ITF found in LOW_NOISE_3 and in Science Mode. From 7:06 UTC to 7:07 UTC I set the ITF in Adjusting Mode under request of Was to set the SR TX offset to zero (see report #68150).
ITF left locked.

Updating one more/last time that plot to extend significantly the timescale covered.

Updating one more/last time that plot to cover a long timescale after the June fix. 

Figure 1. During last night the BNS range has been slowly fluctuating between 45Mpc and 55Mpc. The BNS range trend look almost identical to the trend of SR MAR TY and of the DARM optical gain measured by Hrec. Whenver SR TY is low the BNS range and optical gain are low. This morning around 7:05UTC I have put the SR TX offset to zero, as that will make SR TY higher to keep the same value of the DCP. This seem have been effective at increasing the DARM optical gain, and making it stable, and at reducing the SR TY fluctuations. 

However, it has been that great at making the BNS range better. It dropped at 08:00 UTC. The B1p QD 50MHz out of loop signals, (QD2 V and QD1 H) change mean value and start to have more glitches about at the same time. 

Yesterday evening, we notice that the pre-alignment of the input beam on the ITMs was quite wrong with all the DoF out of several mm. I profited of the SDB1 F0 intervention to reduce the misalignment by moving the PR in X/Y. I didn't recover the best position to avoid saturation on the BPC signals. 

Moreover, at the end of the maintenance, Francesco had to work on the input beam (by moving the PR X/Y) in order to lock the arms. Moreover, once locked in CITF and LN3, I noticed that the SR_TX alignement was 15µrad far away from the value of the last lock of the early morning. Checking back in the data, this seems to happen only after the maintenance.

One possibility is that this effect is due to the hybrid strategy of the IMC/BPC alignment that differs from INJ standalone and once the ITF is fully locked. Indeed, the BPC setpoints were setted to the value of the summer period, which were quite different from the present alignment of the IMC, in particular in the TX DoF (setpoint was 9, present value ~ -5). However, there should be some integrators in the DSP in order to avoid any jump during the switch between the two conditions. 
I'll check with Paolo if there is some bug in the control actuation.

In order to understand if part of the loud glitches visibile in Hrec during the last days are due to some PSTAB issues (similar to what happened few months ago), during the yesterday maintenance we tried to check the alignment of the AOM on the laser bench (PSTAB actuator) with the PMC alignment as figure of merit. 
However, we couldn't improve the latter using only the mirror before the AOM (i.e. touching only the tilt). We also checked if the PMC alignment was good, again with only the mirror in front of the entrance (tilt), with the same result: the misalignment remained at around 1.3-1.5%. The most sensitive DoF seemed to be the vertical tilt.

At the end of the intervention, the PMC transmission and PSTAB corrections are a bit worse than before (see fig. 1).

A better way to proceed, would be to realign looking directly at the first diffracted order with a power meter, maybe re-checking also the alignment of the whole optical path starting from the NEOvan. But, this would require much more time and may be done after the end of the O4c run. 

ITF remained locked in LOW_NOISE_3 for the whole shift with SCIENCE mode (Autoscience OFF). BNS Range unstable, oscillating between 52-44 Mpc.

The purpose of this shift was to test a set of values sent to the DAC channel ENV_Noise_CEB_EE_room.
Only two values were tested due to some issues with the lock stability.

Each injection lasted 180 seconds and was performed via the METATRON node.

Some comments are reported below:

• The ITF unlock was not caused by the acoustic injections (see Figure 1).

• Figure 2 shows several monitoring signals from the BPC (BsX_*), the microphones, and their coherence with Hrec, while Figure 3 displays the same signals with a zoom around 800 Hz. At this frequency, Hrec exhibits a coherent structure with some of the BPC signals, suggesting a possible coupling path.

• Figure 4 shows the DAC noise levels.

• Figures 5 and 6 show the acoustic spectra during the injections.

• Figures 7 and 8 show the vibration of the benches during the injections.

• Figure 9 shows the structures excited in Hrec in the frequency range 100–1000 Hz.
  
   

14:00 UTC ITF found in SCIENCE, range 45Mpc
14:54 UTC unlock, troubles relocking (see Spinicelli's entry about BPC setpoint)
15:00 UTC - 21:00 UTC COMMISSIONING - ENV noise injections skipped, INJ acoustic injections and WE in-vacuum wireless test partially performed (last one needs a follow up during the next maintenance). During commissioning the following events happened:

1. LN3 achieved at 16:02
2. WE in-vacuum wireless test (68142 Ballester, partially, 16:45 UTC - 17:30 UTC)
3. INJ acoustic injections (68143 Fiori, Tringali, partially, 17:45 UTC - 17:57 UTC)
4. unlock at 17:59 UTC
5. SDB1 F0 recovery (68141 Baratti, 19:10 UTC)

20:26 UTC ITF in TROUBLESHOOTING due to relocking issues
21:15 UTC ITF in SCIENCE. Range 53 Mpc. The lock was achieved through the following steps:

• alignment of PR and SR
• MICH offset (40, 400s) started at 400 of CARM_NULL timer
• at the end of CARM_NULL timer, SR TX SetPos +2 (from 2.72 to 4.72) RampTime 60 s
• during LOCKING_MC_DARM_B1_PD3, as soon as SDB2_B1p_DC reached 0.03 mA, SR TY SetPos +2 (from -233 to -231) RampTime 60 s

note: TCS_WI_CO2_CH_PWRLAS increasing, email sent to experts

Guard Tours
18:48 - 19:24

After lunch it was necessary to reboot the olserverwin.virgo.infn.it Windows machine because it was not responding to ping.

