We lost lock during commissioning for unknown reasons at 1800UTC. Relocking required an initial alignment, and DRMI took 12 minutes to lock, but it got there and we are now Observing at 1944UTC.
Today I began calibrating the camera servo signals into spot positions. I ran the A2L script at the nominal camera spot positions. Then, I changed the camera offset and waited for the camera servo to converge. Then I remeasured the A2L gain. Using the a2l_lookup function in /opt/rtcds/userapps/release/isc/common/scripts/decoup/BeamPosition the A2L gain can be converted into a spot position in mm. This is a slow process so it will take time to get the conversions for all.
| Camera offset | A2L gain | Conversion | |
| ETMY Pitch | start: -230, end: -231 | start: 5.62, end: 5.92 |
(-23.2 mm - -21.8 mm)/-1ct = 1.4 mm/ct |
| ITMX Pitch | start: -230, end: -231 | start: -0.45, end: -0.56 |
(6.46 mm - 5.96 mm)/-1ct = -0.5 mm/ct |
Thu Oct 02 10:07:28 2025 INFO: Fill completed in 7min 24secs
Matt, Camilla
After TJ and Dave fixed the HWS Live GUI 87252, Matt and I checked on it and re-centered the origin crosses which are meant to mark the center of where the IFO beam is heating the ITM, before and after, sdf diff. We moved them both down but we hadn't updated them in a few years so this isn't too surprising.
Also attached is a HWS image of the test masses comparing getting to 60W in to 180s later, plot. As usual, ITMY looks clean and ITMX has it's known point absorbers. There is some edge effects on ITMX that should be ignored.
TITLE: 10/02 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Lock Acquisition
OUTGOING OPERATOR: Ibrahim
CURRENT ENVIRONMENT:
SEI_ENV state: USEISM
Wind: 12mph Gusts, 8mph 3min avg
Primary useism: 0.03 μm/s
Secondary useism: 0.41 μm/s
QUICK SUMMARY: Looks like we lost lock 2 hours ago. An initial alignment was done an hour ago, but DRMI is not catching despite high flashes.
Planned calibration and commissioning today, but we need to get back up first.
TITLE: 10/01 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 151Mpc
INCOMING OPERATOR: Ibrahim
SHIFT SUMMARY:
H1 has been locked over 18hrs with no issues this shift.
I took some more histograms of our locking sequences today.
ALS
DRMI-BiWeekly
DRMI-Monthly
DRMI-Daily Average
Carm
Powerup
& NLN
Checking in on our DARM lockloss status after the second month of having our higher bias. At the end of August I put some comparison plots in to show how the doubling of the bias had significantly decreased the number of locklosses we had, as well as also significantly decreasing the amount of those locklosses that were due to the DARM glitch(86678). I remade those plots again now that we've gone through September.
In my usual lockloss vs DARM lockloss plot, we see that we've actually had no locklosses due to the DARM glitch between September 3rd - September 30th, which is the longest we've gone in all of O4 without that lockloss cause!
The average lock length has gone down a bit compared to August (10.8 vs 13.3 hours), but that's still double the average lock length of February, March, June, and July (table, plot). The number of lockloses is still also much lower than the pre-ESD-doubling months.
TITLE: 10/01 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 152Mpc
OUTGOING OPERATOR: TJ
CURRENT ENVIRONMENT:
SEI_ENV state: USEISM
Wind: 8mph Gusts, 5mph 3min avg
Primary useism: 0.04 μm/s
Secondary useism: 0.59 μm/s
QUICK SUMMARY:
H1's been locked 12.5+hrs, even with microseism a little higher than last night! Cloudy skies, light breezes and an Operator BBQ celebrating O4a & Detections operators were on-shift for.
TITLE: 10/01 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 152Mpc
INCOMING OPERATOR: Corey
SHIFT SUMMARY: Locked for 12 hours. The useism is staying constant, wind is staying low.
