RickS, SudarshanK, CraigC, JeffreyK, DarkhanT

To calculate DARM time-varying parameters we use EPICS records precalculated from DARM OLG TF model, as described in T1500377-v7.

Earlier we reported that EP1 calculated from the canonical DARM model for ER8/O1 had an unexplained phase discrepancy (see LHO alog 21386) that came from measured TF taken between x_tst excitation point to DARM_ERR at cal. line frequency being off by -136.7 degrees compared to TF calculated accoring to Eq. 5 in T1500377 from DARM model. In this alog we outline current status of our investigations of this discrepancy.

The negative sign of the DARM feedback loop that was shown on the simplifed DARM loop diagram in T1500377-v7 was not placed where it actually appears. This update affects only how x_tst line to DARM_ERR (and DARM_CTRL) TF is calculated in the DARM model; Pcal and x_ctrl line to DARM_ERR (and DARM_CTRL) TF equations remain valid in T1500377-v7.

Figure below shows the correct location of the sign flip of the DARM loop (that's not included into C, D or A) accroding to our investigations; we'll update T1500377 with the correct diagram in the next version. (notice that this simplified diagram, as it was cited in T1500377, was borrowed from G1500837 where it might also need to be corrected)

In ER8/O1, since now we have x_tst (ESD) calibration line that is injected from the suspension front-end model (inside of the block "A" on the diagram), additional to the knowledge that the sign flip is between the x_ctrl (DARM line) excitation point and ΔL_ext, we also need to know the location of it w.r.t. the x_tst excitation point.

With the -1 sign flip placed in the new location Eq. 5 and Eq. 7 in T1500377 should not have a "-1" factor. Hence, Eq. 19 will also not have a "-1" factor, meaning that our calculation of EP1 was incorrect by 180 degrees.

Currently there's an unexplained +44.4 degrees of discrepancy (instead of earlier -136.7) between measurement x_tst / DARM_ERR vs. the model itself, that appears in EP1 (we looked into the measurement of x_tst / DARM_ERR on Sep. 10). We are investigating the source of this discrepancy.

The location of the sign was confirmed by using measurements of

• L3 stage (ESD) driver excitation to DARM_IN1 TF,

meas. file: CalSVN/Runs/ER8/H1/Measurements/FullIFOActuatorTFs/2015-08-29/2015-08-29_H1SUSETMY_L3toDARM_LVLN_LPON_FullLock.xml

• input of "D" to input of "A" (exported from canonical DARM OLGTF measurement)

meas. file: CalSVN/Runs/ER8/H1/Measurements/DARMOLGTFs/2015-09-10_H1_DARM_OLGTF_7to1200Hz.xml

• input of "A" to output of "C" (exported from canonical DARM OLGTF measurement)

meas. file: CalSVN/Runs/ER8/H1/Measurements/DARMOLGTFs/2015-09-10_H1_DARM_OLGTF_7to1200Hz.xml

When the Operator found the ISIs in the wrong SDF state, 21609, they reported digging through the logs but not finding anything.  After reporting what the filters do, they accepted the changes and went to observing.  This is just the opposite of what we should do.  If no supporting evidence is found for the change, reverting to the .snap values is the correct path.  Of course there is some risk to the IFO lock in filter switching, not very appealing after being out for so long.

In the Evening shift operator's summary, The TM ISIs seem to be reported back in high gain:

02:05 Attempt to bring back End Station ISIs seems succesful. GS 13s back to high gain. Seismic graph is showing 3µ/S.

02:09 Ditto for ITMs

02:10  Begin bringing up Input and Output HAM SEI.

02:15 Kissel brought ESDs back and restored ETM alignment.

02:31  All SEI back to nominal isolated states. GS13 gains switched back to HIGH.

This sort of implies the ITMs were put back into High gain but that is not the case.  They were switched to low gain (H1:ISI-ITMY_ST2_GS13INF_H1_SW1R: FM4 & 5 On) 0005 utc and remain there still.  At this point the SDF should have been consulted for proper configuration.

The SEI system is untouch by IFO locking guardians.  SEI SDFs should be green well before looking at going into Observation mode.

