ITF remained locked in LOW_NOISE_3 with SCIENCE mode (Autoscience ON) for the whole shift; BNS Range ~54 Mpc.

Guard tour (UTC)
12:56 -> 13:39
16:23 -> 16:56
19:24 -> 19:56

DAQ
Daq_Sc_SR_Tolm_Send..Start_Min flag red on DMS since it registered a sudden increase (plot in fig.1) yesterday around 19:54UTC. On-call notified.

ITF Science mode for all the shift.

Guard tours (time in UTC)

4:24-5:10; 7:30-8:14;10:20-10:50

21:00 UTC ITF still in TROUBLESHOOTING while BS, PR and SR Vertical corrections were being adjusted
21:26 UTC ITF in PREPARE_SCIENCE. ISC on-call worked on BS TX full bandwidth on the hypothesis that the frequent unlocks had been brought about by glitches on BS
23:09 UTC  ITF in SCIENCE without BS TX full bandwidth to test whether an unlock would occurr (ITF_LOCK.py line 6178)
2:07 UTC ITF unlocked - Earthquake Mwp 5.8 (Kamchatka)
2:59 UTC ITF in SCIENCE
3:09 UTC ITF in TROUBLESHOOTING because SPRB corrections were driftig out of range. Contacted SBE on-call
3:56 UTC ITF in SCIENCE

Guard Tours (UTC)
00:07 - 00:46  --> at around 00:20 a loud noise was heard, the guard reports having seen a single firework-like shot coming from outside the fence between CEB and NEB.
2:05 - 2:45
3:09 - 3:36
4:24 - 

ISC
(20-09-2025 16:00 - 21-09-2025 23:22) On site
Status: Ended
Description: locking problems and ITF instability at LN3. Commented ITF_LOCK.py line 6178 (disabled BS TX full bandwidth)

SBE
(21-09-2025 03:09 - 21-09-2025 03:56) From remote
Status: Ended
Description: SPRB corrections out of range

SUSP
(20-09-2025 19:30 - 20-09-2025 21:26) From remote
Status: Ended
Description: Vertical corrections for PR, SR, BS, WI - Coil_close_to_saturation. Adjusted.

First intervention (5:30 - 7:00)

I was called today at around 5:30 local time because the vertical corrections of the PR were very close to saturating. The ITF was locked, but as I started operating with the vertical motors I couldnt keep the lock. After fixing the PR, I decided to intervene on the BS and NI too since they were also not far from saturating.

All operations ended at around 7:00 local time.

EDIT: Second Intervention (21:40 - 23:30)

I was then called again at around 21:40 local time again for the same vertical saturations, this time of the SR. I decided to also correct a bit more the PR and BS. The WI is flagged as close to saturating, but the trend of the latest period suggests it is correcting itself, so I decided not to intervene.

Operations ended at around 23:30 local time.

ITF found DOWN in TROBLESHOOTING mode due to two a problems:
SBE
SPRB horizontal position recovered from remote bu Bulten at 13:06 UTC.
ISC
Strange behavior on correction signals of the green laser. ISC expert with DAQ expert fixed the problem. See dedicated entry. Unfortunately ITF unlocked sistematically at ALIGNING_DRMI.

TROUBLESHOOTING mode set again. ISC OnCall performed a good realignment of the green, then the lock acquisition started again. ITF relocked after the usual cross-alignment in ACQUIRE_DRMI.
17:20 UTC - SCIENCE mode. Unfortunately, at 17:23 UTC, ITF unlocked again (TBC) several times at various steps. Finally ITF locked at LN3 in a stable way.
During the relock, at 18:38 UTC, I had to re-enable vbias and open shutter for B1p_QD1:.
19:27  UTC SCIENCE mode set.
19:30 UTC - CALIBRATION mode set:
- check hrec started but unfortunately interrupted due to unlock!
TROUBLESHOOTING mode set again. ISC OnCall contacted again...

Guard tour (UTC):
13:26 - 14:00
16:30 - 17:06
19:38 - 20:14

ISC
(20-09-2025 16:00 - 20-09-2025 ) On site
Status: On-going
Description: locking problems and ITF instability at LN3. Check in progress...

SUSP
(20-09-2025 19:30 - ) From remote
Status: On-going
Description: Vertical corrections for PR, SR, BS, WI - Coil_close_to_saturation. Check in progress...

ITF found in Troubleshooting mode with SUSP on-call working from remote in order to recover the vertical corrections of the suspensions. Intervention completed at around 5:00 UTC; the ITF relocked at the first attempt and Science mode was set at 5:50 UTC.

The ITF unlocked at 11:56 UTC; after that we had a problem with the NE ALS which prevented to lock.

