TITLE: 04/29 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: 4mph Gusts, 2mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.14 μm/s 
QUICK SUMMARY: Work continues today with the old BS on the test stand and in the vented corner chambers.

I updated and restarted the experimental framewriter on h1daqfw2 today around 2:20pm localtime today.  This was to verify some new code still produced identical frames.

WP13213 Jeff, Tom, Oli, Dave:

h1susbs (the original BSFM model) was changed slightly to no longer drive the 2nd LIGO-DAC chans 08-11. This frees these up for use by the BBSS model. At the same time 4 IPC senders and 11 IPC receivers were removed.

Instead of replacing h1suslo12 with a brand new h1susbbss model, with all the associated RGC/DAQ/puppet changes, we chose to keep the h1suslo12 model essentially in name only, but change its function to drive the BBSS and test QOSEMS.

To do this, Oli changed the h1susbbss.mdl file to:

 - use h1suslo12's dcuid=188

 - remove all IPC senders

 - reduce the number of DAC channels, only using those freed up by the h1susbs changes

This approach means the H1.ipc and testpoint.par files are unchanged. The H1SUSLO12.txt filterfile and safe.snap files are substantially changed, but these had not been commissioned. The H1SUSLO12.ini file was also essentially rewritten for BBSS with the exception of some FEC channels.

There were no issues with rebuilding and installing the new h1susbs and h1suslo12 models. The old versions were stopped before the new ones were started because we are swapping DAC drives between these models.

DAQ Restart

The DAQ was restarted for the model changes. There were no issues found.

CDS Overview

The h1suslo12 entry on the CDS Overview has a new color/label to denote its current usage as the BBSS model. Also note the removal of some IPC senders from h1susbs means we have continuous IPC receive errors on the h1susmc2 and h1seiproc models.

TITLE: 04/28 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:

Test T634314 @ 16:00:30 UTC

Firepump1 is on 16:30:23
FirePump2 on 16:31:20 UTC
Eric confirms that Firepumps are done being used at 16:35 UTC

Vacuum Alarm for PT120B pressure torr started alarming @ 16:42 UTC, likely due to Fil pulling cables.

Dust monitors for LVEA 10 (Which I beleive is the dust mon in the BSC2 area.)
 

Test Frame Writer2 was restarted without incident. 

HEPI Pump pressure diag main. Jim says he'd like this to become a Diag Main flag that gets raised when the following channels are more that 5% off from each other.:  
H1:HPI-PUMP_L0_PS1_PRESS1
H1:HPI-PUMP_L0_PS2_PRESS1
H1:HPI-PUMP_L0_PS3_PRESS1
H1:HPI-PUMP_L0_PS4_PRESS1

MC2 and PR2 were taken to safe while betsy and Travis work in HAM3.

DC0 & FW restarts for new SPI front end models  at 22:13 UTC.

LOG:

The D3 feedthru on HAM3 was swapped from the 3-port version with 3x Dual DB25 feedthrus to the single piece 12x DB25 connector feedthru.  We re-attached the in-vac cables that were originally in that port and Betsy re-attached the in-air cables so that the SUSes can be controlled overnight. 

Summary:

The problem of "Sense" pin of OMCA QPD1 short-circuited to the BHDS structure (alog 90029 from yesterday) was tracked down to the free "sense" wire inside the QPD enclosure touching the aluminum part inside the enclosure. We solved the problem by trimming the wire short.

Merely opening the QPD enclosure broke the short circuit temporarily:

We lifted the OMCA QPD1 from the BHDS while QPD2 is still attached to the BHDS and confirmed that the sense pin for the QPD1 is conductive to the QPD1 enclosure but not to the BHDS. As soon as we opened the back of the QPD1 enclosure, the short-circuit to the enclosure was broken. 

It seemed that the free part of the sense wire was a bit too long and bowed in the enclosure, allowing the tip of that wire to touch the inside wall of the enclosure itself (see Elenna's first image in her comments).

Cutting the sense wire short broke the short circuit permanently:

I cut the wire short such that it cannot touch the enclosure (Elenna's second picture), reassembled the enclosure and confirmed that there's no short circuit between the sense pin and anything else. 

Repeating the tests:

We put the QPD1 back on the BHDS and connected the cable to the transimpedance amplifier. On the oscilloscope, it was immediately apparent that the terrible 60Hz noise (which was 6.5V p-p) was gone (Elenna's 3rd picture).

We repeated the flashlight test, all segments responded with O(1)mV negative voltage (i.e. positive output minus negative output from the TIA amplifier was negative few mV maximum) while the dark offset was O(0.1mV).

