This morning the lock was unstable, I found the ITF in locking mode and we reached quite easily the Science Mode (waiting for a lot at Low Noise 1), but the lock kept only for a few minutes. After that we collected many unlock events:

• 07:28 UTC - Science Mode -> 7:34 UTC ITF unlocked (earthquake).
• 08:08 UTC - Science Mode -> 8:31 UTC ITF unlocked (SSFS saturation).
• 09:04 UTC - Science Mode -> 9:46 UTC ITF unlocked (MICH oscillation).
• 10:29 UTC - Science Mode -> 10:32 UTC ITF unlocked (fast unlock).
• 11:42 UTC - Science Mode.

I used a few seconds of data from yesterday when no power was going through the IMC in order to check the residual electronics offsets in the B1p and B5 quadrants H, V and Sum signals (see Fig.1). According to the quadrant Vbias channels, the Vbias was ON at that time (although the very low sampling rate of this channel - 0.01Hz does not allow to check this precisely).

The measured residual offsets are listed below:

• B1p_QD1: H = 1.25e-3 V, V = -0.26e-3 V, Sum = -0.24e-3 V
• B1p_QD2: H = 0.16e-3 V, V = 0.18e-3 V, Sum = -0.18e-3 V
• B5_QD1: H = 0.024e-3 V, V = -0.25e-3 V, Sum = -0.60e-3 V
• B5_QD2: H = 0.04e-3 V, V = 0.08 e-3 V, Sum = -0.075 e-3 V

These values are negligible compared to the offsets which are corrected in the configuration file (which are of the order of 0.01-0.1 V).

The instability seems back, but at a different frequency: 263Hz. this happens after yesterday maintenance, actually since the lock of 13:30 UTC (Figure 1)

The line is very strong  in SSFS but also PMC TRA (Figure 2): where there are extra lines starting from 12.7Hz

Yesterday morning mitigation intervention on the noisy cooling fan of the PR-BS pump driver removed the 392Hz line  from the environmental seismic and acoustic sensors and from Hrec. Apparently no new peak appeared in the env sensors or in Hrec. To be monitored.

ITF found in relocking State, LOW_NOISE_3_SQZ reached at the first attempt. Science Mode started at 13:32 UTC.
At 13:47 UTC UTC I set to Adjusting mode to switch to Earthquake configuration ( Earthquake M 6.4 - 33km WSW of Tsuruoka, Japan, 13:22 UTC, see attached image #1 ), but even with this configuration the ITF unlocked at 14:09 UTC.
ITF back at LOW_NOISE_3_SQZ at 15:42 UTC, but there was an excess of noise in the sensitivity curve. Triggered by a red flag I contacted the SQZ Oncall ( M. Vardaro ) that verified that the Squeezing was working correctly. A. Allocca tried to improve the working point of the ITF ( from around 16:00 UTC to 16:45 UTC, activity agreed with the Run Coordinator, see entry logbook #46147 ), back in Science Mode at 16:49 UTC.
The ITF unlocked twice after the adjustment ( 17:32 UTC and 20:03 UTC, see attached plot #2 and #3 ), in both cases there were no issue to recover the lock.
Science Mode from 20:34 UTC, ITF left locked.

TROUBLESHOOTING
Troubleshooting mode set from 15:53 UTC to 16:49 UTC due to the excess of noise in the sensitivity curve. The flag brms_LSC_DARM_20_2_2600_2800, under SQZ_Inj, reported that the Squeezer was injecting noise in the ITF. The SQZ expert verified that the issue was not related to the Squeezing. Troubleshooting period extended to allow A. Allocca to improve the Working point of the ITF. SQZ_Inj flag still red.

ENV
The flag delta_ENV_CEB__DUST_0P3UM_3600 became red since 11:21 UTC, reporting that the CEB particle counter is not working correctly. I tried to reach via web the related counter, but the connection was refused.

VPM
At around 16:30 UTC the DMS reported that the process CaliMoni wasn't working anymore. Checking on the VPM I found out that TFMoni stopped responding ( process red on VPM ). I tried to restart it but the process was still alive on its host (olserver52). I manually stopped it I was able to start it again at 16:33 UTC.

Guard Tour
17:32 UTC - 18:04 UTC
19:35 UTC - 20:02 UTC

After the relock, we noticed an excess of frequency noise in Hrec (the usual step after 3.5kHz).

We tried to optimize the alignment working point in order to reduce it, but unfortunately this action didn't seem to have any effect on it.

We changed:

• DIFFp_TX from -0.02 to -0.04
• BS_TX from 0.003 to 0.0005
• BS_TY from 0.002 to 0.0005
• PR_TX from 0.007 to 0.009

Although these offsets seemed to improving the sidebands and reduce the fringe, they were not saved in the ITF_LOCKini file, because the transition from DC READOUT to LN3 was not tested, and being some of the offsets significantly different, we would risk to unlock in the transition.

