Upon arrival I found ITF just relocked and in Science Mode.
Unlocks:
- 23:19 UTC (?). Relocked at first attempt. 
- 01:32 UTC probably due to the seismic activity in Taiwan. Relockeed at second attempt at 03:36 UTC. 

Guard Tour (UTC)
21:06 - 21:34
23:08 - 23:34
01:04 - 01:30
03:15 - 03:45
 

https://gracedb.ligo.org/superevents/S240422ed/view/

Today the lock acquisition was very troublesome due an excess of noise on the West Green beam. We tried to check the coupling of the fibers on the DAQ room, but it didn't solve the problem. Then we went to the end building and tried to improve the fiber coupling by moving the fibers in the rack. We found a position where the noise was reduced. Still there is some green power missing, so tomorrow some more systematic alignment work will be done, in order to better align the green in the SHG box. After this action the lock acquisition worked properly.

Today, I found ITF unlocked with WI and WE guardian opened. I closed the guardian on both and realigned the mirrors to have back the flashes on B8, P. Ruggi used the dumper on WI Y to reduce the excitations of the mirror after the opening of the controls. I then aligned the CITF and restarted the locking acquisition. 15:30-15:40 UTC The WE guardian opened again. I properly closed and restored the position of the WE mirror that went off. M. Boldrini, J. Casanueva, D. Bersanetti, and M. Was are working on the ITF recovery. We discovered some problems, the first one was an issue with the WE ALS green (fixed by J. Casanueva and M. Boldrini with C. De Rossi from remote), second problem was with Ch e Das WI by mistake a flipper was left closed, I re-opened at 19:05UTC with the guidance of I. Nardecchia and the third problem was on PR_TX gain adjustments (D. Bersanetti and M. Boldrini). We had an 18:26 UTC earthquake in 6.3 Taiwan and an 18:32 UTC earthquake in 6.4 Taiwan. 20:50 UTC ITF back in SCIENCE. 

Yesterday's situation has been restored: PR_TX is reset to 2.2 in CARM_NULL_1F and is set to 2.2 as well in LOW_NOISE_1.

The gain change in LOW_NOISE_1 is kept in Metatron's code, but is currently doing nothing.

Around 19:00 LT, I discovered that the WI flip mirror used to acquire the thermal camera images was closed. This means that the CH and DAS were blocked on the bench since last night.

Gianmatteo re-opened it at 19.05 UTC.

A few of today's unlocks, after the wind settled down, have been caused by low gain oscillation for PR_TX (Fig.1).

Increasing the gain in CARM_NULL_1F caused an unlock soon after the transition, so we introduced a gain change in ACQUIRE_LOW_NOISE_1 (line 5232 and 5275 in ITF_LOCK.py).

The modifications can easily be reverted or made transparent (by simply setting this gain to the same value in CARM_NULL_1F and LOW_NOISE_1) if need be.

6:00 UTC: ITF found in BAD_WEATHER due to high wind and sea activity.

At 10:13 UTC I removed the mode BAD_WEATHER because the related flags WIND and SEA on the DMS were not red anymore but unfurtunately the lock acquisition continued to fail at various state; Maddalena checked from the control room.

After a check we discovered a change in the WI CH power that happend last night thus, at 10:30 UTC, I set TROUBLESHOOTING and we contacted Ilaria to restore the good value of the powers. This problem was not reported on the DMS thus a readjustment of the thresholds is needed.

After this change the interferometer continued to unlock also due to a further worsening of the weather conditions: strong storm with lightning and thunder.

The commissioning team present in control room is investigating at the problems.

ALS

As reported in the previous shift the DMS is reporting a problem with WE ALS Laser; this morning I informed the experts by mail. At 12:00 UTC I did not receive any answer thus we decided to contact the ALS on-call; unfurtunately he is not available to look at the problem.

SUSP

At around 12:50 UTC WE and WI LC were opened by the guardian after an unlock. I tried to close the loops but the new GUI interface did not work; for this reason I contacted the SUSP on-call. Investigation on the problem in progress from control room.

These events are likely correlated  to the burst of jobs that have been automatically submitted to the HTCondor farm by the DQR and detchar pipelines some time before, triggered by several H1 GstLAL alerts.

Between 4:20 UTC and 6:20 UTC about 1600 of these jobs have run causing a peak of more than 150MB/s nfs read traffic and consequent overload  of the fs01 fileserver where /virgoLog is hosted.

Since RTPCs still mount /virgo, /virgoApp and /cvmfs via NFS from fs01 instead of CVMFS, they may have been impacted by the corresponding slowdown which however has not provoked any visible errors at the Operating System level.

The altitude was also very low at the closest point (400ft --> 120mt).

Sometimes we can find data with BNS range stable above 56 Mpc for several minutes. This is the best level we can reach since several weeks. In march we had something better: for instance, on March 8th the range was 58.9 Mpc, averaged over 10 min.

In order to understand where those 2 Mpc have been lost, the two sensitivities are compared in fig 1. In order to understand better, the two cumulative BNS ranges have been computed and subtracted (fig 2).