At around 20:08 local time, I was called by the operator to perform the horizontal centering of SDB1 IP, which I wasn't able to complete this morning due to the issues described in entry 68141.

Another problem accurred in this attempt. The standard tool used to center the tower IP didn't find the server of the DSP crate. I've contacted Akis for assitance, and he found a temporary solution to allow the centering. He should fix completely the problem tomorrow.

After that, the IP centering was completed successfully. Operations ended at around 20:45 local time

This morning, we tried to center the IP of SDB1 tower since the Sa_OB_F0_COIL_H2 coil is close to saturation (correction voltage is above 9V). Unfortunately, we discovered a problem in the communication between the detection bench (DET) MotorUI and the motors server that prevented us to turn-on the motors and then to complete the operation. The picture attached shows the error log in the MotorUI terminal

Currently, we can't use the MotorUI to turn-on the detection bench motors but we have managed a temporary workaround to restore the connection with them; it's necessary to open the DET MotorUI through this command line: virgoDev/AdvMtrUI/v4r1/Linux-x86_64-CL7/bin/mtrLilli-conda DET

This morning, taking advantage of Matthieu and Piernicola’s presence in the Laser Laboratory, we checked the valve opening values in the ACCESS (people inside) and SCIENCE (no people inside) operating modes.
In Figure 1 is reported the behaviour of some parameters: supply (OUT) and return (IN) frequency, flux, pressure....  Below are some observations:

• when switching between the two AHU operating modes (SCIENCE and ACCESS), the supply fan frequency is manually adjusted via the Kieback & Peter control interface (acting on the inverter), while the return fan speed automatically readjusts accordingly;
• although the operating mode was set back to SCIENCE, the frequency values of supply (*FREQ_OUT*) and return (*FREQ_IN*) did not exactly match the initial ones, Figure 2;
• while the supply fan values appear to correspond well with the inverter display readings, the return fan shows a difference of approximately 2 Hz between the inverter display and the trend in the plot;
• the inverter values for the supply and return fans, as configured via the Kieback & Peter control interface, do not correspond to the values shown on the inverter displays;
• the supply and return valve openings in the different areas of the Laser Laboratory are always manually set to fixed values, as reported in the table below, for both AHU operating modes.

A value of 0% corresponds to a fully closed valve, while 100% corresponds to a fully open valve.

The attached drawings show the distribution of the supply (blue) and return (red) air ducts. The position of the valves along the ducts and in the different areas is indicated by the label RP (regolatore di portata, flow regulator).

Due to wrong configuration on iSCSI multipath on xenhost165,xenhost171 and xenhost133 these olserver has been rebooted:

• olserver225
• olserver411
• olserver412
• olserver423
• olserver424

ITF found in Science mode.

At 7:00 UTC ITF in Maintenance mode, below the list of the activities communicated in control room:

• standard tasks performed by the operator:
  • scan and lock of the OMC in single bounce;
  • TCS thermo camera images reference;
  • check of the TCS powers:

• CRAL building digging work;
• from 9:30 UTC to 10:30 UTC PSTAb realignment in the AOM (INJ team);
• SNEB microsprings and DMS warning;
• Tests of ACS INJ; for this test I set the UTA INJ in PORTATA NOMINALE from 10:13 UTC to 10:49 UTC;

All the activities completed at 11:18 UTC; I manually realigned the cavities, then the CITF and then I adjusted MICH offset. Finally the ITF was in Science mode at 12:40 UTC.

SUSP

This morning the susp on-call tried to fix the high voltage for F0 OB COIL H2; unfurtunately he discovered a bug in the software that is preventing to restore the situation. At the moment the SUSP team is trying to fix the bug and then they will be able to restore the corrections.

The control of the WI etalon was misbehaving since the 3rd of November. This could be due to a too low gain of the normal control (the one that is activated once the error signals exceed the treshold of 0.05).

