Sheila, Tony, Camilla

Sheila and Tony noticed that we had a ~30 minute 10MPc range drop last night with related extra low-freq glitches, from the range BLRMs this is most clear in th 20-34Hz band. This noise is broadband 15-100Hz  looking at DARM, plot. And trending the common range drop channels form last year, plot, we see a slight increase in FC2_M3_NOISEMON, plot, confirmed as the cause by the dtt spectrum. Sheila is proposes the cause could be FC backscatter into the IFO. There is no increase in FC1 noise apart from small regions at 80Hz, 160Hz, 190Hz, plot.

There is slighly more noise 8-20Hz in HAM8 in the low range time and 3 peaks at 7-9Hz are gone, plot.

Wed Aug 27 10:09:46 2025 INFO: Fill completed in 9min 43secs

Joe B, Elenna

Since the ETMX ESD bias was changed, kappa TST has been trending upwards. This could be due to charging. Kappa TST has increased nearly 3%.

The following packages were added to the default CDS Conda environment on workstations.

- hws (Hartmann Wavefront Sensor)

- epics-striptool

- mypy, a linter and type checker for python programs

TITLE: 08/27 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 150Mpc
OUTGOING OPERATOR: Oli
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 6mph Gusts, 4mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.08 μm/s
QUICK SUMMARY:
H1 Has been Locked in Nominal Low Noise for 17.5 + hours.
All Sub Systems seem to be running well.

 

TITLE: 08/27 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 153Mpc
INCOMING OPERATOR: Oli
SHIFT SUMMARY:

IFO is in NLN and OBSERVING as of 21:14 UTC

We were locked for the entire shift. I had a chance to test out Jim and Elenna's new EQ survival ASC gain in which ASC gain is ramped when we are threatened by EQ-related lockloss. I manually turned it on when a 6.0 EQ came in from Eastern Russia upon activation of EQ mode (auto) and at least in this instance, we managed to stay locked.

Nothing else of note

LOG:

None

This logpost is a follow up to the executive summary on PR3 OSEM estimator Filter and Blend design [LHO: 86563]

Oli took the measurements needed to commission the PR3 OSEM estimator in P and Y [see LHO: 86459]. The P measurements were taken with all M1_DAMP gains at -1, except for M1_DAMP_P, which was set to -0.2. Similarly, Y, All M1_DAMP gains were -1, except for M1_DAMP_Y, which was set to -0.2.

Ivey and I used her vectfit3 scripts to fit the transfer functions. The fits were committed to the SUS SVN under revision 12616. They live in 'sus/trunk/HLTS/Common/FilterDesign/Estimator/'

We made a few minimal changes to the original output from vectfit to match our expectation of the plants:

• Vectfit3 does a fantastic job at fitting the M1 drive to M1 transfer functions [see for example the first attached image]. However, to do so, it often adds a pair of high-frequency right-half-plane zeroes to match the phase delay that comes from the anti-aliasing filter that's a part of the TF measurement process. We often remove these zeroes entirely from the fit. This results in fits that look like the yellow trace in the first attached figure.
• We ensured that all zeroes on the fitted M1 drive to M1 transfer functions are in the left half of the complex plane. This is because we don't want to risk creating right-half-plane poles if we increase the gain of the damping through the estimator path.
• The Suspoint P and Suspoint L to M1 P transfer functions are expected to have 1 or 2 pairs of right-half-plane zeroes. In this case, we worry much less about the risk of creating unstable poles because these transfer functions are relevan in feedfordward-type paths only. Therefore, we tend to leave the zeros where vectfit3 places them.

The images of the resulting filters, together with the data that Oli took are summarized in the attached pdfs.