We also measured the dark noise. It seems that all measurements for both QPD1 and QPD2 were limited by the noise of the TIA. Low frequency noise especially 60Hz and its harmonics varied from channel to channel, but in all cases it seemed that there's very little difference between the noise measured with QPD connected VS the noise without QPD. As such, I'll just show here a few examples. First attachment is the QPD1 segment 1 noise with the QPD attached, the second is the same thing but without QPD connected to the front panel of the TIA. They look identical. The third one is the QPD1 segment 4 (with QPD attached, not much different without QPD). The fourth one is the QPD2 segment 3 (with QPD attached, not much different without QPD).

There's no reason to suspect that QPD1 for OMCA is broken (nor QPD2).

We pulled, tested, and reinstalled the two 8 channel satellite amplifiers in SUS-R2.

S1106058, S1200173.

Last week I tripped the HEPI pump controller valving out the BSC2 actuators, it took me until today to try to recover it. In the process of investigating this I found that one of the 4 corner station HEPI pump carts has been more or less off since a power outage in December. The remaining pump stations have been running at about 95% drive to cover for the lost cart. I am working on some revisions to the famis and asking to Tony to add a verbal notification if there is a mismatch in the manifold pressures for the 4 corner pump stations.

Nice to know that we have overhead to lose one pump station and still supply the corner HEPI with pressure. Drive is much lower now that all 4 are running again.

Attached image shows how long we have been running with only 3 pumps. Crosshair in the upper left plot shows approximate time of the power outage. Bottom right shows we have been running at ~1900 cts drive out of 2048 total available since then. We are back around 1100 cts drive now.

Mitchell, Rahul

This morning we entered HAM3 chamber and attached the baffles (for stray light control) to both PR2 (HSTS) and MC2 (HSTS) suspensions. The baffle assembly design is shown D1700257_V5. These baffles were attached (directly mounted on the HSTS structure) on both the sides of the optic, i.e  HR and AR side.

Before attaching the baffles I inspected both the optics and they looked nice and clean, hence didn't needed any First Contact cleaning. 

I am attaching pictures below for reference.

We found that both PR2 and MC2 had two missing 1/4-20 threads on the HR side for attaching the mounting rail (D1700249_v1) of the baffle (Mitchell will attach a picture showing the same). Typically, these rail need four holes on the structure for securing them. However, we used the lower two threaded holes for attaching these mounting rail and they were rigidly secured. On the DCC I found that both PR2 and MC2 have D020023_V3 of the HSTS_Structural Weldment Assembly, latest D020023_V7 has more holes on the frame.

We also noted that one of the Siskiyou mount is very close to the MC2 baffle (AR side) as shown in the picture here. However, I can confirm that they are not touching and there is a decent amount of clearance between them. 

I still need to perform health checks on both the suspensions to rule out any rubbing and will post the results as a comment over here.

Note - counts on dust monitor were in single digit before and after entering/exiting the chamber (Thanks to Ryan C for arranging this). 

J. Kissel, J. Freed

It's not the "right" place to find this information, but I was helping Josh get started with git, and I found my 2022 LHO:63463. We needed that step of generating an SSH key and posting it to his git.ligo.org profile. Of course, in 4 years, a minor detail has changed -- the location of where you put it on the web.

So, here's the 2026 version of the instructions on how to generate an SSH (SHA256) key and get ligo.org to recognize it enough to give you permissions to clone a project:

##ALL THE SAME
     jeffrey.kissel@opslogin0:/ligo/gitcommon/Calibration/ifo$ ssh-keygen 
     Generating public/private rsa key pair.
     Enter file in which to save the key (/ligo/home/jeffrey.kissel/.ssh/id_rsa): 
     /ligo/home/jeffrey.kissel/.ssh/id_rsa already exists.
     Overwrite (y/n)? y
     Enter passphrase (empty for no passphrase): 
     Enter same passphrase again: 
     Your identification has been saved in /ligo/home/jeffrey.kissel/.ssh/id_rsa.
     Your public key has been saved in /ligo/home/jeffrey.kissel/.ssh/id_rsa.pub.
     The key fingerprint is:
     SHA256:XQnWdPoBVmHwdsX3i+qpeTvANGQHFiI7zTXFN1oF7ew jeffrey.kissel@opslogin0
     The key's randomart image is:
     +---[RSA 2048]----+
     |     . . *B+=+O+.|
     |      = ++.=.@ .+|
     |     o oo . B B +|
     |      .  + o o =.|
     |        S o   + .|
     |         o   . E |
     |          . .    |
     |          .+.    |
     |         o++o    |
     +----[SHA256]-----+
     jeffrey.kissel@opslogin0:/ligo/gitcommon/Calibration/ifo$ cat /ligo/home/jeffrey.kissel/.ssh/id_rsa.pub 
     ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCebNagyBGRjYsoP4RT8KZ74HLONo6B4VOwBNUQpOPrNnMvQTD3NfTQJHWTgkcAFiCB2yLeioqJQmrigTd9BjnKx/1Eo4z1wvhC/hvCvD07IcvLgogP1lujyDyx7qYHBw46W1pFXXt1wqkFYFiDxcsNRgqhFqFBvdyVJdfPZs+GHqK8Df6AfKKZTWqrYgzpqYbvzl9q21E3vEUyTQamoftBimCZVSj1cz7+5W7giWBcBNmcuHzrV2/Af7pfzj8zoveXv/9qISyLKp0F4zlB52/lih9TzxTg36l8MCzIb2592xVsRaYtuxb8SA4Sst8bUqVvUFclj/rCD1ytEDfMvKyp jeffrey.kissel@opslogin0

