The DCS C01 hoft frames are now available up to 1133178880 == Dec 03 2015 11:54:23 UTC.
See these alogs for further information:
https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=23966 https://alog.ligo-la.caltech.edu/aLOG/index.php?callRep=23263
MID-SHIFT SUMMARY:
After the lock loss that occurred at 17:35UTC by permitted incursions to the LVEA, the wind speeds shot up to the 35mph+ range and have been there since. µSeism is very high ( pushing on 2µm/s). I have been working with Sheila getting more acquainted qith the LockLoss tools. We aren’t missing out on coincidental time with Livingston as they are still investigating their noise /range trouble. EQ bands have even increased from ≈.09 to about .2 µm/s.
16:43UTC. This is with approval from the run coordinator and in sync with LLO doing a noise investigation that is affecting their range.
TITLE: Dec 10 DAY Shift 08:00-16:00UTC (00:00-08:00 PDT), all times posted in UTC
STATE Of H1: Observing
OUTGOING OPERATOR: Patrick
QUICK SUMMARY: Looking good! Locked for 10:53:45. 80Mpc
TITLE: 12/10 [OWL Shift]: 08:00-16:00 UTC (00:00-08:00 PDT), all times posted in UTC STATE Of H1: Observing @ ~ 80 MPc SHIFT SUMMARY: Quiet shift. Winds have remained low. Microseism has trended back up above the 90 percentile. Rode through 5.7 magnitude earthquake in South Sandwich Islands. INCOMING OPERATOR: Ed ACTIVITY LOG: 08:24:59 - 08:25:11 UTC Accidentally out of observing 09:10:08 UTC Out of observing while Kyle fills generator at Y2-8 09:38 UTC Kyle back 09:41:27 UTC Back to observing 5.7 151km E of Bristol Island, South Sandwich Islands 2015-12-10 12:05:15 UTC 10.0 km deep
I have set the pump speed at 40 Hz on the corner station chilled water pump #3, as requested by Robert Schofield.
Following the installation of the PBS on the HWS table to measure the polarization state of the 1064nm light leaking out of the BS_AR surface, I took a quick look at the data from the detectors.
Looking at a 5 hour time series around a couple of lock acquisitions, we see 20-30mV on the S detector vs about 97mV on the P-detector. The X-arm transmission is shown as a guide for when the IFO is locked. Vertical axis is the voltage from the detectors.
Next, if we normalize the time series by the median values of each series, we can see much more noise on the S-detector (some of which is caused by the higher relative electronics noise) but significantly higher low-frequency variations during lock - for example, the amount of S-polarization drops by 30% in the second lock-stretch.
Lastly, the time just around the second lock-loss is shown in detail. The S-polarization oscillation is almost exactly out of phase with the oscillation in the arm and in the P-polarization (which is a strong indication for polarization rotation in the interferometer beam). I need to do some further analysis, but the fact that the SUM of the S+P still shows a strong oscillation indicatest that this is not polarization rotation in the HWS optics.
09:10 UTC Kyle is driving to Y2-8 to add fuel to the generator. I'm not sure if we have been taking it out of observing for this, so I am playing it safe.
09:38 UTC Kyle back 09:41 UTC Back to observing
For future reference Mike L. told me that taking it out of observing was not necessary.
Nutsinee was explaining the violin mode damping filter banks to me. We turned off the output to one of the banks that had a gain of 0 and were dropped out of observing. We quickly turned it back on and went back to observing. According to the verbal alarms log we went out of observing at 08:24:59 UTC and back to observing at 08:25:11 UTC.
TITLE: 12/09 EVE Shift 00:00-08:00UTC (16:00-00:00 PST), all times posted in UTC
STATE Of H1: Observing
SUPPORT: Sheila, Jenne, Evan
LOCK DURATION: 3 hrs
END-OF-SHIFT SUMMARY: Two locklosses. One caused by wind the other caused by the 45mHz rung up. FIND IR was difficult for both relocking. Low wind towards the end of shift. High useism. Using 45 mHz blend everywhere.
Activity:
00:08 Cleared ETMX timing error. Didn't go out of Observing.
00:18 Kyle driving back from Y28
00:53 Evan changed ETMX UIM offset. Out of Observation from 00:53:12-00:59:17
01:00 GRB alert received
01:52 Lockloss. Wind gust reached 36 mph. See alog24094 for details.
03:15:13 GRB alert received
03:15:34 Observing
03:55 Tidal signal started to ring up. Tried turning off ALS Tidal Servo. Didn't help. Tried switching ETMX blend to 90 mHz since we were going to lose lock anyway. Lockloss as a result.
04:40 Switched EX blend back to 45 mHz after two unsuccessful relocking attempts.
05:11 Back Observing.
TITLE: 12/10 [OWL Shift]: 08:00-16:00 UTC (00:00-08:00 PDT), all times posted in UTC STATE Of H1: Observing @ ~ 78 MPc OUTGOING OPERATOR: Nutsinee QUICK SUMMARY: From the cameras: The lights are off in the LVEA. The lights are off in the PSL enclosure. The lights are off at end X. The lights are off at end Y. I can not tell if the lights are on or off at mid X and mid Y. See attached screenshot for seismic. The winds have trended down to between ~ 0 and 5 mph. The ISI blends are on 45mHz everywhere. From pinging: CDS WAP is off at the LVEA. CDS WAP is off at end X. CDS WAP is off at end Y. CDS WAP is on at mid X. CDS WAP is on at mid Y.