In order of appearance, the zpk of the fits are:

Suspoint Y to M1_DAMP_Y fit

    'zpk([-0.012+20.621i,0,0,-0.012-20.621i,-0.012+11.426i,-0.012-11.426i],[-0.218+6.292i,-0.218-6.292i,-0.382+14.697i,-0.382-14.697i,-0.226+21.579i,-0.226-21.579i],-0.001)'

M1 drive Y to M1_DAMP_Y fit

    'zpk([-0.024-8.341i,-0.024+8.341i,-0.011+19.405i,-0.011-19.405i],[-0.088+6.403i,-0.088-6.403i,-0.115+14.485i,-0.115-14.485i,-0.069+21.379i,-0.069-21.379i],13.34)'

Suspoint P to M1_DAMP_P fit

    'zpk([-2.428-2.295i,-2.428+2.295i,-0.795-9.324i,-0.795+9.324i,-0.011-22.26i,-0.011+22.26i,0.034-5.811i,0.034+5.811i,0.382-13.672i,0.382+13.672i,1.168-1.459i,1.168+1.459i],[-0.507-1.499i,-0.507+1.499i,-0.395-10.253i,-0.395+10.253i,-0.204-4.167i,-0.204+4.167i,-0.141-4.759i,-0.141+4.759i,-0.13-13.137i,-0.13+13.137i,-0.066-22.16i,-0.066+22.16i],-0.001)'

Suspoint L to M1_DAMP_P fit

    'zpk([-0.773-7.242i,-0.773+7.242i,-0.635-18.11i,-0.635+18.11i,0.301-20.227i,0.301+20.227i,1.062-6.916i,1.062+6.916i,-99.035,-0.197,0.331,45.41],[-1.293-19.638i,-1.293+19.638i,-0.33-10.141i,-0.33+10.141i,-0.289-13.191i,-0.289+13.191i,-0.162-4.1i,-0.162+4.1i,-0.122-4.732i,-0.122+4.732i,-0.087-22.103i,-0.087+22.103i],0)'

M1 drive P to M1_DAMP_P fit

    'zpk([-0.339-4.576i,-0.339+4.576i,-0.031-21.157i,-0.031+21.157i,-0.009-5.455i,-0.009+5.455i],[-0.298-13.183i,-0.298+13.183i,-0.205-4.126i,-0.205+4.126i,-0.138-4.803i,-0.138+4.803i,-0.092-22.128i,-0.092+22.128i],80.907)'

TITLE: 08/26 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 152Mpc
INCOMING OPERATOR: Ibrahim
SHIFT SUMMARY:
We tried to run an Initial_ Alignment but SRC aligning didn't work because the New Whitening Chassis or cable that was installed had an issue.
NLN @ 21:14:27 UTC
Back to Observing by 21:20:06 UTC

21:52 UTC Tyler started pushing his rocks around with the tractor over at the far end of the Staging building.
22:50 UTC Tyler's tractor work has lost traction with the commissioning crew and there will be no more tractoring rocks around while locked.

LOG:                                                                                                                                                                                                                                  

TITLE: 08/26 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 153Mpc
OUTGOING OPERATOR: Tony
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 5mph Gusts, 2mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.09 μm/s
QUICK SUMMARY:

IFO is in NLN and OBSERVING as of 21:14 UTC

IFO is still behaving. Expecting a quiet shift.

J. Kissel

After today's H1 SUS SR3 Pitch Estimator's inclusion of the Sus. Point L to M1 P feed forward from the HAM5 ISI GS13s (where we had mistakenly only installed Sus. Point P to M1 P) -- see LHO:86567, I now compare the times of ASC signals (using 0.02 Hz binwidth, 64 sec FFT chunks, 30 averages, and a Hanning window with 50% overlap):
    2025-08-20 18:29 UTC - Both P and Y Estimators are OFF 
    2025-08-24 18:18 UTC - Both P and Y Estimators are ON, but for the P estimator, only the Sus. Point P to M1 P contribution is included in the GS13 FF
    2025-08-26 22:00 UTC - Both P and Y Estimators are ON, and for the P estimator, both P to P and L to P contributions are included in the GS13 FF.

