Marc, Oli
In 87713 it's noted that some of the strange behavior we've been seeing with the locks seem to be related to the ETMY L2 stage. The ETMY L2 satamp was swapped out on Oct 14th from S1100137 to S1100127 as part of the ECR E2400330 upgrade (87469). So, even though we were seemingly doing fine with this ETMY L2 satamp, we decided to swap it out this morning to see if that is the cause of our issues. Coincidentally, the spare satamp that we have available that was modified for ECR E2400330 and that Jeff had characterized was the satamp that had come from ETMY L2, S1100137. So we decided to put that one back in - it was fine before, although it obviously has now been modified for the satamp upgrade. So it's not been swapped back to exactly what it was before, but this is the closest we can get!
Marc and I took S1100137 down to EY and swapped out S1100127 with S1100137. I edited the fitresults file for S1100137 to work for ETMY L2 and replaced the previous OSEMINF 5.3:0.1 compensation filters to be the best possible compensation filters for this new satamp.
Updating compensation filters
$ py satampswap_bestpossible_filterupdate_ECR_E2400330.py -o ETMY_L2
All updated filters grabbed for ETMY
ETMY L2 UL compensation filter updated to zpk([5.25],[0.0959],1,"n")
ETMY L2 LL compensation filter updated to zpk([5.21],[0.0953],1,"n")
ETMY L2 UR compensation filter updated to zpk([5.18],[0.0949],1,"n")
ETMY L2 LR compensation filter updated to zpk([5.21],[0.0955],1,"n")
write /opt/rtcds/userapps/release/sus/h1/filterfiles/H1SUSETMY.txt
Done writing updated filters for ETMY
Swap timeline
| Date | Serial Number | Whitening zp |
| Before Oct 14th 2025 | S1100137 | 10:0.4 |
| Oct 14th 2025 | S1100127 | 5.3:0.1 |
| Oct 24th 2025 | S1100137 | 5.3:0.1 |
Satamp characterization data
Here's the characterization data and fit results for S1100137, assigned to ETMY L2'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_S1100137_ETMY_L2_20251020.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 |
|---|---|---|---|---|---|---|---|
| ETMY | L2 | S1100137 | CH1 | UL | 0.0959:5.25 | 120.875 | zpk([5.25],[0.0959],1,"n") |
| CH2 | LL | 0.0953:5.21 | 121.625 | zpk([5.21],[0.0953],1,"n") | |||
| CH3 | UR | 0.0949:5.18 | 121.625 | zpk([5.18],[0.0949],1,"n") | |||
| CH4 | LR | 0.0955:5.21 | 121.5 | zpk([5.21],[0.0955],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/
2025-10-20_UKSatAmp_S1100137_D0901284-v5_fitresults.txt
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), Jeff 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.
This swap seems to have fixed the saturation problems, great work!
Fri Oct 24 10:10:02 2025 INFO: Fill completed in 9min 58secs
To continue with the "what has changed since Monday" I have created the SDF reports. For now I've just concentrated on the OBSERVE.snap settings changes.
Models with changed settings over this time period: h1alsex h1alsey h1asc h1ascimc h1iscex h1iscey h1isietmy h1lsc h1omc h1suspr3 h1sussr3
There are approximately 400 settings changes.
Full details available in /ligo/home/david.barker/tuesdaymaintenance/23oct2025/sdf/observe
I can only see dark offset updates except for:
inp1 gain changed from 2 to 1 (which Elenna said was reverted):
-H1:ASC-INP1_P_GAIN 1 -2.00000000000000000000e+00 1
+H1:ASC-INP1_P_GAIN 1 -1.00000000000000000000e+00 1
changes to ISI-ETMY_ST2_BLND which I assume are to do with BRSY not working,
The following changes in h1lsc:
-H1:LSC-POP_A_RF45_I_SW1S 1 4.12400000000000000000e+03 0xffffffff
+H1:LSC-POP_A_RF45_I_SW1S 1 1.05200000000000000000e+03 0xffffffff
-H1:LSC-POP_A_RF45_Q_SW1S 1 4.12400000000000000000e+03 0xffffffff
+H1:LSC-POP_A_RF45_Q_SW1S 1 1.05200000000000000000e+03 0xffffffff
-H1:LSC-MICH2_GAIN 1 1.00000000000000000000e+00 1
+H1:LSC-MICH2_GAIN 1 2.00000000000000000000e+00 1
-H1:OMC-REFL_A_LF_SW2S 1 1.55600000000000000000e+03 0xffffffff
+H1:OMC-REFL_A_LF_SW2S 1 1.55200000000000000000e+03 0xffffffff
Changes related to PR3 amd SR3 estimator that Olli is not suspicious of as it it all off.
Edit: Don't think any of this is suspicious.
We had a lockloss at 17:03 UTC that has the same "pulse" behavior noted by Jennie and Oli yesterday. This pulses can be seen in the DARM loop, on the L3 master out, and in the EX and EY L2 master outs. These pulses are about 5.8 Hz in frequency.