Maybe replacing these offsets would need a dedicated commissioning time.

Still no effect on the high frequency step.

05:00 UTC, ITF found in Science Mode with BNS Range 46 Mpc.
05:20 UTC, Calibration Mode set.
05:20 UTC, Magnetic Injections. Procedure manually interrupted at 06:09 UTC.
06:09 UTC, Maintenance Mode set.
06:10 UTC, Longitudinal Noise Injections launched by me.
06:25 UTC, I restored the communication with Power Supply Hameg 17 at NE. SNEB_PowerUnit17_Picomotors_p12v_volt again available.

Maintenance activities communicated to the Control Room:
06:30 - 11:00 UTC, Extraordinary intervention on WEB HVAC system by Soldani with the external company. (ACS_WE red flags on DMS, thresholds to be tuned)
06:10 - 09:00 UTC, Nitrogen refill by Linde company and Vacuum team.
06:40 - 09:30 UTC, PR-BS and WI-BS leak test with valves closed by Vacuum Team.
06:10 - 10:00 UTC, Cleaning Operations by Ciardelli and external company.
06:10 - 10:00 UTC, Grass cutting by the external company near CB.
06:30 UTC, TCS Chiller check; refill on WI chiller (Ciardelli).
06:10 - 09:00 UTC, tiltometer intervention at NE by E. Calloni.
07:30 - 09:00 UTC, CB_HALL Particle Counter replaced with a spare one (Ciardelli), old probe not working properly. ParticleCounterCEB process stopped, parcount4 reconfigured/saved, ParticleCounterCEB restarted, FbsMoni reloaded. TBC the data.
09:07 UTC,  Ing team at NE to turned ON PcalNE.
08:00 UTC Beam Pointing Control corrections reduction by Inj crew.
09:50 UTC, Measurement of CARM2MC OLTF by J. Casanueva
11:03 UTC Stop Maintenance Mode
Relocking in progress. Few unsuccessfully attempts.

This morning during the maintenance I re-measured the OLTF of the mechanical loop of the MC when using the error signal coming from the arms. The delay is still there (see entry 46076). The origin is not understood.

This night, two times the Sc_NI data were not received during 7s

• From GPS1244858956 to  GPS1244858963
• From GPS1244866884 to  GPS1244866891

Here the report oft the SUSP_Fb server :

2019-06-18-02h08m59-UTC>WARNING-[TolmFrameBuilder::TryMerging] frame: 1244858955.000000000: merging is done on timeout
2019-06-18-02h08m59-UTC>WARNING-[TolmFrameBuilderSourceManager::MergeSubFrames] Source Sc_NI: 9260/10000 missing packet(s), 1 data break(s)
2019-06-18-02h08m59-UTC>INFO...-[TolmFrameBuilderSourceManager::Clean] Source Sc_NI (version 7) stopped
2019-06-18-02h08m59-UTC>INFO...-[TolmFrameBuilderSourceManager::PrintLog] Missing source(s): Sc_NI - Unexpected source(s): none - Source with all data lost: LSCToSUSP, DAQ_DEMOD_TIMING_1
2019-06-18-02h09m00-UTC>INFO...-CfgReachState> Active(Active) Ok
2019-06-18-02h09m05-UTC>INFO...-[TolmFrameBuilderSource::SetUp] new source Sc_NI (v7) at (corrected) GPS time: 1244858963.307212020
2019-06-18-02h09m05-UTC>INFO...-[TolmFrameBuilderSourceManager::PrintLog] Missing source(s): none - Unexpected source(s): none - Source with all data lost: Sc_NI
2019-06-18-02h09m06-UTC>WARNING-[TolmFrameBuilderSourceManager::MergeSubFrames] Source Sc_NI: 3072/10000 missing packet(s), 1 data break(s)
2019-06-18-02h09m06-UTC>INFO...-CfgReachState> Golden(Golden) Ok
2019-06-18-04h21m07-UTC>WARNING-[TolmFrameBuilder::TryMerging] frame: 1244866883.000000000: merging is done on timeout
2019-06-18-04h21m07-UTC>WARNING-[TolmFrameBuilderSourceManager::MergeSubFrames] Source Sc_NI: 8024/10000 missing packet(s), 1 data break(s)
2019-06-18-04h21m07-UTC>INFO...-[TolmFrameBuilderSourceManager::Clean] Source Sc_NI (version 7) stopped
2019-06-18-04h21m07-UTC>INFO...-[TolmFrameBuilderSourceManager::PrintLog] Missing source(s): Sc_NI - Unexpected source(s): none - Source with all data lost: LSCToSUSP, DAQ_DEMOD_TIMING_1
2019-06-18-04h21m08-UTC>INFO...-CfgReachState> Active(Active) Ok
2019-06-18-04h21m13-UTC>INFO...-[TolmFrameBuilderSource::SetUp] new source Sc_NI (v7) at (corrected) GPS time: 1244866891.279055720
2019-06-18-04h21m13-UTC>INFO...-[TolmFrameBuilderSourceManager::PrintLog] Missing source(s): none - Unexpected source(s): none - Source with all data lost: Sc_NI
2019-06-18-04h21m14-UTC>WARNING-[TolmFrameBuilderSourceManager::MergeSubFrames] Source Sc_NI: 2790/10000 missing packet(s), 1 data break(s)
2019-06-18-04h21m14-UTC>INFO...-CfgReachState> Golden(Golden) Ok