###HERE'S WHERE IT'S DIFFERENT

Then I 
- went to https://git.ligo.org/-/user_settings/ssh_keys/ (####INSTEAD OF https://git.ligo.org/-/profile/keys)
- copied the above public id_rsa.pub hash into the "Key" field, 
- then let it auto-title the key,
- change the with expiration date something in the year 2080, and 
- hit the blue "add key" button.


Now, you can, say go to the https://git.ligo.org/spi/simulation/ page, and hit the blue "Code" button (####it's no longer called "Clone"), hit the two squares icon for copy in the "Clone with SSH" address, then in a (new or refreshed) terminal type

    $ git clone git@git.ligo.org:spi/simulation.git

and you're in business. 
From there, the CONTRIBUTING guide to pydarm is a place that I found the most helpful in how to develop / interact with a git project.

Tue Apr 28 10:09:03 2026 INFO: Fill completed in 9min 0secs

Today, with the BS SUS set to SAFE and the SEI chassis turned off at the rack, Tony, Ibrahim and I started unplugging and logging all of the cables in the chamber at the feedthrus.  I have a master log going which will be posted as an As-Built to the D1003079 BSC2 Flange Feedthru Layout Drawing for future re-plug-in activities.  Pictures of 2 feedthrus prior to unplugging are attached for samples of what I'm talking about.

As well, we dropped the ITMX Elliptical Baffle and Down Tube Sub assemblies from Stage 2 and have a good start on the ITMY one but didn't finish since it has mismatched hardware and we need a different tool.  (In the event we need to put them back up, we left them off to the sides of the chamber to deal with later - the ITMX one is the one closest into the ITMX chamber.)

Also also, we locked the BS SUS, tightened all of the nuts, removed all of the Vibration Absorber Cubes, and put the sock on the full SUS.

Tomorrow we need to:

Add the BS Face cover
Remove a Stay or 4
Finish stowing all of the dangling cables
Finish removing the ITMY Elliptical Baffle
Get on with the Support Tube and SEI work

Jennie W, Jeff Kissel,

Summary: Can we see a difference in jitter with JAC in the IMC ASC sensors? Short answer, yes.

The IMC has less angular motion with JAC installed at some frequencies - jitter is being suppressed by the JAC so less input beam motion relative to the cavity axis. The QPD readouts are noisier with JAC but there is one new suspension between JAC and the IMC so maybe the beam pointing to MC1 is noisier? MC2 TRANS QPD looks pretty similar with and without JAC, but this makes sense as cavity axis is still well aligned to this QPD. I need some other figure of merit to look at jitter as it only limits the IFO above 20 Hz, see alog #86555 by Sheila.

Since there was no time for a full IFO lock betwen the HAM1 vent and the current vent of the corner volume, we cannot directly check whether the jitter coupling to DARM is better with the JAC cavity.

We have lots of data of the JAC and IMC locked after the installation of JAC, however.

So I compared two times when we had roughly 2W input from the PSL to HAM1. In both cases H1 and the corner were at vacuum to rule out confounding effects from purge air and other sound noise seen when HAM1 was at air.

In both these cases the IMC was locked.

The two times I used were:

2025/11/17 15:38:54 UTC no JAC, during O4c

2026/03/20 00:26:01 UTC JAC installed, HAM1 at vacuum

Here is the ASD measurements for five sensors in the pitch degree of freedom:

IMC REFL WFS A  Roughly the same above 10Hz with and without JAC. Better with JAC between 0.3 and 7Hz.

IMC REFL WFS B Roughly the same above 10Hz with and without JAC. Better with JAC below 7Hz.

IMC REFL QPD A has lower noise now below 5Hz than before JAC installation and much higher noise at frequencies above 10Hz.

IMC REFL QPD B has lower noise now below 3Hz than before JAC installation and much higher noise at frequencies above 10Hz.

MC2 TRANS QPD roughly the same with and without JAC.

Jitter noise is more of a problem in the 20-800 Hz region, which these plots don't tell us much about.

I also need the check YAW