while keeping the output beam parallel to the input beam by 1 arcsecond (0.0003°). For a 710 µrad CW yaw deviation in the BS to be caused by the monument mispositioning the deviation of the 0 Reference Line would have to be 0.0407° in the CW direction; this would be a measured X Angle of the line "Theodolite HR HA Ref" of 90.0407°. Clearly, this is not the case. In fact, the angle deviation caused by the monument misposition is only 0.0019°, or ~33 µrad, in the CCW direction. At this point, the only explanation I have for the difference in yaw between 2013 and 2026 is an equipment setup error in 2013 or things subtly shifting in the last 13 years. Keep in mind, we're not talking large shifts in the BS to cause this yaw. If we hold one side of the BS fixed in position and then yaw it by 710 µrad, the opposite side only moves by 0.26 mm (0.000710 * 370.0 = 0.263).

Wrapping Up

So, what does this all mean? Well, with the mistake in using the Build/Inspect automatic compensation mode we don't have any better of an idea where the BS was in the IFO XYZ coordinate system than we did before the cartridge was disassembled. The measurement looks good, but as I explained above I do not trust it. The support tube measurement indicates a -X shift from nominal and a CCW yaw, but these aren't good metrics since support tube length wasn't a critical dimension during tube construction (we've measured 4 so far and all 4 have been different by several mm). I wish I had better news to report here, but we didn't notice the mistake until after the cartridge had been removed from the WBSC2 chamber so there was no way to remeasure the in-chamber position.

The test stand measurements show that the BS SUS was on the edge of our positional tolerance for the optic, with a few points just outside of it. The optic itself, the object of primary importance and the only thing we actually measured in 2013, was within our positional tolerances but different from our 2013 measurements. The primary causes of this were found to be errors in the positions of the test stand brass monuments that we used to set our alignment equipment during the intial 2013 alignment, and the large error bar in the total station's distance measurement mode. The pointing was found to be well outside our tolerances, and I currently cannot explain the yaw deviation. Looking back through my old install notes we never had our test stand pitch alignment survive being craned into the chamber (ITMx shifted by over 2 mrad in pitch after being craned into the WBSC3 chamber), so the pitch being off wasn't really surprising. But the yaw was. Our measurements of the test stand monuments, despite the position deviations, did not show a large yaw deviation. The angle we turned the total station to measure the yaw was different between our 2013 alignment and 2026 measurements, but only by ~24 µrad so not enough to account for the 710 µrad CCW yaw we measured in 2026. We couldn't find any obvious cause of this, so all I can offer are guesses (procedure mistake, equipment setup mistake, small drifts over 13 years, etc.).

AOS, SUS, SYS

Images attached to this report

H1 ISC - Using SQZ to check BS alignment

camilla.compton@ligo.org — Thu, 18 Jun 2026 14:39:22 -0700

Author: camilla.compton@ligo.org

Report ID: 90665

Sheila, Keita, Betsy, Elenna, Ibrahim, Oli, Tom, Camilla. Follow on from 90656

Summary: For BS alignment checks, we spent some time with the SQZ beam to check that we are happy with the SRC pointing. We could not find a beam using the BS sliders only. But we could see SQZ beam reflected off both ITMX and ITMY on the IR viewer paper at PR2. Beam splitter is being moved to overlap these SQZ beams.

Details:

Injecting 1.25mW on SRM from SQZ seed (75mW SEED), expect 0.875mW on AS_A, get 0.77mW (fine).

With ITMY aligned, SR2, SRM mis-aligned, we expect 2.5 counts of AS_A and AS_B (1.25mW * 0.3 SRM * 0.5 BS * 0.5 BS * 0.3 SRM), we could get this on AS_A and AS_B after we reverted SR3 to O4 sliders and started with SR2 at O4 sliders but moved significantly to get light on AS_A and AS_B.