I'm showing only the control signals, and only the ASC DOFs which are impacted by SR3: DHARD, MICH, SRC1, and SRC2; both pitch and yaw.

In All DOFs, the 0.64 and 0.75 Hz modes that had been made worse with only the P to P model of suspension point contribution have now been restored to no-estimator levels.
In some DOFs, the 1-10 Hz broadband motion is just barely improved, but enforces the conclusion that SR3 is only partially, if not 'not the dominate contribution' to the ASC signals. 
Here's a fun one for you -- look at SRC2 Y CTRL -- and look at how much the SRC2 *yaw* motion has changed from including the *longitudinal* suspension point contribution to M1 *pitch* top mass. #ThrowsHandsInAir

But -- overall -- with the improvements and all design intent included -- the SR3 P and Y estimators slightly improve the ASC noise from 1 to 10 Hz. Great!

As Oli notes in LHO:86551 comparing all of these different configurations from totally different days and times is dubious. We'll get "official" versions of all of these ON vs. OFF configurations on Thursday 8/28.

I also attach the local estimator metrics for pitch described in LHO:86553, comparing "only Sus Point P to M1 P modeled contribution" against "P to P and L to P sus point to M1 contribution." That similarly shows that L to P contribution forms a good fraction of the signal needed for damping.

This logpost is a follow up to the executive summary on PR3 OSEM estimator Filter and Blend design [LHO: 86563]

Edgard, Brian, Ivey.

We used Brian's scripts to generate the blends for the PR3 OSEM estimator. We tuned these blends to the specific resonances of PR3 (which we expect to differ from SR3, as explored by Oli in [LHO: 86554]. We emphasized trying to match the bumps in the OSEM filter with the various resonances of the M1 to M1 plant [see in the figures attached].

The scripts used to create the filters, together with a script to load them into foton were updated to the SUS SVN inside 'sus/trunk/HLTS/Common/FilterDesign/Estimator'.

For pitch:
The pitch blends were created using 'blend_PR3_pitchv2.m' (see first pdf attached). The filters follow the same design principle as Brian did in [LHO: 86510] and [LHO:86452]. The blends are created by making the OSEM bandpass by adding an overall low-pass filter with four low-Q bumps  that match the observed resonanced of the M1 to M1 plant. The high-frequency gain of this filter does not asymptote to zero to keep the phase of the bumps close to zero at the resonances of the modeled PR3 M1 to M1 plant, while not creating a zero in between bumps.
The zpks are:

model_filter =

    'zpk([-0.083+22.156i,-0.083-22.156i,-0.097+13.118i,-0.097-13.118i,0,-0.037+4.136i,-0.037-4.136i,-0.045+4.738i,-0.045-4.738i],[-0.188,-0.171+4.106i,-0.171-4.106i,-0.199+4.771i,-0.199-4.771i,-0.438+13.125i,-0.438-13.125i,-0.37+22.177i,-0.37-22.177i],0.9)'

osem_filter =

    'zpk([-1.807+20.726i,-1.807-20.726i,-2.733+10.99i,-2.733-10.99i,-8.429,-0.227+4.431i,-0.227-4.431i,-1.381+2.186i,-1.381-2.186i],[-0.188,-0.171+4.106i,-0.171-4.106i,-0.199+4.771i,-0.199-4.771i,-0.438+13.125i,-0.438-13.125i,-0.37+22.177i,-0.37-22.177i],0.1)'

For yaw:
For the yaw estimator, we used 'Estimator_blend_skinnynotch_PR3yaw_20250825.m'  which follows the design procedure on [LHO: 86265]. In this case the procedure is more similar to designing blends for the ISI: we pick a rolloff for the Highpass (model filter) and Lowpass (OSEM) filter, but add a few notches onto the model filter. Then by using the SEI SVN function 'maketruecomplements_tol' they are turned into complementary blends.  The advantage of this process is that we can ensure the OSEM filter rolls off at high frequencies. One disadvantage is that it is a bit harder to tune the amplitude and phase of the OSEM blend around the suspension resonances.
The zpks are

