H1 returned to observing at 21:53 UTC after several hours of downtime due to earthquakes and high winds. The wind has calmed down enough that I was able to relock after an initial alignment.

I accepted the SDF diffs Sheila predicted in alog83483 before going to observing, screenshot attached.

Bi-Weekly TCS Chiller Water Level Top-Off Famis 27811

CO2X

• Before: 29.5
• After: 30.2
• + 250 ml

CO2Y

• Before: 9.9
• After: 10.5
• +175 ml

There was no water in the leak cup.

Fri Mar 21 10:05:37 2025 INFO: Fill completed in 5min 34secs

HEPI Pump Trends Monthly. Last Checked in alog 82928. Closes FAMIS 37203.

Trends look as expected and are comprable in noise to last month.

Since I changed the ramp time to 2 seconds for the second time, there hasn't been a change in the rate of these locklosses, there have been 8 per nln lockloss since March 18th at 21 UTC.  I've now changed the ramp time back just to avoid an unnecessary change to ALS.

Oli used data from the lockloss tool to make this useful plot showing how many locklosses we've had from the LOCKING_ALS state (state 15 for ISC_LOCK), blue shows the total number of state 15 locklosses for that day and orange shows those that were tagged as high wind or EQ.  This shows the problem starting on the 22nd or 23rd UTC time, which might line up in time with this change to the ALS demod phase and locking gain: https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=82388

Because of the large EQ right now, we can't lock the Y arm to measure the TF.  I've reverted the changes, and accepted the changes in SDF safe.snap.  They will need to be accepted in observe.  It would also be a good idea to measure the OLG when we can.

FAMIS 26376, last checked in alog83399

Laser Status:
    NPRO output power is 1.834W
    AMP1 output power is 70.15W
    AMP2 output power is 140.0W
    NPRO watchdog is GREEN
    AMP1 watchdog is GREEN
    AMP2 watchdog is GREEN
    PDWD watchdog is GREEN

PMC:
    It has been locked 44 days, 19 hr 39 minutes
    Reflected power = 22.58W
    Transmitted power = 106.0W
    PowerSum = 128.5W

FSS:
    It has been locked for 0 days 0 hr and 12 min
    TPD[V] = 0.7967V

ISS:
    The diffracted power is around 3.9%
    Last saturation event was 0 days 0 hours and 55 minutes ago

Possible Issues: None reported

Lockloss @ 15:00 UTC - link to lockloss tool

S-waves from two M6.2 earthquakes, one from Panama and another from the Aleutians, AK hit at pretty much the same time, sending H1 into EQ mode and losing lock. Since the R-waves are still 15 minutes out from the Panama quake and there have already been some aftershocks, I'm leaving H1 in DOWN until those pass by.

TITLE: 03/21 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 141Mpc
OUTGOING OPERATOR: Ibrahim
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 23mph Gusts, 18mph 3min avg
    Primary useism: 0.04 μm/s
    Secondary useism: 0.34 μm/s
QUICK SUMMARY: H1 has been locked and observing for almost an hour; two locklosses overnight. Ibrahim notes he was called this morning and I've cleared the H1_MANAGER alert.

• Wind up and down overnight, currently gusts up to around 30mph
• All other systems nominal, no alarms

IFO is in NLN and OBSERVING as of 13:43 UTC <5 minutes after getting the OWL call. I did not touch anything.

Was called at 6:37AM. Logged on to check what the problem was but it seemed that we just hit the 2 hour post-lock OWL call threshold, seemingly due to high winds preventing lock/causing lock acquisition lock losses.

By 6:41AM, we were locked and OBSERVING by 6:43 AM.

I am having issues clearing the OWL due to a NoMachine Malfunction. Will leave it to DAY OPS in 30 mins.

(Gerardo, Janos, Rogers Machinery Techs (Samuel Ragsdale and Brandon Pimentel))

Late entry.

On Tuesday, we had a couple of service technicians from Rogers Machinery complete the annual maintenance for the Kobelco compressor, no hiccups were encountered during the maintenance job.
A couple of notes regarding the service:

1. water hoses and tubing will need to be replaced probably by the next service.
2. the aftercooler o-ring sealing surface is showing wear, and it will need inspection during the next service.  

The compressor will be ready to use once we test and get an acceptable dew point.

(Jordan, Gerardo, Janos)

Late entry.

Last Tuesday 3 ion pumps were incorporated to the filter cavity tube.  The ion pumps were installed some time ago, and they remained valved out until last Tuesday.
The ion pumps are located on the filter cavity tube crosses B4, B5 (installed here) and C1 (installed here).
New MEDM screens were created for the signal for each pump (see first attachment), each respective signal is obtained from each of the ion pump controllers, for these ion pump we are using the LPC GAMMA type controllers.  For the pressure effect see second attachment.