Once SRM was aligned, we could see a beam not centered on the camera. We then realized the ITMs were far off (for Oplev centering in 90443) and then started taking ITMY back towards sliders walking with SR2 (ZM6 didn't have enough range) to get a round beam more centered on AS_AIR camera. *Sheila was later unsure we should have moved ITMY like this.

After this we could see SRY fringes, there were +/-10 counts in size.

We then took ITMX to it's oplev positions last time we had DRMI lock (19 March 2025 18:02 UTC). The sliders/L2 WIT osems were still ~30urad off, think this is okay for this gross BS alignment.

Sheila put a large wobble on the BS while we had ITMX only aligned and we watched the AS_AIR camera and AS_A/AS_B. We could not find the beam off the BS at the HAM6 sensors.

Betsy then went into the chamber and could see the SQZ beam reflected off both ITMX and ITMY on the IR viewer paper clipped at the baffle in front of PR2. Sliders helped bring these beams together but was not enough. Beam splitter is being moved to overlap these SQZ beams...

SQZ

H1 SQZ - HAM7 Vent Wednesday 17th June. Red-Green Co-alignment fixed, Happy with QPD centering

camilla.compton@ligo.org — Thu, 18 Jun 2026 14:30:35 -0700

Author: camilla.compton@ligo.org

Report ID: 90658

Ryan S, Camilla

QPD Alignment and reflections checked

We were not happy with the location of the beam on D:L1 (towards +X) so we iterated the alignment of D:M1 and D:M2 to better center this (picos and by hand). Then touched D:BS1 and B:M3 to center on QPDs (SEED power reduced 1.4mW to check centering). We then increased power (75mW SEED) and checked the refected beams off the QPDs got to the beam dumps.

ZM4,ZM5 for SQZT7 irises

As we moved A:M3 and ZM3 pointing after the OPO SUS was unlocked, we touched ZM4 and ZM5 alignment to bring the beam back centered to SQZT7 irises, sliders attached.

Fixed Red-Green Co-alignment

We inially though either H:M1 and H:M2 might have got bumped but couldn't recover alignment with just one mirror. We then realized that Begum and I moved the red alignment with A:M1 and A:M2 in 90528 so we'd expect the co-alignment to be different. We then moved H:M1 for centering on the ZM1 iris and H:M2 for the ZM3 iris until we were happy with co-alignment, all moves were with picos only. Once finished, we couldn't not see the retro-refected FC beam so expect it's well retroreflected. Photo and movie attached.

We could see a green beam on SQZT7 but it was missing the LPM, can verify this FC REFL and check centering later.

Addtioanlly, now the OPO SUS is unlocked, the SK path is back to where it was prep vet on SQZT7 (clipping but on the LPM), photos attached.

Images attached to this report

Non-image files attached to this report

redgreencoalign_mov.mov

LHO FMCS - Corner Station chiller sequence rotated

eric.otterman@ligo.org — Thu, 18 Jun 2026 14:12:32 -0700

Author: eric.otterman@ligo.org

Report ID: 90668

The lead chiller at the corner station was changed from chiller 1 to 2. This is due to a condensing pressure fault that occurred overnight on chiller 1. The sequence is now chiller 2 - lead, chiller 1 - lag, chiller 3 - standby. Troubleshooting of chiller 1 will be done next week.