LOG:
| Start Time | System | Name | Location | Lazer_Haz | Task | Time End |
|---|---|---|---|---|---|---|
| 22:52 | LASER | LVEA IS LASER HAZARD | LVEA | YES | LVEA IS LASER HAZARD \u0d26\u0d4d\u0d26\u0d3f(\u239a_\u239a) | 13:52 |
| 15:53 | FAC | Randy | X arm | n | X arm beam tube enclosure inspections | 21:48 |
| 16:48 | FAC | Kim | H2 build | n | Swifting | 17:00 |
| 20:37 | FAC | Tyler | Mids | n | Checks | 21:37 |
We recently noticed that the HWS live GUI wasn't working. In trying to troubleshoot this, I found that there are a few different instances of it - gitcommon area, userapps, personal alias's, and maybe others that I dont know about. They were either copies of the git code, pointed at different branches of the git repo, or modified versions, but none were consistent. I've now corrected the new path for the hws data directory (alog84865), and updated the git repo with the changes. The version in userapps I've just copied from this for now so it continues to work, but I'd like to change that in the future.
Long story short, it should work now.
Locked for 8.5 hours. The useism is still >90th percentile and our SEI_ENV node is in USEISM as a result. Range is stable.
FAMIS 31105
Looks like most things have settled out after our table inspection last Tuesday (alog87143), although PMC reflected power has been moving around a bit more than usual. ISS diffracted power also has been falling slightly, but right now it looks to have settled at around our target of 4%.
Wed Oct 01 10:07:13 2025 INFO: Fill completed in 7min 9secs
Looked at the last 6 locklosses from Observing.
Could see nothing much in all but one of them, 1443315128 where ETMX_L3 and DARM get noisy in the 70ms before LL, plot attached.
WP 12813
ECR E2400330
Modified List T2500232
The following SUS SAT Amps were upgraded per ECR E2400330. Modification improves the whitening stage to reduce ADC noise from 0.05 to 10 Hz.
| Suspension | Old | New | OSEM |
| PR2 M2 | S1100174 | S1100159 | ULLLURLR |
| PR2 M3 | S1100093 | S1100141 | ULLLURLR |
| SR2 M2 | S1100169 | S1100070 | ULLLURLR |
| SR2 M3 | S1100134 | S1000295 | ULLLURLR |
F. Clara, J. Kissel, O. Patane
(Since Jeff is out of town, I'm putting these in for these swaps.)
Here's the characterization data and fit results for S1100159, assigned to PR2 M2's ULLLURLR OSEMs. This sat amp is a UK 4CH sat amp, D0900900 / D0901284. The data was taken per methods described in T080062-v3, using the diagrammatic setup shown on PAGE 1 of the Measurement Diagrams from LHO:86807. The data was processed and fit using ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/ plotresponse_S1100159_PR2_M2_ULLLURLR_20250924.m Explicitly, the fit to the whitening stage zero and pole, the transimpedance feedback resistor, and foton design string are Optic Stage Serial_Number Channel_Number OSEM_Name Zero_Pole_Hz R_TIA_kOhm Foton_Design PR2 M2 S1100159 CH1 UL 0.0956:5.22 120.25 "zpk([5.22],[0.0956],1,""n"")" CH2 LL 0.0967:5.28 120 "zpk([5.28],[0.0967],1,""n"")" CH3 UR 0.0978:5.34 120 "zpk([5.34],[0.0978],1,""n"")" CH4 LR 0.0969:5.3 120 "zpk([5.3],[0.0969],1,""n"")" The attached plot and machine readable .txt file version of the above table are also found in ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Results/ Per usual, R_TIA_kOhm is not used in the compensation filter -- but after ruling out an adjustment in the zero frequency (by zeroing the phase residual at the lowest few frequency points), I nudged the transimpedance a bit to get the magnitude scale within the ~0.25%. shown in the attached results. Any scaling like this will be accounted for instead with the absolute calibration step, i.e. Side Quest 4 from G2501621, a la what was done for PR3 and SR3 top masses in LHO:86222 and LHO:84531 respectively.
(Since Jeff is out of town, I'm putting these in for these swaps.)