To incorporate the ion pumps, FC-B-4 and FC-B-5 to the rest of the filter cavity 3 valves were closed, FCV-3, FCV-4 and FCV-5.  Then to incorporate ion pump FC-C-1, valve FCV-6 was closed.  After the performance of the ion pumps was confirmed all the gate valves were opened.

TITLE: 03/21 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 149Mpc
INCOMING OPERATOR: Ibrahim
SHIFT SUMMARY: Relocking was automated and quick when the wind died down. We've been locked for ~ 4 hours.
LOG:                                                                                                              

01:11 UTC Observing

TITLE: 03/20 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Wind
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 32mph Gusts, 19mph 3min avg
    Primary useism: 0.05 μm/s
    Secondary useism: 0.30 μm/s
INCOMING OPERATOR: Ryan C
SHIFT SUMMARY:
Today's Comissioning plans were marred by locklossed caused by sustained 30+ MPH wind speeds with 40-50 MPH gusts.
Initial_alignment had been done and a number of attempts to lock were tried during a handfull of slight breaks in the wind.
But those were all blown away with the tumbleweeds.
When the Wind was sustained about 35 MPH I was holding the IFO in IDLE.
Observatory mode was set to Windy.

LOG:                                                                                                                 

TITLE: 03/20 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Wind
OUTGOING OPERATOR: Tony
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 36mph Gusts, 22mph 3min avg
    Primary useism: 0.06 μm/s
    Secondary useism: 0.38 μm/s
QUICK SUMMARY:

• We've been down for the WIND for the majority of the day
  • The forecast doesn't look good, there might be a small lull around 8 to 11pm from windy.com

J. Kissel

Oli and I are beginning the process for designing damping loops for the A+ O5 BBSS. We're running through the same process that I've been running through for over a decade designing suspension damping loops, in which I build up a noise budget for the optic displacement in all DOFs using input noises for seismic noise, DAC noise, and OSEM sensor noise filtered through said damping loops, all propagated thru the matlab dynamical model of the suspension.
 
The first step along that journey is revisiting all the input noise sources, and making sure we have good model for those. 
OSEM noise and DAC noise models have recently been validated and updated when I revisited the HLTS damping loop design (see LHO:65687).
However, I haven't worked on damping loops for suspensions suspended from a BSC-ISI since 2013, see G1300537 for the QUAD, G1300561 for the BSFM, and G1300621 for the TMTS.
In those, I used the 2015 update to the 2005 requirement curve from T1500122 as the input motion.
Now, after a decade worth of commissioning and improvements, I figure it's time to show that work here and use it in modeling future SUS damping loops where the SUS is mounted from a BSC-ISI.

One of the biggest things we've learned over the decades is that the seismic noise input to the suspension at its "Suspension Point" motion for a given suspension can be the (quadrature) sum of many of the ISI's cartesian degrees of freedom, and depends on where and in what orientation it is on the optical table (see T1100617). As such, we installed front-end infrastructure to calculate the calibrate the lowest stage sensors -- the GS13 inertial sensors -- into both the Cartesian and Euler basis (see E1600028). In this aLOG, I do as I did for the HAM-ISI LHO:65639, I show the Cartesian contributions to each of the Beam Splitter's SUS point motion, by multiplying the Cartesian channels by the coefficients in the CART2EUL matrix for the beam splitter.

The time I used for this performance of the H1 ISI BS was 0.01 Hz binwidth (128 sec FFT), 10 average, 50% overlap data set starting at 2025-03-19 14:00 UTC.
    - This was a late night local set, with no wind and 0.1 [um_BLRMS] level microseism (between 0.1-0.3 Hz)
    - GND to ST1 Sensor correction is ON, including the DIFF and COMM inputs.
        - Here at H1, the corner station does NOT have beam rotation sensors to improve the GND T240 sensor correction signal. But, both end stations have a BRS.
        - The wind was low at this measurement time, but it's worth saying that each end-stations wind fences are in dis-repair at the moment, too be fixed soon.
    - ST1 Z drive to ST1 RZ T240 decoupling is ON with a "pele_rz" filter
    - Off diagonal ST1 dispalign matrices are in play, 
         X to RX & RY = -1e-4 & 1e-4, 
         Y to RX = -7e-4, 
         Z to RX & RY = 3.5e-3 & 2.5e-3 
    - ST1 Blend Filters:
        - X & Y = nol4cQuite_250
        - Z = 45mHz_cps
        - RX & RY = Quite_250_cps
        - RZ = nol4cQuite_250.
    - As far as I can tell, there's NO ST1 to ST2 sensor correction on the ST2 CPS, nor is there and ST1 to ST2 FF to the ST2 actuators.
    - ST2 Blend Filters:
        - X & Y = 250mhz
        - Z = 250mhz
        - RX & RY = tilt_800b
        - RZ = 250mhz

These will be used to make updates to 
    /ligo/svncommon/SusSVN/sus/trunk/Common/MatlabTools/
        seisBSC.m or 
        seisBSC2.m
which are toy models of the BSC-ISI performance, used so you don't have to carry around some giant .mat file of performance and you can per-interpolate on to an arbitrary frequency vector, much like I did for seisHAM.m in CSWG:11236.