model_filter =

    'zpk([-0.306+21.389i,-0.306-21.389i,-0.242+14.516i,-0.242-14.516i,-0.128+6.404i,-0.128-6.404i,0],[-1.528-21.337i,-1.528+21.337i,-1.21-14.467i,-1.21+14.467i,-0.641-6.374i,-0.641+6.374i,-0.628],1)'

osem_filter =

    'zpk([-0.81-18.387i,-0.81+18.387i,-0.473-9.928i,-0.473+9.928i,-0.216-3.503i,-0.216+3.503i],[-1.528-21.337i,-1.528+21.337i,-1.21-14.467i,-1.21+14.467i,-0.641-6.374i,-0.641+6.374i,-0.628],6.034)'

FAMIS26547

Script reports ETMX_ST1_CPSINF_V2 is high. HAM3 H2 also seems high.

I unplugged two unused extension chords and I also unplugged what is labeled as the PCALX camera computer, but it is really the the computer to take pictures of ITMX from the spool. The computer is off and not being used, so I unplugged it. I turned the lights off as I left.

J. Kissel, E. Bonilla

Thanks to the hard and quick work of the Stanford team overnight designing blend filters and super sensor model filters (LHO:86563), I was able to install everything needed to get the H1SUSPR3's estimator up, running, and functional this morning. After having run it for bit during maintenance (and thus corner-station sensor correction was off), I've turned the "use OSEMs or use Estimator" switch to "use OSEMs" such that the SUS is performing in a functionally equivalent way as "no estimator." We'll run like this until (a) I make some plots analyzing the performance and (b) Until Thursday's commissioning period when we're in nominal low noise, so we can do similar ON vs. OFF comparisons with ASC as our metric.

The P and Y estimators were ON from 2025-08-26 18:05 UTC to 19:00 UTC.

Some extra design points beyond whats made in LHO:86563, with the mind-set of "can we 'just' copy and paste SR3's filters into PR3?"
In short: No.
In long: 
    The existing OSEM-only damping is different -- all SR3's damping loop's overall EPICs gain is -0.5, where PR3's is -1.0. This is demonstrated by LHO:86554, that means the damped M1 drive to M1 response "damped plant" is different. Namely, on resonance, the loop suppression 1/(1+G), is different because G is different, and thus P/(1+G) is different. This has the effect of shifting the fundamental mode frequencies and changing the residual Q. *That* means two things:
    (1) that the OSEM vs. Estimator blend filters -- which are relatively tight notches around resonances -- in principle, should be different. That being said, depending on the performance we end up getting we could *see* if making the blend filters generically wide enough would work. But, for now, we err on the side of "let's make the blend filters specific" because we have the measurements and the person power.
    (2) The "undamped plant" measurements for the estimator -- which are really "lightly damped" plants with whatever loop suppression is left from the broadband OSEM damping that's still always used; an EPICs gain of -0.1 for SR3 and -0.2 for PR3's damping loop controllers -- are different. So, the filters that are modeling that response -- the Sus. Point drive to M1 response filters and the M1 drive to M1 response filters -- will also necessarily be different. However, the differences are almost entirely resonance shifts and Q changes that are proportional to the differences in 1/(1+G) of the light damping (one with scaled with G = -0.1 and one with G=-0.2). Said differently, so far, only the on-diagonal M1 to M1 transfer functions are proving to be needed, and only the P to P, L to P, and Y to Yaw suspension point to M1 transfer functions are needed, and these are almost identical between PR3 and SR3.

I'll put a comparison of the filters and details of the installation in the comments.

M. Todd, C. Compton, S. Dwyer

We changed the gain settings in TCS-SIM that convert the powers of each actuator (including self-heating) to surface defocus for calculating the overall radius of curvature of each test mass at a given thermal state.

The motivation for this was that the simulation seems to be largely overestimating the Higher Order Mode spacing. Hopefully, with these new predictions, we will observe better agreement between the simulation and HOM measurements.