It is clear enough that the mystery noise is not involved: a change of its level should be well visible in the region 80 - 120 Hz, where instead the sensitivity is equal. The bigger drop is below 80 Hz, both because an increase of the broadband noise and the presence of new structures. If we want to reach the psychological threshold of 60 Mpc, this region needs to be better studied.

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

On-call events -> Air Conditioning

Title: water leak in COB officies conditioning pipe

Author(s): soldani

Details:

At the request of the In shift-Operator A.Magazzu', I reached the site to stop the water leak from the air conditioning pipe for the offices on the ground floor of the COB.
The relevant shutters were closed and the company in charge of maintenance was contacted, which this morning (22/04) is already working to replace the affected section of pipe (whose installation dates back to 1996) because its state of conservation does not allow a repair that gives a guarantee of reliability over time.
If there are no unforeseen events, the restoration work will be completed the same day.

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

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

On-call events -> Injection System

Title: pmc pzt corrections high

Author(s): derossi

Details:

I was called by the operator because the flag PMC PZT was red.
We had set the flag red when the PMC PZT corrections become larger than 4,5V because in this conditions the lock would probably not last more than a few hours and it could be worth to manually unlock the PMC to reset the corrections (during the lock the corrections are likely to increase until 7V, causing the PMC unlock). Since is not something which prevents the ITF to lock we changed the color of the flag in the DMS: yellow from 4,5V to 6,5 and red starting from 6.5V.

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

Upon arrival I found ITF relocking after the earthquake.
Relocking in progress but ITF very noisy due to the high wind and sea activity increasing (plot3). The bad weather conditions prevent a stable lock for the whole shift.

ALS
I noticed that after the intervention at WE on ALS laser amplifier, the Green Power and the IR_PSTAB are not in a good working point (plot2).

SBE
After one of the unlock events SNEB Horizontal loop opened. Properly closed.

TCS
During a relock the CH TCS_CO2..REL3 got stuck at 1. I act ON Up via TTL_CO2.

Guard Tour (UTC)
21:06 - 21:34
22:55 - 23:25
01:04 - 01:50
03:07 - 03:39 

ISYS
(22-04-2024 04:00 - ) From remote
Status: On-going
Description: PSL_PMC_PZT out of range (plot1). Normally after an unlock it resets but not this night (?)
DMS comment: PMC_PZT_likely_to_drift_away.

Today, I found ITF in SCIENCE. 18.30 - 18:42 UTC I started the scheduled DF_DAILY calibration. 18:43 UTC ITF back in SCIENCE. 20:11 UTC An earthquake (5.5 Mexico) caused ITF to unlock. I realigned the CITF and restarted the locking acquisition. 20:59 UTC ITF unlocked at LOW_NOISE_2.

Other
VPM
18:43 UTC restarted CALI after a crash

" So probably the helicopter respected the NOTAM. "

I guess not

Nice idea. However the original restrictions - still enforced, as reported in the attached text of the forbidden areas of the latest release of the AIP publication (https://www.enav.it/servizi-online) - are cylinders of 2000 ft = 610 m of height but radius of 0.3 nautical miles = 1823 ft = 556 m. So probably the helicopter respected the NOTAM. 

Tonight a strong and clean PC_1 magnetic pulsation was received in both the underground magnetometers of Sos Enattos and the external magnetometer of Virgo.

Here its "sound" when accelerated and shifted in frequency 100 times.

 (credits: Renato Romero www.vlf.it)

This is a first (preliminary) look at the effect of acoustic injection into Hrec, performed on Thursday 18.

For each injection (at the 0.03, 0.04 and 0.05 V levels) the BNS range decreased.

Here the entire Hrec range from 10 to 1000 Hz.

There are regions growing at low frequency (around 120 and 170 Hz) and high frequency (the most relevant from 500 to 540 Hz).

Below 100 Hz nothing seems to have changed significantly.

ITF in Science mode for all the shift.

Guard tours (time in UTC)

From 6:00 to 6:30; from 8:00 to 8:30; from 10:00 to 10:30; from 12:00 to 12:30.

Upon reaching the site, I found the ITF locked in LOW_NOISE_3_SQZ and in Science Mode. At 22:12 UTC the Squeezing disengaged, bringing the ITF back in LOW_NOISE_3. ITF back in LOW_NOISE_3_SQZ from 22:14 UTC.
ITF left locked.

Guard Tour (UTC):
21:30 - 22:00
23:30 - 00:00
1:38 - 2:07
3:07 - 3:18

DAQ
The process ELE_QGBT was not working correctly, it was reported as not working on DMS and in Orange state on VPM. At 4:13 UTC I restarted the process to solve the issue.

Upon arrival I found ITF stable locked at LN3_SQZ (Science Mode).

17:09 UTC unlock for unknown reason (TBC).
18:19 UTC relock after the usual cross-alignment in ACQUIRE_DRMI.
18:30 / 19:02 UTC - CALIBRATED_DF_PCAL.
19:02 UTC -  Science Mode set.