This morning we removed the cooling fan of the driver of the PR-link turbo-molecular pump, with the aim to reduce its acoustic/seismic emissions  [see logentry_46103] . The new cooling fan (an ordinary model) has been mechanically detached from the metallic box of the driver. The driver is protected by an overtemp switch.

Effects to be checked at next relock.

Reconfigured the SQZ_DBOX_2 DBOX  to reset it timimg_error .

Stop/Restart the  SQZ_CC_Ctrl server

This morning we replaced the old antenna for lightning detection with a new one. The probe   functionality has been checked (see fig. during a "fake" signal produced with a mobile phone close to the antenna...) and it seems ok. The server is still working and the data are available (ENV_Zeus_....). At the same time we mounted and checked the new electric field probe (also placed on the control building roof). The data from this probe are not available yet, since the full connection is not possible at moment. It will be done in next days.

On June 14th we were informed by the operator that NE photon calibrator was down since June 13th around 23h30 UTC, and could not be turned on again on VPM.
This morning, we asked Gabriel Pillant on site to check the status of the laser driver directly in NE building. The pump was disabled and no alarm/warning were displayed on the driver.
I asked him to disable the remote control and enable the pump manually. It worked. So we get back in remote control and I was able to turn on the laser from VPM.
NE photon calibrator is thus back on since 09h05 UTC this morning but we do not know exactly what happened on June 13th and we still need to investigate this problem.
Thanks Gabriel !

During the maintenance of this morning, I reduced the correction of the BPC (attached plot)

ITF found in Science Mode. The lock survived an Earthquake (M 5.9 - 19km SSE of Changning, China, 14:55 UTC, see attached image #1 ), during this period the ITF was kept in Science Mode, no Earthquake configuration needed.
ITF unlocked at 20:20 UTC ( see attached plot #2 ), relocked at first attempt, back in Science Mode from 20:57 UTC.

ISC
Since the relock at 12:45 UTC the DMS flag ViolinModes became red, reporting that the modes are excited ( see attached plot #3 ).

Guard Tour
17:32 UTC - 18:04 UTC
19:44 UTC - 20:22 UTC

I increased the LSC_WArm_GAIN from -350 to -1000 in order to supperess the 14 Hz oscillation. This gain was increased online but I did not save it in the metatron ini file. At the next relock the oscillation was naturally damped.

Upon arrival, I found ITF in Science Mode with BNS_Range ~ 45 Mpc.
ITF very unstable, It unlocked several times: 05:07, 05:53, 06:50, 08:52 UTC.
Mantovani and Ruggi are looking at the signals and analyzing this instability.

13:00 UTC - ITF left in Science Mode. BNS Range ~44 Mpc.

Susp
After the unlock of 08:52 WI LC opened by the guardian. With L. Trozzo (present in Control Room) we tried to close them without success due to an excess of oscillation at the level of F7. Lucia asked Majorana to fix the problem.
ISC
Upon closed WI loops, an oscillation at 14 Hz was still present on B8_DC. ISC expert damped it increasing the W arm gain loop by a factor 3 (from -350 to -1000).

VPM - DetChar
06:01 UTC lvalert_virgo crashed. Properly restarted at 06:02 UTC.
VPM - DataAccess
08:44 UTC MdVimSpectro crashed. Properly restarted at 08:57 UTC.
11:00 UTC MdVimSpectro crashed. Properly restarted at 11:04 UTC.
VPM - Storage-Stole03
09:00 UTC FbTrend10800 crashed. Properly restarted at 09:01 UTC.

CalibHrec
PCalNE (TFMoni_NEPCAL_PD1_PD2_60_Cohe) red flag on DMS, since 14/6 (plot). Expert informed.

Cali
11:00 UTC MagneticInjections launched under request of Paoletti.

ENV
Meteo station repaired (De Rosa).

Vacuum
12:44 UTC - VAC_TUBE3000N..V21ST again in operation thanks to Macchia

The meteo station is now working again. The switch off of last 9 June was due to a failure of the power supply. It was substituted and the data are now back.

A possible explanation of SSFS instability at 274.8 Hz is the presence of a spurious crossing between the mechanical loop on MC mirror (low frequency) and the loop on the laser frequency (high frequency), perhaps due to a high Q resonance of MC payload. This morning a narrow notch to MC loop has been added. Let's see if it works.