H1 SEI - ISI HAM3 Wide Wall Balance Masses vs. SPI

jeffrey.kissel@ligo.org — Thu, 18 Jun 2026 13:19:54 -0700

Author: jeffrey.kissel@ligo.org

Report ID: 90667

J. Kissel, J. Warner During SPI install we removed the following side-wall balance mass from the W9 side wall (see first bullet of LHO:90558): Plate Mass [lbs.] Mass [kg] QTY Total Mass [kg] D071200 Type 04 7.9 3.583 3 10.750 D071200 Type 01 1.1 0.499 1 0.499 D071200 Type 00 0.6 0.272 1 0.272 D071201 0.1 0.045 3 0.136 Total Mass 11.657 First attachment is a diagram to convey which side wall I'm talking about. This is inaccurate with the latest version of the ballast / balance mass inventory, D1000907-v7, which states that this side wall has only 1x Type 04 (3.583 [kg]) and a 1x Type 03 (2.041 [kg]), for a total of 5.625 [kg]; much less. Remember, from LHO:90504 that the total SPI mass is 12.599 [kg]. This *excludes* the mass of the lower ISI Shroud baffle (D2400106-v4) and the three upper HAM Table Baffles (D2600007) with all their bracketry and bolts, currently only represented only in e-drawings posted to D2400103-v6. After talking with Jim, he wants more mass in this -X / +Y corner of the table, because that's where all the new stuff is. So he wants this corner "over" or "heavy" (because the new stuff must be in a fixed position) so that he can adjust the *opposite* corner of ballast mass (which has more open table and side wall access and thus is adjustable). As such, he says "put all the at 11.657 [kg] back on the corner. So we will! Second attachment is a picture of the wall mass arrangement prior to us removing it taken on 2026-06-09. SEI, SPI, SYS

Images attached to this report

H1 SUS - OPLEV charge measurements, ETMX, ETMY

ryan.crouch@ligo.org — Thu, 18 Jun 2026 12:40:06 -0700

Author: ryan.crouch@ligo.org

Report ID: 90666

I ran the OPLEV charge measurements this morning for the both of the ETMs.

For ETMX the charge is still trending towards zero on all DOF/quadrants, LR and UR have the highest charge around ~60-70 V but they're trending down.

For ETMY the charge seems stable at or just above +50 V on most DOF/quadrants. The error bars are pretty big for EY, but the measurements all had great coherences. In each individual measurement none of the errors look very large except for LR which is broken/not used.

Images attached to this report

LHO General - Ops Day Shift Start

thomas.shaffer@ligo.org — Thu, 18 Jun 2026 07:35:34 -0700

Author: thomas.shaffer@ligo.org

Report ID: 90664

TITLE: 06/18 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: 9mph Gusts, 4mph 3min avg
Primary useism: 0.02 μm/s
Secondary useism: 0.14 μm/s
QUICK SUMMARY: The LVEA is still in laser hazard, but the light pipe is currently closed. SPI, BBS, SQZ chamber work continues today.

H1 CDS - Extended edc_green_ioc to include missing PWREX

david.barker@ligo.org — Thu, 18 Jun 2026 07:07:33 -0700

Author: david.barker@ligo.org

Report ID: 90663

While Patrick is upgrading the EX Beckhoff power monitor IOC I have added these channels to the temporary edc_green_ioc.py to "green up" the EDC by supplying the missing 82 channels. IOC was restarted at 07:03

LHO VE - CP1 Cooldown Started

gerardo.moreno@ligo.org — Thu, 18 Jun 2026 01:26:13 -0700

Author: gerardo.moreno@ligo.org

Report ID: 90662

(Jordan, Travis, Jake, Owen, Gerardo)

After taking some RGA scans of CP1, and pushing nitrogen gas through the cryotrap (we injected nitrogen gas at the top sensor line for about 10 minutes), then we started the cooldown, or did we? First, we opened the "bypass" valve (fully open) to measure the number of turns to guesstimate a less than 10% open valve, per procedure E960127. Then we opened the bottom draw valve to release LN2 out of the dewar. We opened both valves around 2:00 pm, bottom draw fully open and bypass valve only 10%, but by 7:40 pm local time we terminated the cooldown, we didn't want to risk for something to go array overnight.

We did not see a sign that the cryotrap was getting nitrogen, nothing on the exhaust (the exhaust pressure remained the same), nothing on the cryotrap level (remained at zero), pressure internal to the cryotrap remain level, and the consumption remained level at the dewar for CP1. We are going to look more into this Thursday.