NO DMS Events Monitor to report

Guard Tour (UTC)
13:58 - 14:33
15:54 - 16:29
17:50 - 18:22
19:25 - 19:55

This site Elian suggested: https://www.flightradar24.com/ keeps records of aircrafts tracks.  Specifically, this is the helicopter that was flying near us on April 18 and 19: https://www.flightradar24.com/data/aircraft/mm82053.  Position and time are provided,  so is possible to locate its position at a particular time. Data are kept for 7 days. In particular its track of April 18 afternoon (attached shapshots) maybe passed a bit closer than 2000ft from CEB and NEB.

Yesterday some interesting data in windy condition has been acquired. It is useful to analyse those data because the IT was in a good state just before the wind, then there was a reduction of range during the windy condition, then the wind calmed down and the range recovered a higher level (fig 1). Everything happenend during the same lock, while other relevant parameter were reasonaby stable: this is the perfect condition to deduce what is the effect of the wind and what needs to be improved in order to keep the same sensitivity.

In windy condition, a clear worsening of the CMRF is visible. The optical gain has a small drop, but this seems not so relevant and not totally correlated to the wind speed (fig 1).

A comparison of hrec in the two conditions (fig 2) says that the additional noise caused by the wind is not simply a worsening of the mystery noise: there is for sure some flatter component visible up to 250 Hz, which could be better explained as frequency noise (the noise budget needs to be checked).

The working point, as it can be seen in the relevant ITF powers, seems not affected that much (fig 3). Only B1p is a bit disturbed, but this is more clear looking at the spectrum (fig 4).

There are a lot of suspension, alignment and correction signals disturbed by the wind: a small set of signals is shown from fig 5 to fig 8, both in time domain and frequency domain. Concerning the effect on alignment, we can just say that yaw seems more disturbed than pitch. This is reasonably correlated to the fact that the first effect of he wind is an increased horizontal motion of the suspension, because the wind creates environmental tilt at low frequency (< 0.1 Hz) and disturbes the accelerometers, involved in the suspension horizontal control. The low frequency horizontal motion can disturb the yaw control in three ways:

1) the correction on the marionettes needed to compensate the slow horizontal motion can make yaw noise because of not perfect balancing of the actuation;

2) the horizontal motion can be coupled to the local sensors of yaw dofs, some of which are in loop also in science mode.

3) the horizontal motion of some optics (PR, SR, benches) can generate horizontal tilt of the beams.

Pitch dofs are generally affected by seismic noise and suspension motion, but more in the region of the suspension resonances (> 0.2 Hz), where pendulm modes are naturally coupled to pitch motion. Microseism due to sea waves, more than wind, is the main offender for pitch motion.

Going back to the possible source of range degradation, the guess that it could be due to an unstable CMRF indicates BS_TY as a possible cause. We know that this is the angular dof better coupled to CMRF: in fact we change its set point in order to put at zero the CMRF mean value.

From fig 9 one can see that there is a strong linear correlation between BT TY and CMRF fluctuations. There is also a certain correlation between BS MAR Z and TY correction (10), which means that some angular disturbance could come from MAR longitudinal actuation and it can be reduced by a better balancing of the actuation. The transfer function between the two channels (fig 11) is 1*10^-4, which is quite a small number: the coefficient in use for the balancing arrives to the fourth digit and it seems that the last one needs to be corrected by just one unit. We can do it and see what happens, but adding the fifth digit to be more precise probably is not really possible in a stable way.

Other improvements that can be tryed are:

1) increasing the loop gain at low frequency;

2) changing the balancing in the blending strategy between quadrant signal and optical lever.

We cannot even exclude that the excess BS TY motion is driven by other optical disturbances in the ITF, affecting in the end the quadrant  used for AA control. Some commissioning activity is required, to be done step by step.

Today, I found ITF in SCIENCE. 06:06 UTC ITF unlocked (probably caused by missing data, see attachment). I called the ALS on call A. van de Walle, to restart the WE ALS laser, He will contact C. De Rossi to come on-site to do it. 09:30 UTC C. De Rossi replaced the head of the WE green laser and SOA driver. I religned the CITF at 9:45 UTC and 10.32 UTC ITF back in SCIENCE.

No DMS events

On-line Computing & Storage
Missing data 06:06:27-06:06:38 UTC and 06:16:29-06:16:41 UTC

Other
(20-04-2024 07:45 - 20-04-2024 10:10) On site
Status: Ended
Description: WE ASL laser off
Actions undertaken: C. De Rossi replaced SOA Driver and the head of the WE ALS laser

I have refined the analysis in the main entry to include more glitches and all the auxiliary channels measuring positions, velocities and accelerations, as described in this git issue. The results are contained in the attached text files. These confirm and expand what is already presented in the main entry, that is, a strong correlation of these glitches with the movement of the West End bench and suspension. Correlations with velocity and acceleration sensors are instead much smaller. They tend to point to the motion of parts of the North End building, but plotting the predictor frequencies superimposed to the spectrogram of Hrec shows in fact no convincing correlations. Example in figure 1.