For checking that the frequency points at the swept sine of calibration measurements are contaminated by spectral peaks, I made a latest ASD with fine (~mHz) resolution.
Then I found that 4.17Hz and 9.77Hz combs came back which were seen also on OMC dark and CARM error signal, respectively as shown in Fig.1 and Fig.2.

These two plots were made with the data around 15:00 JST and 23:00 JST on Nov. 6th. Former and latter locks can be seen in Fig.3 as t = 6h-11h and t = 14h-20.5h, respectively. The lock duration of these two were ~5hr and ~6.5hr and there was no human activities in order to check the stability with disabling the whitening filter stage for the DCPD (probably for former lock and surely for latter lock in my memory).

These two combs were loud during O4a and were mitigated before before O4c (Comparison around 100Hz would be the easiest to understand). I couldn't remember how to mitigate the 4.17Hz combs on OMC (pin assignment of ZSW, cabling route around AS table, or else?). Though there was possibility that noise itself became louder than before, disabling the whitening filter makes SNR of these series peaks louder. If so, there may be no way to suppress them for now because stable IFO is unavailable with engaging whitening filter. In my memory about 9.77Hz combs on CARM, they were able to mitigated by adjusting the input gain of CMS as positive. Though I was not able to track recent activities about replacing IMC-CMS precisely, now the original common mode servo chassis were used for IMC and input gain were set as positive. So I have no idea why 9.77Hz combs came back. replacing chassis and/or re-cabling changed some situation around electrical connections...?

I checked the OMC DC PD signals in each lock from last night.

Figure 1 shows the OMC DC PD signals at the lock from 2025/11/6 06:03:48 UTC.
Since the speed of glitches is very fast, the signals would be enhanced by a factor of 10 if the whitening filter is off.
So, if the glitch reached around upper Y-cursor, the signals would be saturated if the whitening filter is on.
There are four glitches that exceeds the upper Y cursor, so the lockloss should be happened if the whitening filter was turned on.

Figure 2 shows the enlarged view of one glitch in fig1.
Clear ring down can be seen, so it seems due to the kick of suspensions.

For the lock from 2025/11/6 11:41:06 UTC, these is no large glitch that exceeds the threshold.
For the lock from 2025/11/6 12:22:33 UTC, these is also no large glitch that exceeds the threshold but the glitches close to te threshld can be seen as shown in fig3.

For the lock from 2025/11/6 13:55:08 UTC, there is 2 glitches that exceed the thresold.
One of them is smilar glitch as shown in fig2 but the other is different: very short glitch calmed down within 1 second (fig4).
The similar short glitch can be seen in the lock from 2025/11/6 21:48:58 UTC, which seems very clear sine gaussian noise (fig5).

So, some DC PD saturation seemed suspension kick but there might be another reason of sudden glitch in OMC DC PD.

Operator: YokozaWashimi
Shift time: 9:00-17:00 JST

Check Items:
VAC: No issues were found.
CRY temp: No issues were found.
CRY cooling water: No issues were found.
Temp: No issues were found.
VIS GAS filter: No issues were found.

IFO state(JST):
9:00 : STANDBY
17:00 : CALIB NOT READY

This is a report of last week. Sorry for late.

As reported in klog34823, the gap of the frame data in Kashiwa cluster (called system-B) was filled on 10/10. So, I regenerated the segment files of 8/13 data, via k1det2.
The working directory is /users/yuzu/work/20251030_segment@k1det1. I used the conda environment of igwn-py38, which is same environment as the regular segment production.
I asked the final review of the generated segment files to YamaT-san. After his confirmation, I will copy the files to the /users/DET/Segments and ask the upload of segment files to DQSEGDB.

NOTE

• To reproduce the segment files reading 1 day data, it took around 30 minutes.
• After the trouble of the missing frame data, I just suspended the copy process from the temporal directory to /users/DET/Segments. So, the other segment files (after 8/13) are regularly generated and stored in /users/DET/tools/Segments/Script/Partial.
• From August 15 (in UTC timezone), the interferometer was unfortunately not in the OBSERVATION state due to the laser issue (klog34839 and klog34840). So, we don't need to care the segment files after August 15.

Abstract:

It doesn't seem easy to improve the MICH and PRCL FF performance by changing the gain.
So, I keep current setting for them.