We have changed the gain from 2700 to 5500

to be observed in the next days

ITF found locked in LOW_NOISE_3 with SCIENCE mode (Autoscience OFF); BNS Range ~53 Mpc.
22:27UTC - ITF unlocked due to DIFFp_TY divergence (pdf 1) and from LOCKING_OMC_DARM_B1_PD3 at 22:55UTC due to excess power on B1p.
23:46TC - ITF relocked to LN3 (with MICH_SET=40, SR_TY+=1.5urad) back in SCIENCE at 23:49UTC. BNS Range ~50 Mpc. ITF left locked

SUSP
SDB1_IP>Sa_OB_F0_COIL_H2 began to saturate at 02:30UTC (plot from DMS in fig.1)

14:00 UTC ITF in SCIENCE
16:30 UTC ITF in COMMISSIONING for ISC injections (inject_asc_test.py) (16:30-16:52)
16:52 UTC ITF in CALIBRATION for cali with ITF unlocked

1. Measurement of the TF between CAL and Sc channels, and of PCal sensing delays (16:52-17:05)
2. Measurement of actuators response for PR and BS mirrors (17:05-17:51)
3. Measurement of actuators response for NI,WI mirrors (17:52-19:12) - NE alignment (ty+2 uRAD) and MICH offset (40, 400s) added halftime during CARM_NULL timer because LN1 state achieved by READY_DF_INtoEND_LN does not include the option of stopping after the CARM_NULL timer to modify MICH offset as usual (Bersanetti)

19:25 UTC ITF in SCIENCE
22:00 UTC ITF left in SCIENCE

Guard Tours (UTC)
18:54 - 19:35
21:20 - 

The activity regarding the balancing of NI, WI and SR MAR Z actuation is concluded, because there is no margin to reduce more the coupling from Z CORR ot TY CORR by a simple adjusting of driving coefficients.

The impact of the re-balancing on the alignment stability has been evaluated, comparing recent data in moderaterly windy condition with older data in similar condition (fig 1). The spectrum of the alignment error signals correlated to the Z actuation mis-balancing is shown in the following figures. DIFFp_TY, the most important d.o.f. of the arm alignment, is shown in fig 2: there is a clear improvement below 0.1 Hz (the changes above 0.1 Hz are very likely independent on the actuation balancing). In order to understand whether the improvement is big or small in terms if ITF stability, the total rms is the quantity more appropriate to look at. In fig 3, a calibrated version of DIFFp_TY is shown, including the cumulative rms. The data refers to the first time slot, before the optimization of the balancing. We can see that the largest contribution to the alignment fluctuation comes from the frequency band above 0.1 Hz; the margin of rms reduction is about 10 %, in this environmental condition. Following this criterion, the expected improvement of the ITF alignment quality, induced by the actuation re-balancing, is small.

North arm and west arm TY SOFT d.o.f.s are shown in fig 4 and fig 5. Both are more accurate after the balancing; especially north arm. We can guess the total rms to be significantly improved as well, but this analysis is not straightforward, when the in-loop error signals are optical levers. Moreover, we use to consider the ITF quite tolerant respect to SOFT fluctuation and we never had the impression to be close to some limit, concerning the accuracy of those d.o.f.s. In conclusion, it is difficult to assign a grade to the obtained improvement.

Fig 6 shows DIFFp_TY, the last d.o.f. on which NI WI actuation balancing should have an impact. In this case no improvement is visible: the recent data are even worse. This is something to better investigate: a different noise source needs to be identified, which overcome the effect of the actuation mis-balancing.

Fig 7 shows SR_TY: the rebalancing has an effect, likely not relevant, as already discussed in a previous entry.

Finally, let's try to find the effect of the actuation balancing on the usual overall figures of merits: B1p power (fig 8 ) and sidebands power (fig 9). According the choosen data, there is no visible improvement.

This morning we compared B1p_QD1_50MHz and QD2. An offset was introduced on the QD1 signal until the other was centered in 0.

There are a couple of interesting effects:

• the coupling of RIN with DARM (LSC_DARM_PSTAB2_COUPLING) improved noticeably
• the high-frequency coupling between SSFS and DARM (DARM_SSFS_LINE) worsened noticeably

ITF found in Science mode.

ITF unlocked at 8:14 UTC because of the following earthquake: M 6.0 - 120 km E of Yamada, Japan; ITF back in Science mode at 9:27 UTC.

From 10:01 to 10:02 UTC ITF in Commissioning mode to test the BS_TX offset to zero the QD2 signal instead of QD1.

Suspensions

OB F0 coil H2 close to saturation (see plot); experts informed by mail.

SBE

SNEB F0 H2 actuator drive close to saturation (see plot); experts informed by mail

Friday, November 7, 2025 at 10:48 PM xenhost146.virgo.infn.it crashed and these machines have been rebooted on another host:

• w3.virgo.infn.it (https://scientists.virgo-gw.eu)
• pub26.virgo.infn.it (TDS, Logbook and DRS)
• pub22.virgo.infn.it (https://apps.virgo-gw.eu)
• datagw2.virgo.infn.it (data transfer machine)
• mysql1.ego-gw.it (Mysql server for TDS, logbook, drs)

All services have been restart correctly except for w3.virgo.infn.it (https://scientists.virgo-gw.eu) where we have reported some issue on mounting points side. What I did by terminal on my smartphone it turned out not to be sufficient to fix the issue reported us by email by Nicolas Arnaud.

Only today I found out a possible culprit and fixed the configuration to avoid the same behaviour on reboot.