At 12:27 UTC I set Troubleshooting mode and I contacted the ALS on-call; taking advantage of this stop I contacted also the SBE on-call to check and recover the status of SPRB because the horizontal corrections were saturating.

Troubleshooting in progress....

SBE

At 5:00 UTC I recovered the vertcial position of SPRB.

HVAC

The temperature of the CB hall stabilzed at a lower level.

draft in progress

21:00 UTC ITF found in SCIENCE
3:27 UTC NI_Vert, PR_Vert amd BS_Vert saturated (same issue as the past few days). Intervention from remote by Vacatello
3:34 UTC ITF in TROUBLESHOOTING
5:00 UTC oncall intervention still ongoing

Guard Tours (UTC)
22:03 - 22:43
00:30 - 1:21
2:49 - 3:24

SUSP
(20-09-2025 03:25 - ) From remote
Status: On-going
Description: PR Vert F0 corrections (Vacatello)

ITF founf locked at LN3 in SCIENCE mode.
13:53 UTC - ADJUSTING mode set in order to allow Cavalieri to restart IMMS_17 in CEB. SCIENCE mode at 14:02 UTC.
ITF unlocked at 14:20, 16:30, 17:44 UTC due to some earthquakes occurred in Russia. In both two first relocks I had to perform the cross-alignment in AQUIRE_DRMI (SR tx and ty) and in both occasions I had to launch 2 times MISALIGNED on SUS_PR metatron node.

Guard Tours (UTC)
18:00 - 18:41
19:30 - 20:19

ITF found in Science mode.

At 6:54 UTC ITF in Troubleshooting mode to:

• Recovery of SR, WI and PR vertical corrections ;
• recover EIB actuator ;
• replace the ACS controller of the CB (Davide and Federico) ;
• Recover the vertical position of SPRB (me);

At 10:20 UTC ITF back in Science mode.

INF/Computing

At around 12:19 UTC the IMMSserver lost the connection with the module env-imms17 (192.168.229.47); the module does not answer to the ping. The module provides temperature for the CB, CB clean rooms and for the DAQ; the related flags are dark-grey (meaning corrupted data) in the DMS. Experts have been informed by mail.

Three on-call interventions since yesterday, September 18th

First intervention (21:30–22:30 local time)
While monitoring the suspension subsystem yesterday, I noticed that the SR coils were close to saturation.
Together with M. Was, we decided to proceed with adjusting the correction values, despite the ITF being locked.
An earthquake occurred shortly before we started. After switching the ITF to earthquake mode, I was able to reduce the correction values on the PR tower.
The suspension subsystem remained unaffected by the earthquake, and the ITF could enter Science Mode around midnight.

Second intervention (03:00–03:40 local time)
During the night, the operator contacted me because the PR coils were again close to saturation.
Although the ITF was locked, we decided to proceed anyway since both LIGO Livingston and Hanford were down.
As expected, the ITF unlocked during the operation. After completing the adjustments on the PR tower, I also corrected the WI, whose values were not critical but could have caused issues later.

Third intervention (09:00–10:30 local time)
This morning, the same issue occurred on the WI, PR, and SR towers.
The WI had moderately high vertical corrections, which I adjusted quickly.
For the PR and SR, however, the coils had fully saturated. To recover them, it was necessary to download the DSP cards and manually restore the vertical setpoints of the suspensions.
V. Boschi and P. Ruggi helped me resolve this issue as quickly as possible.

Following the recent HVAC failure in the Central Building and its impact on the etalon control (ref. #67732), we report here the usual correlation analysis between the ~30-minute glitches (formerly referred to as 25-minute glitches) and several temperature signals associated with the etalon, in particular the temperature at the bottom of the North Input (NI) tower.

Figure 1 is analogous to those presented in previous entries: #63147, #63479, #66142. The plot now also includes the Central Building temperature (in grey), which shows clear fluctuations starting on 13 September. No obvious similarity is observed between the CEB temperature and NI_BOTTOM temperature, except for the fact that both began to oscillate significantly from 13 September onwards, likely due to the etalon temperature active control. It was not possible to align the two series in order to assess a possible time delay.

Overall, this quick analysis confirms the established correlation between the NI_BOTTOM temperature and the glitch rate (orange and red curves), which appears much stronger than any direct link with the CEB temperature.

Conclusion: the source of these 25-minute glitches remains thermally coupled to NI_BOTTOM.