Detail:

I measured the Tf from MICH OUT to DARM to optimize MICH FF gain.
Figure 1 shows the measured TF with various condition.

Blue line shows the reference, which was optimized just before joining O4c.
Green line shows the current TF before optimization.

To improve the MICH FF performance, a gain of 1.11 is better than the gain of 1 (compared with brown and pink line in fig1).
However, even though changing the MICH FF gain to 1.11, overall performance (after engaging PRCL FF at the same time) of MICH FF becomes worse (compared with green and cyan lines).
I also tried to optimize MICH2PRCL FF and PRCL2DARM FF but it is hard to find the good configuration with a short term.

So, I keep FF setting as it was.

I accepted Pcal beam position related SDF diffs as reported klog35522.

k1calex

k1caley

A CAL Tcam session was performed to obtain beam position information necessary for Pcal. The parameters have already been updated, and SDF has been accepted.

Operator: Dan Chen

Update Time: 2025/11/07 11:27:28

Update Time: 2025/11/07 11:28:31

Update Time: 2025/11/07 11:29:07

Update Time: 2025/11/07 11:29:38

I accepted the following SDFs.

k1asc1 (fig1):

These changes were done for IFO stability check on November 6.
Since TRAMP doesn't affect to the IFO condition, I accepted them.

k1lsc (fig2):

All changes are related to the work reported in klog35505.
Since they should not affect the IFO condition, they are accepted.

k1omc (fig3):

All changes are related to the work reported in klog35510.
Since these changes are for improving the stability of IFO,  they should be accepted.

k1visetmxp (fig4):

All changes are related to the work reported in klog35510.
Since they should not affect the IFO condition, they are accepted.

k1ascbpc (fig5):

This change is related to the work reported in klog35504.
Since this change is for keeping beam spot on ETMY at the center, it should be accepted.

The followings are the memo related with cleaning (2009Feb02).

--- Cleaning ---
We performed cleaning inside the Mephisto2000NE.
Result: Power increased from 800mW (2.3A) to 2W (2.3A).

--- Why does the interior get so dirty? ---
First, the booth cleanliness is ound Class 300, which should be acceptable. The HEPA filter operates at AC60V.

According to Mr. Nishibata (Indeco Inc at that time):
1) Lasers used by customers for applications heavily utilizing PZT tend to get dirty quickly elsewhere too. On the other hand, those not using PZT show slower fouling.
2) The crystal surface facing the PZT wiring is overwhelmingly dirty. In other words, it's likely that vibrating the PZT causes dust to be ejected from the wiring and adhere to the crystal surface. Since this is an internal structural issue, I requested that it be addressed in the new laser currently under production. For the current laser, covering the PZT wiring with Kapton tape might help, but we haven't done that yet. 

I took the TCam photos for commissioning at 08:43 ~ 08:50 this morning. The previous work is klog35448. We don't need to update the reference positions.

So, so stable IM temperatures for IY and EX, while EY is increasing.

Since the temperatures in the corner station appear to be decreasing, I increased the target temperature of the SR-C precision cooler from 18.00 to 20.00 around 6:30.

I slightly adjusted currents for EX/IY (Fig.1, 2) IMs around 0:00 and 6:00 today. If the suspension kicking rate will not change, we should consider other reasons, except for the temperature changes in the cryostat area.

I increased the current for IY IM to realize the constant condition around ~40K. The temp of EX IM seemed to be around 40K.

I increased the current for EX IM to realize the constant condition around ~40K.

Because the temperature in IXV decreased and F0 GAS position is also decreasing, i increased the Delongh heater power from 600W to 900W around 18:30.

F2 is also decreasing.

To check if the reason of OMC DC PD saturation is the suspension kick, I locked PRFPMI without engaging whitening filter for OMC DC PDs.
It degrades the ADC noise and noise floor got slightly worse, ADC range at high frequency increases by a factor of 10.
So, if the large suspension kick is the reason of the lockloss, it would help t keep the lock.
To keep this configuration, I modified the OMC_LSC guardian as shown in fig1.

Operator: YokozaWashimi
Shift time: 9:00-17:00 JST

Check Items:
VAC: No issues were found.
CRY temp: No issues were found.
CRY cooling water: No issues were found.
Temp: No issues were found.
VIS GAS filter: No issues were found.

IFO state(JST):
9:00 : LOCKING
17:00 : LOCKED

I increased the current for EX IM.