Here's the characterization data and fit results for S1100141, assigned to PR2 M3's ULLLURLR OSEMs. This sat amp is a UK 4CH sat amp, D0900900 / D0901284. The data was taken per methods described in T080062-v3, using the diagrammatic setup shown on PAGE 1 of the Measurement Diagrams from LHO:86807. The data was processed and fit using ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/ plotresponse_S1100141_PR2_M3_ULLLURLR_20250924.m Explicitly, the fit to the whitening stage zero and pole, the transimpedance feedback resistor, and foton design string are Optic Stage Serial_Number Channel_Number OSEM_Name Zero_Pole_Hz R_TIA_kOhm Foton_Design PR2 M3 S1100141 CH1 UL 0.0957:5.22 120.25 "zpk([5.22],[0.0957],1,""n"")" CH2 LL 0.0949:5.17 120.5 "zpk([5.17],[0.0949],1,""n"")" CH3 UR 0.0977:5.33 120.375 "zpk([5.33],[0.0977],1,""n"")" CH4 LR 0.0946:5.16 120.25 "zpk([5.16],[0.0946],1,""n"")" The attached plot and machine readable .txt file version of the above table are also found in ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Results/ Per usual, R_TIA_kOhm is not used in the compensation filter -- but after ruling out an adjustment in the zero frequency (by zeroing the phase residual at the lowest few frequency points), I nudged the transimpedance a bit to get the magnitude scale within the ~0.25%. shown in the attached results. Any scaling like this will be accounted for instead with the absolute calibration step, i.e. Side Quest 4 from G2501621, a la what was done for PR3 and SR3 top masses in LHO:86222 and LHO:84531 respectively.
(Since Jeff is out of town, I'm putting these in for these swaps.)
Here's the characterization data and fit results for S1100070, assigned to SR2 M2's ULLLURLR OSEMs. This sat amp is a UK 4CH sat amp, D0900900 / D0901284. The data was taken per methods described in T080062-v3, using the diagrammatic setup shown on PAGE 1 of the Measurement Diagrams from LHO:86807. The data was processed and fit using ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/ plotresponse_S1100070_SR2_M2_ULLLURLR_20250924.m Explicitly, the fit to the whitening stage zero and pole, the transimpedance feedback resistor, and foton design string are Optic Stage Serial_Number Channel_Number OSEM_Name Zero_Pole_Hz R_TIA_kOhm Foton_Design SR2 M2 S1100070 CH1 UL 0.0961:5.24 120.25 "zpk([5.24],[0.0961],1,""n"")" CH2 LL 0.0965:5.27 120.375 "zpk([5.27],[0.0965],1,""n"")" CH3 UR 0.0961:5.23 120.5 "zpk([5.23],[0.0961],1,""n"")" CH4 LR 0.0963:5.26 120.75 "zpk([5.26],[0.0963],1,""n"")" The attached plot and machine readable .txt file version of the above table are also found in ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Results/ Per usual, R_TIA_kOhm is not used in the compensation filter -- but after ruling out an adjustment in the zero frequency (by zeroing the phase residual at the lowest few frequency points), I nudged the transimpedance a bit to get the magnitude scale within the ~0.25%. shown in the attached results. Any scaling like this will be accounted for instead with the absolute calibration step, i.e. Side Quest 4 from G2501621, a la what was done for PR3 and SR3 top masses in LHO:86222 and LHO:84531 respectively.
(Since Jeff is out of town, I'm putting these in for these swaps.)
Here's the characterization data and fit results for S1000295, assigned to SR2 M3's ULLLURLR OSEMs. This sat amp is a UK 4CH sat amp, D0900900 / D0901284. The data was taken per methods described in T080062-v3, using the diagrammatic setup shown on PAGE 1 of the Measurement Diagrams from LHO:86807. The data was processed and fit using ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/ plotresponse_S1000295_SR2_M3_ULLLURLR_20250924.m Explicitly, the fit to the whitening stage zero and pole, the transimpedance feedback resistor, and foton design string are Optic Stage Serial_Number Channel_Number OSEM_Name Zero_Pole_Hz R_TIA_kOhm Foton_Design SR2 M3 S1000295 CH1 UL 0.0964:5.27 121.75 "zpk([5.27],[0.0964],1,""n"")" CH2 LL 0.0954:5.21 121.625 "zpk([5.21],[0.0954],1,""n"")" CH3 UR 0.0955:5.22 121.375 "zpk([5.22],[0.0955],1,""n"")" CH4 LR 0.0964:5.26 122 "zpk([5.26],[0.0964],1,""n"")" The attached plot and machine readable .txt file version of the above table are also found in ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Results/ Per usual, R_TIA_kOhm is not used in the compensation filter -- but after ruling out an adjustment in the zero frequency (by zeroing the phase residual at the lowest few frequency points), I nudged the transimpedance a bit to get the magnitude scale within the ~0.25%. shown in the attached results. Any scaling like this will be accounted for instead with the absolute calibration step, i.e. Side Quest 4 from G2501621, a la what was done for PR3 and SR3 top masses in LHO:86222 and LHO:84531 respectively.