21:00 UTC ITF found in EARTHQUAKE MODE - LOCKING_ARMS_IR
00:07 UTC  ITF in SCIENCE
00:58 UTC PR_Vert F0 Coil V1 and V2 saturated. M. A. Palaia (SUS) warned me at the beginning of the shift that this could occurr and asked me to contact her if it happened, so I called her.
1:06 UTC ITF unlocked - TROUBLESHOOTING to fix SR_Vert and WI_Vert F0 corrections (procedure by Palaia as prescribed by Was yesterday afternoon)
1:46 UTC intervention ended. Relocking required closing of SR LC and rearming Vbias of B1p_QD1 and B1p_QD2 (seismic activity again)
3:11 UTC ITF in SCIENCE

Guard Tours (UTC)
22:33 - 23:11
1:05 - 1:41
3:22 - 4:09

SUSP
(19-09-2025 00:53 - 19-09-2025 01:46) From remote
Status: Ended
Description: PR_Vert F0 Coil V1, V2 saturated (M. A. Palaia)

ITF found locked at LN3 in SCIENCE mode.
At 15:00 UTC started the planned ISC activity on 8MHz increase and SR tx gain increase carried out by Boldrini and Mantovani.
15:07 UTC - COMMISSIONING mode set. Activity concluded at 17:00 UTC.
17:21 UTC - CALIBRATION mode set.
17:33 - 18:27 UTC - planned LSC injection script long test (300s) - T_PADD = 300

SCIENCE mode set.

At 19:12 UTC ITF unlocked due to a strong earthquake in Russia (fig1). EARTHQUAKE mode set.
NE_ID, PR_ID, SIB2, EIB, SPRB, SNEB, SWEB, SDB2 loops opened. Properly closed. Relocking in progress...

ACS
Under suggestion of Was I contacted Soldani to gave me instructions to act on the CEB cold valve and set it from 20 to 15. Action done at 19:34 UTC (fig2).
SUSP
Meanwhile Palaia recovered the PR vertical position.
DAQ
TelescreenArt VPM process crashed. Properly restarted at 19:40 UTC.

Ego truck passages around CEB (UTC):
14:15 - 14:25

We have done two tasks : 8MHz increase from -6dB to 6dB and SR tx gain increase from 2 to 10.

8MHz:

the first trial has been ruined by a glitch on the SR tx error signal, but we have still used that lock part for getting the correct scaling of the IB tz and ty gains.

Then we have repeated the same action by opening the angular controls for SR.

In  Figure 1 the comparison from -6dB (purple) and 6dB blue. It is visible that the SNR has been improved as expected. In Figure 2 we can see the trend.

SR tx gain:

during the recovery of the alignment after the glitch of SR tx error signal we profited for testing the higher gain. It worked properly. We did also in an aligned ITF a step of 0.5urad to test the new loop convergence speed. see fig 3.

After that we manually unlocked to test the new lock acquisition with the following changes

ITF_LOCK.ini

lline 166 pr_x_gain  from 30 to 5

line 168 pr_y_gain from 15 to 1.5

line 182 mod_ampl_8mhz from -6 to 6

line 493 sr_tx_gain from 2 to 10

ITF found in Troubleshooting mode.

At around 6:30 UTC M.Was recovered the vertical position of SR (leaving SDB1 floating setpoint not enableb) and we started to relock.

At 8:03 UTC ITF in Science mode; from 8:06 UTC to 8:14 UTC and from 8:33 UTC to 8:48 UTC ITF in Adjusting mode to allow Davide to perform a check of the CB ACS controller.

The temperature of the CB is not yet under control, see attached plot.

During the maintenance (Sept 16), two sets of values were sent to the DAC channel ENV_Noise_CEB_DetLab_speaker_1:

• First set: 0.1 to 0.5 (step 0.1)

• Second set: 0.01, 0.03, 0.04, 0.05

Figures 1 and 2 show the injections performed. During the test with the first set, the microphone ENV_EDB_MIC was saturating (see Figure 2). The corresponding acoustic noise generated inside the lab is reported in Figure 3 (mic saturation observed for frequencies < 40 Hz) and Figure 4.

This morning, taking advantage of the ITF in Troubleshooting mode, the DET acoustic injection via the METRATON node was also tested, and it worked properly.

Since the recent increase in the INJ-HVAC flow rate (from 30 May to 4 June 2025), a new noise feature has become visible on the microphones and accelerometers located on the Laser Bench and the External Injection Bench inside the Laser Lab.

The noise manifests as a characteristic doublet "bump", recurring approximately every 6 minutes. This suggests a mechanical or fluid-dynamic origin, potentially linked to the altered HVAC regime.

Before the intervention, the air flux was stable at 10 m³/h. After the change, it now oscillates between 20 and 60 m³/h. This fluctuation appears correlated with the observed noise.

• Has this change been requested by someone?

