TITLE: 04/02 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Observing at 69Mpc
INCOMING OPERATOR: TJ
SHIFT SUMMARY: One lockloss of unknown cause. Otherwise no issues with relocking or wind (wind is still at ~30mph, but not effecting range).
LOG: See previous aLogs.
Following up on this earlier observation of a change point in DARM combs on March 14 and on comments added by Evan and Ansel, I tried looking at possible correlations between optical lever laser power levels and combs seen in EX and EY magnetometers. The bottom line is that there are such correlations, as documented in detail in the attached annotated slides with posted spectra at a variety of power levels (as measured by H1:SUS-ETMX/Y_L3_OPLEV_SUM_OUT_DQ). The figures below show EX and EY before/after spectra. In summary, the spectra show narrow lines before March 14 in combs of ~1-Hz spacing with various offsets (EX worse than EY). During periods when the laser powers were lowered, the spectra were contaminated by broadband noise (motivation for keeping the power high, I believe). When the power was raised to higher than it was prior to March 14, the broadband power dropped again, the lines persisted and were joined by new lines with 1-Hz spacing offset from integer frequencies by ~0.25 Hz, a comb observed to be present in DARM following March 14. The apparent creation of a new comb in DARM from these lasers may hint that other combs seen for a long time in DARM and in magnetometer spectra may also arise from these lasers. Whether the mechanism is though the optical lever damping, as suggested previously for glitches, or through another coupling, such as ESD power supply contamination from the laser supplies, is not clear to me. Fig 1: EX magnetometer spectrum before maintenance work on March 14 (Interval "A" on 1st attached slide file) Fig 2: EY magnetometer spectrum before maintenance work on March 14 (Interval "P" on 1st attached slide file) Fig 3: EX magnetometer spectrum before maintenance work, on March 15 (Interval "Q" on 1st attached slide file) Fig 3: EY magnetometer spectrum before maintenance work, on March 15 (Interval "V" on 1st attached slide file) Attachment 1: Annotated slides showing spectra before / after many change points on March 14/15 of EX laser power Attachment 2: Annotated slides showing spectra before / after a handful of change points on March 14/15 of EY laser power
Heads up on this: Jason plans to swap the ETMY laser tomorrow (see WP 6555), not necessarily because of this study, but it'll be another "before vs. after" data point. Also -- do we suspect a coupling mechanism for this correlation to DARM? The bandwidth of the optical lever damping loops is quite narrow around 0.3-0.5 [Hz], and control is applied only at the penultimate stage, which means it'll get a factor of 1/f^2 above ~5 Hz. Further, it's angular control as well, so you'd need a pretty high angle-to-length coupling coefficient... Did you see any improvement in the combs seen in DARM after Sheila installed a better cutoff filter (see LHO aLOG 34988)?
Following up on Jeff's question, below are spectral comparisons of pre-March 14, the period between March 14 and March 21, and the period afterward. I don't see evidence of a significant change in the comb structure in DARM after the damping loop rolloff adjustment on March 21. Included are zooms around four teeth in the 1-Hz comb on 0.25-Hz offsets from integer frequencies. Fig 1: 20-60 Hz Fig 2: Zoom around 20.25 Hz Fig 3: Zoom around 21.25 Hz Fig 4: Zoom around 22.25 Hz Fig 5: Zoom around 23.25 Hz
Nothing apparent on FOMs. Unknown cause.
Back to Observing at 17:21 UTC.
TITLE: 04/02 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Observing at 61Mpc
OUTGOING OPERATOR: Jeff
CURRENT ENVIRONMENT:
Wind: 35mph Gusts, 30mph 5min avg
Primary useism: 0.15 μm/s
Secondary useism: 0.44 μm/s
QUICK SUMMARY: High winds are affecting our range a bit, but we have been locked for ~24 hours.
Looking at the summary pages, it looks like the range drop is coincident with increase in the 10-30 blrms motion at the corner station. I suspect the recent wind-related range drop/glitches are related to the 8-18 Hz input beam-tube vibration-related coupling that Robert and co. showed recently. This is probably not surprising to most, but I just wanted to suggest this explicitly since wind wasn't mentioned in Robert's alog. Hopefully fixing that problem will also fix wind-range coupling.
Shift Summary: Run A2L check script; Both Yaw and Pitch are elevated. Will run the correction script when possible.
Overall a good observing shift.
In the last hour, the wind has come up to Near Gale conditions with gusts well into the full Gale range (40 mph+). Primary microseism for the End Stations has correspondingly risen to near 0.9um/s. Range has dropped to 63.9 Mpc. There is a 0.723um/s R-Wave predicted to hit the site around 15:00 (08:00), the result of a Mag 5.2 earthquake near Bengkulu Indonesia. So far, no indications of the R-Wave arrival.