I'm going to use this post to keep running notes of the 1 Hz investigations:
DHARD P at 1 Hz attached.
We edited the thermalization guardian so that it should set the csoft p gain to 20 only once, after 30 minutes (as before), then after that a user can change it as they wish.
We have been getting saturation warnings on EY after going through the lownoise coil drivers state. We finally tracked it down to the R0 F2 and F3 drivers. The reaction chain length drive (aka reaction chain tracking) is causing these saturations. This servo is run using the L2 OSEMs as a witness to then drive the R0 chain to follow the main chain. I turned off the length drive and the saturations stopped. When I turn it back on it continues to saturate.
The only recent change I can think of is the L2 satamp swap on all the test masses.
Adding a comment: We've only had these saturations intermittently the last few days, in this lock it is now contiuous if the R0 tracking is on. The sat amp swap happened Oct 14th, so perhaps this is some delayed consequence of the swap.
I was also reminded that the EY tiltmeter is possibly not performing as well as it can either as of Tuesday this week.
After the ETMY L2 satamp was swapped back, we no longer get saturations on EY with R0 tracking on!
Because we continue to have issues with the lownoise state of DHARD P (1 Hz ring up), I have commented out both DHARD P lownoise steps in LOWNOISE_ASC. This includes the engagement of FM4 (lownois reshape with low pass) and FM8 (boost). These steps are done separately. This means that we can safely run the LOWNOISE_ASC guardian state, there will just be a little more noise until we can resolve the DHARD P issues.
We had a small mains power glitch 17:25:25 Thu 23 Oct 2025 PDT. It was only reported by the OSB GC UPS.
TITLE: 10/24 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
SEI_ENV state: USEISM
Wind: 8mph Gusts, 6mph 3min avg
Primary useism: 0.04 μm/s
Secondary useism: 0.62 μm/s
QUICK SUMMARY: H1 was down overnight due to ongoing locking issues. I'll start by running through an initial alignment while I get caught up on events of the past couple days.
After confirming it was damping well over mulitple locks I added the new settings of ITMX13 to lscparams and reloaded the GRD, -30 phase with a gain of -1.0.
TITLE: 10/24 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
INCOMING OPERATOR: Tony
SHIFT SUMMARY: Microseism is still slowly trending up, I got up past MAX_POWER twice, I confirmed the Roll mode damping works at 62Ws.
LOG: No log.
Lock#1
Lock#2
I modified Oli's script make_EST_model.m that gets the OSEM estimator filters into the front-end models. This script is now the preferred way to get any estimator model filters into the real-time computers. The change was made to add failsafes to avoid further errors on the translation of fitted filters into foton ( see LHO: 87689 ).
For the script to work, any .mat files with estimator filters must have the following syntax:
The format for the filters can be seen in any of the .mat files listed below that live in (svnroot)/sus/trunk/HLTS/Common/FilterDesign/Estimator/. The files come with a README that indicates at how the fits inside were created
est_model_H1PR3_L_2025-10-07.mat -- contains slightly tweaked versions of the PR3 L (and P) models reported in [LHO: 87593]
est_model_H1PR3_P_2025-10-07.mat -- contains slightly tweaked versions of the PR3 P (and L) models reported in [LHO: 87593]
est_model_H1PR3_Y_2025-08-19.mat -- contains the PR3 Y fits from [LHO: 86563]
est_model_H1SR3_L_2025-10-07.mat -- contains slightly tweaked versions of the SR3 L (and P) models reported in [LHO: 87612]
est_model_H1SR3_P_2025-10-07.mat -- contains slightly tweaked versions of the SR3 P (and L) models reported in [LHO: 87612]
est_model_H1SR3_Y_2025-08-05.mat -- contains the cleaned SR3 Y fits from [LHO: 86366]
These are the new .mat files that have the current OSEM estimator models. Until further notice, all previously existing .mat and .m files for OSEM estimator models/fits have been deprecated. We will later talk with Oli to standardize the addition of the OSEM estimator blends.
The updated make_EST_model.m, as well as the rest of the .mat files with the new syntax have been updated to the SUS svn under revision 12754.
Maybe the roll mode we're fighting today isn't ETMY after all?
In the attached plot, the traces are 20 min apart, and you can see that the mode we were watching at 13.75 Hz gets bigger. Throughout this time, Rahul was changing setttings on SUS-ETMY_M0_DARM_DAMP_R, trying to get it to stop increasing. However, when the output of the damping filter was a very small number of counts, we weren't really seeing big changes in the slope of the increase in the monitor filter H1:SUS-ROLL_ETMY_RMS_LOG10_OUTMON. When Rahul increased the gain to 1200 (from the original of 40), we started ringing up a different mode quite quickly. That other mode is 13.94 Hz.