• Would it be possible (and advisable) to revert to the previous setting to mitigate the noise?

Here the FIgure referred to in the entry.

The following report has been submitted to the On-call interface.

On-call events -> Interferometer Sensing & Control

Title: B1p beam outside the camera

Author(s): casanueva

Details:

Tonight I was called by the operator, following the instructions of the SUSP SSM. Allegedly the marionetta values of the SR mirror were outside the usual values and I was contacted to put the SR back to its nominal position, since the beam was almost completely outside of the B1p camera. Since I was already awake, I took a look to the trend data of the marionetta values of the SR, even if this is not a specific ISC task. I checked the "misaligned" values of the last lock, but it looked to me that the SR was int he right position (within 2urad), and so this couldn't be the reason for such a displaced beam in the camera (when in nominal conditions we can misalign the SR by 10s urads and we still see the complete beam in the camera).

So I profited and I tried to take a look to the position of the SR mirror in vertical and horizontal. it looked to me that vertically the mirror was in a different position (around 40ums), so this could explain why the beam was so out while the marionetta was still showing the same values as usual. see Figure 1. The SR_Vert flag in the DMS was also red, showing some excursion in the vertical position of the SR. However, I am not familiar with the SR DSP card, so I didn't feel like moving it myself. I asked the operator to contact the SUSP on-call to give a hand with it and to call me after if this didn't solve the problem.

* Note that any files attached to this report are available in the On-call interface.

ITF found DOWN in TROUBLESHOOTING mode, with SUSP on-call Palaia working on recovery of PR. At 21:39UTC, as soon as light flashes became visible on B1p camera I reset DET_MAIN node to INIT so it could finally reach SHUTTER_CLOSED state. At 23:08UTC both PR and SR suspensions were recovered with the help of Boschi and Ruggi. At 23:29UTC ITF achieved LOCKED_ARMS_IR thanks to Magazzu's intervention on PR X, Y set points. At 23:59UTC Magazzu also recovered SBE_SPRB_ACT_F0V position (fig.1). At 00:20UTC, as suggested by Boschi, I contacted ISC on-call Casanueva due to beam spot on B1p camera appearing almost outside upper bound (fig.2) preventing me from performing cross alignment of CITF. DET on-call unreachable. Waiting for recovery of SR Vert and LC, ITF left parked in LOCKED_ARMS_IR.

Guard tour (UTC)
22:36 -> 23:16
01:00 -> 01:38
01:08 -> 01:49

Following Michal’s input, I repeated the standard correlation study for Scattered Light (#64022, #64041) during the period of elevated microseismic noise (sea activity) between September 10-11, in order to identify the dominant residual source after the intervention on the West End baffle.

As a first step, I compared the glitch rate (frequency < 50 Hz, SNR > 5, noting that this rough cut also includes other types of glitches) with the BRMS between 0.1 and 1 Hz from ENV_CEB_SEIS_W, both in this recent period and during another high microseism episode, December 7-8, 2024. The current rate remains below ~8 glitches/min even with seismic velocity above 3 µm/s. In contrast, last December the rate was nearly double for comparable microseism levels. Refer to Figures 1 and 2.

I then repeated the usual analysis to search for correlations. The attached list shows the most correlated channels, along with plots of some representative cases. All channels with correlation > 0.2 are associated with the West End, F0, and F7, as in the past. A weaker correlation was also identified with some North End channels, such as Sa_NE_F0_LVDT_V, though visual inspection suggests no clear similarity between this channel’s velocity and the glitch frequency (see Fig. 5).

Time permitting, the analysis could be extended to other periods of strong sea activity. For now, however, the data support a reduction in scattered light glitch rate while confirming the West End as the primary source.

ITF found in LOW_NOISE_3 and in Science Mode. 
During the afternoon the Vertical correction of both SR and PR increased. At 17:23 UTC the SR coils started to saturate, but the ITF kept the lock. In the meantime I've contacted the SUSP Oncall (Palaia) and agreed to proceed with the recovery at the unlock.
The ITF remained locked, but also the PR coils were close to saturation. At 19:52 UTC I set the ITF in Troubleshooting Mode to allow Palaia to start the recovery, the ITF unlocked at 20:27 UTC.
ITF left in DOWN state, recovery in progress.

SBE
The SPRB Position loop opened at 20:27 UTC during the recovery of PR. Loop left open until the end of the recovery.

DET
The node DET_MAIN went in UNKNOWN state after the unlock at 20:27 UTC. Because there's no light on B1p due to the recovery of the PR, for the moment it's not possible to restore it.

Guard Tour (UTC)
17:57 - 18:29
19:55 - 20:29