I've committed the .xmls and .pngs in the following SeiSVN directory:
/ligo/svncommon/SeiSVN/seismic/BSC-ISI/H1/BS/Data/Spectra/Isolated/ASD_20250319/

At the EY station the compressor is being replaced - after the one at EX is done. In this aLog, in the comments, the progress of this operation is tracked continuously, until the 1st startup by the supplier, Rogers Machinery.
Another important consideration here, is that the purge line at EY needs to be replaced (based on an FTIR test - see DCC LIGO-E2300222-v2. As it can be seen, the level of contamination reaches even the 10 ug/cm2 value). This operation will be done after the April-May vent, so the EY station will be ready to be vented after O4.

02-25 (maintenance Tuesday): the old compressor was pulled out (it is temporarily stored in the EY receiving area). The beginning of the purge and TMDS lines with the associated brackets and unistruts were taken off. The new compressor unit and dryer skid were anchored in the mechanical room. Here it is important to mention that the orientation of the inlet was brought closer to the purge line inlet into the VEA, so the overall length of the associated circulation lines will be much shorter.
Next is the electrical and pneumatic installation, which will be completed in the next 1-2 weeks.

Jennie W, Sheila

Summary: We altered the offsets on the H1:ASC_OMC_{A,B}_{PIT,YAW} QPDs which are used to align the beam into the OMC. This was aiming to give us a improvement in optical gain. After doing this we aimed to measure the anti-symmetric port light changing as we chnage the darm offset. We are trying to use both these measurements to narrow down where we have optical loss in that could be limiting our observed squeezing. Performed both measurments successfully but the different alignment of the OMC made the squeezing less good so Camilla (alog #83009) needed to do some tuning.

Last time (alog #82938) I did this I used the wrong values as our analysis used the output channels to the loops instead of the input channels which come before the offsets are put in. The new analysis of our measurement of the optical gain as seen by the 410Hz PCAL line, changing with QPD offset, shows that we want the loop inputs to change to:

H1:ASC_OMC_A_PIT_INMON to 0.3 -> so we should change H1:ASC_OMC_A_PIT_OFFSET to -0.3

H1:ASC_OMC_A_YAW_INMON to -0.15 -> so we should change H1:ASC_OMC_A_YAW_OFFSET to 0.15

H1:ASC_OMC_B_PIT_INMON to 0.1 -> so we should change H1:ASC_OMC_B_PIT_OFFSET to -0.1

H1:ASC_OMC_B_YAW_INMON to 0.025 - so we should change H1:ASC_OMC_B_YAW_OFFSET to -0.025

We stepped these up in steps of around 0.01 to 0.02 while monitoring the saturations on OMC and OM3 suspensions and the optical gain, both to make sure we were going in the correct direction and that we were not near to saturation of the suspensions as hapenened last time I tried to do this.

Attached is the code and the ndscope showing the steps on each offset, (top row left plot, top row center right plot, second row left plot, second row center right plot). The top stage osems for OM3 suspension are shown in the third row left plot, the top stage osems for OMC suspension are in the third row center left plot, and the optical gain is shown in the third row right plot.

The optical gain improved from by 0.0113731 from a starting value of 1.00595, so that is an improvement of 1.13 % in optical gain.

Around 19:04:28 UTC I started the DARM offset step to see if the change in optical gain matches that we would see if we measured the throughput of HAM 6. Unfortuntely I forgot to turn off the OMC ASC which we know affects this measurement of the loss. We stood down from changing the OMC and Camilla did some squeezer measurements, then I made the same mistake again the next time I tried to run it (d'oh). Both times I control-C'd the auto_darm_offset.py form the command line which means the starting PCAL line values, and DARM offset had to be reset manually before I ran the script successfully after turning the OMC ASC gain to 0 to turn it off.

The darm offset measurement started at 19:20:31 UTC. The code to run it is /ligo/gitcommon/darm_offset_step/auto_darm_offset_step.py

The results are saved in /ligo/gitcommon/darm_offset_step/data and /ligo/gitcommon/darm_offset_step/figures/plot_darm_optical_gain_vs_dcpd_sum.

From the final plot in the attached pdf, the transmission of the fundamental mode light between ASC_AS_C (anti-symmetric port) DCPD is (1/1.139)*100 = 87.8 %. We can compare this to the previous measurement from last week with the old QPD offsets to see if the optical loss change matches what we would expect from such a change in optical gain.