13.94 Hz doesn't match any of the roll mode monitor filters we have in place (second attachment) according to the names of the filters. But, maybe this means that ETMY is actually at 13.94 Hz, and some other optic is at 13.75 Hz? Back in July (alog 84982 that Elenna pointed me to), we originally thought that 13.7 Hz was ETMX, but had found at that time that actuating ETMY seemed to improve things.
Anyhow, we may also consider trying to actuate on other optics, to see if we can do anything to that 13.75 Hz mode? While the monitor filters are all quite narrow (as they should be), the actuator filters appear to all be the same between the optics.
Rahul is working to identify which optic this problematic 13.75 Hz mode is, and so has been actuating on ITMY. We're now seeing a mode at 13.87 Hz with the ITMY actuation, so I think ITMY is absolved from being the problematic optic.
Attached plot is during ITMY actuation.
I am able to ring up 13.75 Hz by actuating on ETMX roll - see attached plot.
I was able to ring up this mode and then damp it down using the following settings - FM2+FM3+FM4, Gain -200 (-60 deg phase filter) for ETMX @53W input power. This needs to be checked at higher power and at NLN.
As per Elenna's suggestion - we will start with damping ITMY roll mode first.
ETMY roll mode gain will be set to zero for the next lock.
WP 12836
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 |
| ETMX L2 (PUM) | S1100146 | S1100119 | ULLLURLR |
| ETMY L2 (PUM) | S1100137 | S1100127 | ULLLURLR |
| ITMX L2 (PUM) | S1100135 | S1100118 | ULLLURLR |
| ITMY L2 (PUM) | S1000277 | S1100148 | ULLLURLR |
F. Clara, J. Kissel, O. Patane
Here's the characterization data and fit results for S1100148, assigned to ITMY L2'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_S1100148_ITMY_L2_ULLLURLR_20250917.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 |
|---|---|---|---|---|---|---|---|
| ITMY | L2 | S1100148 | CH1 | UL | 0.095:5.19 | 120.5 | zpk([5.19],[0.095],1,"n") |
| CH2 | LL | 0.0957:5.24 | 120.0 | zpk([5.24],[0.0957],1,"n") | |||
| CH3 | UR | 0.0958:5.24 | 120.125 | zpk([5.24],[0.0958],1,"n") | |||
| CH4 | LR | 0.0967:5.28 | 120.375 | zpk([5.28],[0.0967],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/
2025-09-17_UKSatAmp_S1100148_D0901284-v5_fitresults.txt
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), Jeff 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.
Here's the characterization data and fit results for S1100119, assigned to ETMX L2'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_S1100119_ETMX_L2_ULLLURLR_20250916.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 |
|---|---|---|---|---|---|---|---|
| ETMX | L2 | S1100119 | CH1 | UL | 0.0949:5.19 | 120 | zpk([5.19],[0.0949],1,"n") |
| CH2 | LL | 0.0971:5.32 | 120 | zpk([5.32],[0.0971],1,"n") | |||
| CH3 | UR | 0.0964:5.27 | 120 | zpk([5.27],[0.0964],1,"n") | |||
| CH4 | LR | 0.0957:5.23 | 120 | zpk([5.23],[0.0957],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/
2025-09-16_UKSatAmp_S1100119_D0901284-v5_fitresults.txt
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), Jeff 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.
Here's the characterization data and fit results for S1100118, assigned to ITMX L2'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_S1100118_ITMX_L2_ULLLURLR_20250916.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 |
|---|---|---|---|---|---|---|---|
| ITMX | L2 | S1100118 | CH1 | UL | 0.0966:5.27 | 120 | zpk([5.27],[0.0966],1,"n") |
| CH2 | LL | 0.0961:5.25 | 120 | zpk([5.25],[0.0961],1,"n") | |||
| CH3 | UR | 0.0963:5.26 | 120 | zpk([5.26],[0.0963],1,"n") | |||
| CH4 | LR | 0.097:5.3 | 120 | zpk([5.3],[0.097],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/
2025-10-14_UKSatAmp_S1100118_D0901284-v5_fitresults.txt
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), Jeff 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.
Here's the characterization data and fit results for S1100127, assigned to ETMY L2'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_S1100127_ETMY_L2_ULLLURLR_20250916.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 |
|---|---|---|---|---|---|---|---|
| ETMY | L2 | S1100127 | CH1 | UL | 0.0963:5.26 | 121.25 | zpk([5.26],[0.0963],1,"n") |
| CH2 | LL | 0.0958:5.24 | 121.25 | zpk([5.24],[0.0958],1,"n") | |||
| CH3 | UR | 0.0952:5.2 | 121.25 | zpk([5.2],[0.0952],1,"n") | |||
| CH4 | LR | 0.0954:5.21 | 121.25 | zpk([5.21],[0.0954],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/
2025-09-16_UKSatAmp_S1100127_D0901284-v5_fitresults.txt
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), Jeff 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.
ITMY L2 (PUM) Sat Amp S1100148 installed on 10/14/2025. Replaced on 10/16/2024 with S1100080.
https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=87515