10:36 (03:36) GRB Alert - Both sites in Observing
Beam position based on exciting the pitch(yaw) DOF and then changing P2L(Y2L) gain to minimize the peak. Both measurements use a sign convention that is consistent with UR coil values. The Dec 2013 alpha numbers are as posted, however the beam distance numbers have been recalculated. In Dec 2013 the conversion from alpha to mm was 37.5mm/alpha, and the current conversion is 42.2mm/alpha.
| 13 Dec 2013 | 21 Mar 2017 | change | |||
| alpha | beam distance from center, mm | alpha | beam distance from center, mm | mm | |
| MC1 pitch | -0.043 | +1.81 | -0.057 | +2.42 | +0.6 |
| MC1 yaw | +0.029 | +1.22 | +0.089 | +3.76 | +2.5 |
| MC2 pitch | -0.062 | +2.62 | -0.183 | +7.72 | +5.1 |
| MC2 yaw | -0.048 | -2.03 | -0.020 | -0.084 | +1.2 |
| MC3 pitch | +0.041 | -1.73 | -0.051 | +2.15 | +3.9 |
| MC3 yaw | -0.052 | -2.19 | -0.135 | -5.70 | -3.5 |
The animation that's attached shows the ideal IMC alignment in a dashed magenta line, the Dec 2013 alignment in red, and the Mar 2017 alignment in blue. Green markers show the optics, squares are MC1, triangles are MC2, and circles are MC3.
The lines and markers accurately represent the optics and the beam changes, but are not to scale. I altered some numbers to make the changes visible in this animation.
| 13 Dec 2013 | 21 Mar 2017 | change | |||
| alpha | beam distance from center, mm | alpha | beam distance from center, mm | mm | |
| MC2 yaw | -0.048 | -2.03 | -0.020 |
-0.84 |
+1.2 |
TITLE: 04/02 Eve Shift: 23:00-07:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Observing at 53Mpc
INCOMING OPERATOR: Jeff
SHIFT SUMMARY: Locked for 15.5hours, wind has been a steady 15mph and useism is rising up to 0.5um/s. There was a large glitch just now that is showing up on the glitchgram in almost the entire shown frequencies.
LOG:
06:52 GRB
TITLE: 04/01 Eve Shift: 23:00-07:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Observing at 70Mpc
OUTGOING OPERATOR: Travis
CURRENT ENVIRONMENT:
Wind: 19mph Gusts, 16mph 5min avg
Primary useism: 0.04 μm/s
Secondary useism: 0.34 μm/s
QUICK SUMMARY: Smooth sailing at 70Mpc for almost 8hours
TITLE: 04/01 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Observing at 70Mpc
INCOMING OPERATOR: TJ
SHIFT SUMMARY: Observing for ~8 hours. Relocked early in the shift. No issues to report.
LOG: See previous aLogs.
Locked for ~4 hours. No issues.
Begin 1 hour stand down.
No issues relocking.
Shift Summary: Run A2L check script; Pitch is around 0.6, Yaw is below reference. Lost lock, reason unknown. Had trouble with ALS locking, finding IR and DRMI_1F. Ran initial alignment. On relocking, broke lock, twice on FIND_IR ALS_DIFF. Third time made it all the way to NLN. Back to Observing.
Ran A2L check script. Pitch is up to 0.9, Yaw is OK. Will run correction script when opportunity presents.
Damping unruly PI Modes 27 & 28
Lost lock a second time, with no apparent cause. Did not need realignment. During FIND_IR lost lock several times during ALS_DIFF. From the log it looked like the offset was being moved from 1368 to 0 and then back to 1368. The lock was breaking on the second jump of the offset to 1368. Made it through FIND_IR just as Travis was coming on shift. Relocking is proceeding.
TITLE: 04/01 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Lock Acquisition
OUTGOING OPERATOR: Jeff
CURRENT ENVIRONMENT:
Wind: 7mph Gusts, 4mph 5min avg
Primary useism: 0.03 μm/s
Secondary useism: 0.26 μm/s
QUICK SUMMARY: Unlocked before my arrival. Relocking seems to be going OK with none of the issues noted by previous operators thus far.
First 3 hours of shift were good observing time. Lost lock - reason unknown. Had trouble with ALS Locking, IR, and DRMI_1F, so ran initial alignment. On relocking, broke a couple of times on FIND_IR for ALS_DIFF. After this relocking went OK. Reset the ETMX RMS WD. Finally relocked at NLN. IFO in Observing, 29.2W, and 75.2 Mpc. Wind and seismic are low.