One may argue that this difference is not critical: these filters compensate for changes in the analog gain and whitening.  The output level of the filter bank is unchanged.  On the other hand in nominal seismic environment, having greater SNR when digitizing the GS13 signal gives better ISI Damping and Isolation.

Four burst signals have been injected into H1 since the new inverse actuation filter was installed Sunday evening (Timeline of CAL-CS Calibration Filter Updates), with different waveforms:
GPS 1126270500  -  White noise burst, frequency 125 Hz, bandwidth 150 Hz
GPS 1126280500  -  White noise burst, frequency 300 Hz, bandwidth 350 Hz
GPS 1126300500  -  Sine-gaussian, frequency 20.82 Hz, Q=7.32
GPS 1126310500  -  Sine-gaussian, frequency 413.0 Hz, Q=85.1

The low-frequency, low-Q sine-gaussian offers the clearest check of the calibration amplitude and phase among these signals.  (It would be better to use detchar injections, i.e. a set of sine-gaussians at a range of frequencies, as was done during ER7, but we have not performed any detchar injections during ER8 yet.)  I used a matlab script (attached) to plot the intended strain waveform (the file produced by Chris P. and read by tinj to inject the signal) and the H1:GDS-CALIB_STRAIN channel from the hoft frames in the archive at Caltech.  Both have been bandpass filtered bidirectionally with 'filtfilt' around the frequency of interest.  I also did a crude matched filter, stepping the intended strain waveform by integer samples and considering both upright and inverted overlaps with the data.  As you can see from the plot, the signal that came through in the H1:GDS-CALIB_STRAIN channel is consistent with being *inverted* relative to the intended strain signal.  That was also the case in ER7, but we thought the recent calibration work and a careful look at sign conventions would have resolved that.

Is there any possibility that the GDS calibration process running on Monday, producting H1:GDS-CALIB_STRAIN, had not yet been updated with the final resolution of sign convention?

TITLE:  Sep 17 OWL Shift 07:00-15:00UTC (00:00-08:00 PDT), all times posted in UTC

STATE Of H1: Observing at 77 Mpc

SUPPORT: Sheila

SHIFT SUMMARY: After 12+ hours of not locking, we are back in business. I redid the initial alignment followed the printed Initial Alignment Checklist on the desk after the seismic nosie came down to almost nominal because PRMI looked hopeless. LLO is still trying to acquire lock.

INCOMING OPERATOR: Patrick

Activity log:

8:00 Begin initial aligment. Adjusted PR3 to maximize COMM beatnote. Spent 10 minutes at INPUT_ALIGN without luck. Trended IM4 and PR2 back to the last time the ifo was locked. I brought IM4 back to where it was. Touched PR2 YAW to get 00 mode on As Air camera.

8:04 Darkhan left

9:11 Craig left

9:12 BS ISI WD tripped during MICH_DARK_LOCK twice. Requested down and waited until the optic became settled and moved on.

         ENGAGE_ASC_PART3 took ~5 minutes.

        Guardian stalled at DC_READOUT_TRANSITION (alog21608). OMC was not ready for handoff and was locked at the wrong mode. I called Sheila for help but the ifo lost locked shortly.

10:52 Locked at NOMINAL_LOW_NOISE

11:13 Back to Observing after I cleared the SDF diff.

13:15 Lockloss. More earthquake....

13:46 Locked at NOMINAL_LOW_NOISE

13:48 Undisturbed.

15:00 Hand off to Patrick.

The ifo is locking and observing again. I did an initial alignment as soon as the seismic noise settled. Wind speed below 10mph. Minimal seismic activity. LLO is down.

After almost 12 hours of not locking, the ifo is back at 70Mpc. OMC locked at the right mode this time so I still have no idea what's wrong earlier. Terramon has just reported another 5.5M earthquake in Chile. We might lose lock again...

SDF is reporting 6 differences in ISI ITMX and ISI ITMY. Unable to go to Observe mode. I'm digging through the alog. 