We also changed the absorption values using values taken from alog 80714 for the ITMs, and using galaxy for the values for the ETMs.

Jeff, Oli

On Thursday (86507) I alogged the differences we were seeing in the ASC with the SR3 estimator on. The time that I was taking as our 'reference time' for the estimator off, however, doesn't seem like it was a good time showing the lowest the ASC noise could be. You could say this caused us to over estimat(or) the differences.
So I plotted some more times with the estimator off, then with the estimator on, and I found that maybe the SR3 noise is limiting the ASC noise less than shown in 86507. However, I also found that below 0.2 Hz, where we thought that the estimators were elevating the noise, that also seems to have been not related to the estimator, so that is something we might not have to worry about. 
Of course the peaks at 0.6 and 0.7 Hz are elevated in the estimator plots below due to not damping them in the inital blend filter (mentioned in 86507), and this is something that we partially fixed this morning (86544), and will be working on further damping at the next available commissioning time.

There are still times where the estimator on makes the noise better at some frequencies, but there are also other times where the estimator is on, but something else is limiting the noise, so it looks like SR3 isn't limiting the noise very much at all. It will still be interesting to see if adding estimators onto the rest of the SRC give us different results.

In the plots below, I am showing the variation in noise with the estimators off and the estimators on,
The 'bad' time for the estimators OFF is: 2025-08-17 09:00 UTC (green)
The 'good' time for the estimators OFF is: 2025-08-20 18:29 UTC (blue)
For the estimators ON times, they're both 'good' and 'bad' at different frequencies, so I'll just list their times:
2025-08-21 16:35 UTC (red)
2025-08-24 18:18 UTC (gold)

DriptaB, TonyS, RickS

Andrei, Naoki, Sheila

Following the research of aLOG 78125 and aLOG 78262, we aimed to quantify the value of backscattering from the ZM2 and ZM5. We performed backscattering measurements under the assumption that modulation of the optical path between scatterer and interferometer would introduce additional noise in the DCPD spectrum [1-4].

We used data from the H1:OMC-DCPD_SUM_OUT_DQ channel (calibrated to mA of photocurrent) for the times of aLOG 78125. We've then calculated RIN with correction for the DARM control loop. Using Eq. 25 from [1], we performed manual fit. Although we couldn’t perfectly fit within the range from 15 Hz to 21 Hz (probably because of the chosen Welch's transform parameters), we were still able to obtain meaningful results for the backscattering coefficients (see Fig. Backscattering_meas.png). The resulting coefficients are below:

r_ZM5 ≈ 4 x 10^-4

r_ZM2 ≈ 0.1 x 10^-4

Also note, that the amplitude of the excitation used for fit is several times larger than that we've measured from the H1:SUS-ZM#_M1_DAMP_L_INMON channel (1.2 μm unstead of 0.4 μm).

Code that was used for this calculation is attached to this report. OM1_fringewrapping_test.m (Sheila's code) was used to calculate RIN, main.nb was used for manual fit and plotting.

[1] Martynov, D. V., Hall, E. D., Abbott, B. P., Abbott, R., Abbott, T. D., Adams, C., ... & McIver, J. (2016). The sensitivity of the Advanced LIGO detectors at the beginning of gravitational wave astronomy. Physical Review D, 93(11), 112004.

[2] Ottaway, D. J., Fritschel, P., & Waldman, S. J. (2012). Impact of upconverted scattered light on advanced interferometric gravitational wave detectors. Optics express, 20(8), 8329-8336.

[3] Nguyen, P., Schofield, R. M. S., Effler, A., Austin, C., Adya, V., Ball, M., ... & Moreno, G. (2021). Environmental noise in advanced LIGO detectors. Classical and Quantum Gravity, 38(14), 145001.

[4] Fricke, T. T. (2011). Homodyne detection for laser-interferometric gravitational wave detectors. Louisiana State University and Agricultural & Mechanical College.