M. Todd
This morning I used the early maintenance day to come in and make some measurements of IMC DOF Transfer Functions to ISS Second Loop RIN. I started by doing some OPS/GRD settings as I was here about an hour before the operator was set to come in.
I got through the first DOF measurement (DOF_1_P) without any hiccups; however a 7.0 earthquake from Philippines came in an unlocked us. Fortunately, I did not have to wait long for the IMC to relock and I proceeded with the other measurements.
DOF 1 and DOF 2 are relatively robust, but upon starting the DOF 3 measurement I had to lower the gain even more than anticipated, as the 1 and 3 Hz resonances are quite strong. The first run at this unlocked the IMC. After clearing the IMC DOF 3 P history, I let the IMC relock (it was having trouble) and continued with the subdued measurements.
I also tried to measure the UGF of each DOF loop, but was nervous about injecting that hard at the frequencies I suspected would contain the UGF.
Later, I will post a comment that tries to map the quiet time IMC contributions to the ISS Outer RIN in the regions we have enough coherence.
I'm adding a plot of projections of the quiescent noise in each IMC DOF loop to the ISS second loop. Note, I've cut off the TFs above 3 Hz due to coherence loss.
Since maintenance will start early next Tuesday, I've updated the PEM_MAG_INJ node to start its injections at 6:00am (13:00 UTC) and the SUS_CHARGE node will start at 6:25am (13:25 UTC). These should all be finished by 6:45am (13:45 UTC).
I've put both Tuesday morning automatic injection start times back to their usual with magnetic injections starting at 7:20am and in-lock charge at 7:45am (both in local time). Guardians have been loaded.
During Tuesday maintenance, we swapped the HAM6 AIP (Starcell). Note this annulus system is connected to HAM5 via the septum plate. We vented the lines with dry nitrogen and left a continuous nitrogen purge(~.3 psi) of the line during the pump swap. Nitrogen attached to HAM5 pump out port while HAM6 pump out port was left open to atmosphere.
No issues during the swap, annulus system is now pumping at both HAM5 & 6 ports with an aux cart and turbo pair. As of end of maintenance, the HAM6 cart was at ~3E-5 Torr, HAM5 cart at ~1E-4 Torr. These pumps will continue running until pressure is <1E-5 Torr at which point the ion pumps will be powered on.
Carts are placed on foam for isolation, and a piece of foam between the flex hose running up to HAM6 pump out port and HAM6 chamber. See attached pictures.
Work permit will be closed once pumps are disconnected from chambers.
Update.
IFO was out of lock due to an earthquake, I went in to the LVEA to check on the aux-carts pumping down on the annuli for HAM5 and HAM6. HAM5 aux-cart was good and pumping down on the annulus, however HAM6 aux-cart safety valve somehow managed to trip between yesterday and today, time is unknown as of now, I restored aux cart, and opened the valve. Aux-cart for HAM6 was reporting a dubious pressure number of 1.26 x 10-07 Torr.
After restoring pumping to HAM6 annulus, both aux carts are reporting more believable numbers.
(Jordan, TJ, Gerardo)
Late entry.
TJ powered ON the ion pumps over the weekend, that allowed for the pumps to reach very good vacuum pressure on the shared annuli system, then on Tuesday morning, Jordan isolated the annuli system for HAM5 and HAM6 from the mechanical pumps and turned off the aux carts.
A couple of hours later we removed the small can turbos, flex hoses and aux carts from the HAM5/6 area, to conclude the replacement of the HAM5 annulus ion pump body.
I continued today following the same process stated above.
(-9.38 mm - -9.93 mm)/ 1ct
= 0.55 mm/ct
(3.90 mm - 5.18 mm) / 1ct
= -1.28 mm/ct
(17.22 mm - 17.84 mm)
= -0.62 mm/ct
I reran the ITMX beam spot calibration following the same method described above, but this time I checked how the beam spot moved on both ITMX and ITMY when I changed the BS camera offset. Turns out, they give the same answer, so that's good.
(6.41 mm - 5.96 mm)/-1 ct
= -0.45 mm/ct
(11.26 mm - 11.70 mm)/ -1ct
= 0.44 mm/ct (-0.44 mm/ct for ITMY)