C. Cahillane

Per Jeff's request, here are the Actuation stage residual weighted means in time based on our three measurement dates, August 26, 28, and 29.
Essentially, I took the residuals already computed in , separated them by measurement date (26, 28, 29), separated them by acutation stage (L1, L2, L3), and computed each weighted uncertainty and weighted mean.
For plot values run the compare_actcoeffs_ER8_craig_extrapolation.m file and use the plotmagwm, plotmagunc, plotphasewm, and plotphaseunc matrices.
The matrix elements are as expected:  First number corresponds to data, second to actuation stage:
            |  L1  |  L2  |  L3  |
Aug 26-
Aug 28-
Aug 29-

TITLE: Sep 17 Owl Shift 07:00-15:00UTC (00:00-08:00 PDT), all times posted in UTC

STATE Of H1: Lock Acquisition

OUTGOING OPERATOR: Ed M.

QUICK SUMMARY: Attempting to lock the interferometer. I couldn't get any flashes on POP 18 and 90 while trying to lock PRMI. Since Ed did the initial alignment when the ground motion was still high I think I might try to do the initial alignment again when the ground motion become less active.

TITLE:  Sep 16 EVE Shift 23:00-07:00UTC (16:00-00:00 PDT), all times posted in UTC

STATE Of H1: Down

LOCK DURATION: N/A

SUPPORT: Hugh, Jeff K, Sheila

INCOMING OPERATOR: Nutsinee

Link

A little late with this entry due to Mother Nature:

TITLE: Sep 16 EVE Shift 23:00-07:00UTC (16:00-00:00 PDT), all times posted in UTC

STATE Of H1: Observing

OUTGOING OPERATOR: Patrick

QUICK SUMMARY:Full control room.. Wind is blowing just under the 20mph mark. Seismic activity quieting down from earlier earthquakes. All lights at Mid, End and LVEA stations are off. Then...Chilean earthquake 8.3Mag caused lockloss. Working with Hugh to get tripped seismic systems to happy places to ride this out.

Attached is agallery of 5 "dust" glitches. Still clueless of what they are, but
 - ETMY saturation is a symptom, not a cause  - it is not possible to produce such a white glitch from saturating a drive.
 - The DCPD spectrum shows a roll-off for all of them
 - But the roll-off frequency (i.e. glitch duration) varies significantly = from about 300Hz to 3kHz.


Example 2:
GPS: 1126294545
UTC: Sep 14 2015 19:35:28 UTC
ETMY saturation: yes

Example 3
GPS: 1126437892
UTC: Sep 16 2015 11:24:35 UTC
ETMY saturation: yes

Example 4
GPS: 1126434798
UTC: Sep 16 2015 10:33:01 UTC
ETMY saturation: yes

Example 5
GPS: 1126441165
UTC: Sep 16 2015 12:19:08 UTC
ETMY saturation: yes

Example 6
GPS: 1126442379
UTC: Sep 16 2015 12:39:22 UTC
ETMY saturation: yes

Nairwita Mazumder, Rich Abbott

A few days back Jim noticed  (alog ) that the "Bumbling line" which varies over a large frequency range is again back on ETMX seismic channels . This was first noticed on March and disappeared before ER7 and again was seen from 4th August. One can see the lines at all the horizontal and vertical sensors on ETMX. 

I have attached a pdf containing some follow up work done during Rich's recent visit to LHO. The first plot in the pdf is the spectrogram of ETMX GS13 on 26th August. It can be seen that there are multiple wandering lines having a fixed offset.  We were suspecting that some magnetometers at the End X might be the culprit (as we could not find any correlation between temperature fluctuation  with the line ). 

The second and third plots are the spectrum of H1:PEM-EX_MAG_EBAY_SEIRACK_Z_DQ and H1:ISI-ETMX_ST2_BLND_Z_GS13_CUR_IN1_DQ for 2nd August and 26th August respectively. The red one is for 2nd August when the bumbling line could not be found and the blue one is the recent data (26th August). It is clear that the peaks appearing on  ISI-ETMX_ST2_BLND_Z_GS13 after 3rd August are correlated with the peaks of the spectrum (which also appeared around the same time) of SEIRACK magnetometer .

The plots on the second page shows the coherence between GS13 and the magnetometers in the VEA and SEIRACK. It looks like  the magnetometer on the SEI rack has stronger coherence with GS13 sensors than the magnetometer located at VEA .  I have marked two points (blue and red cross)  in the coherence plots to highlight two of the many peaks.