Wind speed below 20 mph. Useism still high (at 90th percentile). I accetped the changes Evan made to ETMX L1 LOCK Tramp and gain during the last relock. Guardian still turn the violin mode damping back on despite the fact the Evan has already added a code to turn it off for his ringdown measurement.
Evan, Sheila
We lost lock a few minutes ago (24093) due to a 36 mph wind gust at EY. We are running 45mHz blends on all BSC ISIs now, and microseism is around 0.8um/sec. The first plot shows the wind gust that we think knocked us out.
We then ran both of our saturation lockloss scripts. The second attached plot shows that a saturation of ETMY L1 by a 50mHz signal was the proximal cause of lockloss, which must be from the length drive since this is our only dirve signal sent to ETMY.
Since we can't offload to HEPI above the blend frequency, it seems that we would need length feedback offloaded to M0 to avoid this kind of lockloss in the future.
Many ASC signals also see a large excursion around the time of the lockloss.
Following up yesterday's alog 24062.
We think that the ~650 Hz peak was caused by the ALS COMM VCO beating against the DIFF VCO. At times when the COMM VCO is parked at the lower value (as discussed in the earlier alog) the two VCOs are < 700 Hz apart and this beat shows up in darm. To get rid of this peak, we added a line in guardian so that H1:ALS-C_COMM_VCO_TUNEOFS is set to 2 in full lock. This way, the COMM VCO gets parked at a high value far from the DIFF VCO. See figure 1 if you want to see the actual values of the two VCOs; the top plot is from yesterday (peak present; the two VCOs are within 700 Hz of each other) and the bottom plot is from today (the two VCOs are >10 kHz apart, peak is not present).
Also attached (figure 2) is a darm spectrum comparing yesterday, when this noise was present, to the current lock. It is clear that the peak between 600 Hz and 700 Hz (and the higher harmonic) is now gone. No other peaks have been observed to appear due to this change. We think this has solved the issue, but we should keep an eye out to make sure it does not return. Also, it will be good to keep beating VCOs in mind if similar wandering peaks show up again.
Jordan, Robert, Sheila
When we transition DARM control from EX to EY, we ramp off the DARM input into the EX test/PUM/UIM filter banks.
Since the UIM filter bank has an integrator, this leaves a static offset on the output of this filter bank which is cancelled by the offloading of IMC-F to the UIMs.
However, depending on the size of the offset, this can use up a significant amount of the control range of the offloading (which is set by a digital limiter). Today, the EX offloading was hitting this limiter, causing IMC-F offloading to stop and start (see attachment).
Since the offloading signals were trending even further toward saturation (i.e., greater likelihood of IMC-F saturating and causing lockloss), I dropped the interferometer out of observing and zeroed this offset using two one-minute ramps.
We should modify the ISC_LOCK guardian to do this automatically during lock acquisition.
The offloading completely railed at the end of the most recent lock acquisiton (ca. 03:00:00 Z). I have edited the guardian so that this EX UIM offset is ramped down in the CLOSE_BEAM_DIVERTERS state.
This will result in two SDF diffs on EX.
The alert was received at 01:00:08 UTC. GraceDB said the event actually happened at 00:59:16.64 UTC. We were out of Observing mode for a few minutes for a non-invasive change to ETMX UIM offset from 00:53:12 - 00:59:17 UTC. We think it's reasonable to not veto the alert.
Another GRB alert received at 03:15 UTC (LLO received it first and contacted us). We were at NLN clearing SDF at the time. The data should be good for analysis even though it wasn't in Observing intent (we hit "Undisturbed" button right after).
The mystery ~650Hz noise reported here and here also shows up in the PEM rf antenna (in both 9MHz and 45MHz located in CER and LVEA). Further investigation revealed that this peak shows up in the PEM antenna during lock aquisition at the start of the DC Readout Transition step (if it appears at all; it's not present in every lock--more on this later). At the start of this step the ALS COMM VCO is parked at some value.
To determine whether this VCO could be responsible for the ~650Hz noise, the frequency readback of the VCO was compared to the frequency of the mystery peak in the PEM antenna. Attached (figure 1) is a plot of H1:ALS-C-COMM_VCO_FREQUENCY timeseries on top and spectrogram of the PEM 45MHz LVEA antenna on the bottom. The frequency of the peak seems to track with the VCO frequency if you take into account the fact that the VCO frequency readback is digitized into steps of 8Hz (does anyone know why / can we fix this?).
Also, there appears to be 2 different values where the VCO can be parked. Figure 2 has similar plots to figure 1, over a 28hr stretch which contained multiple locks where the peak was sometimes present. In locks where the peak was present, the VCO was set to ~78.7873MHz. For locks where the peak is not there the VCO was set to ~78.7944MHz. These values correspond with two different values of H1:ALS-C_COMM_VCO_TUNEOFS : ~-1.39 and ~1.25, respectively.
To test this, we tried moving the COMM VCO TUNE OFS slider with the IFO locked (before continuing to NLN / Observing). While initially it looked like the peak in the PEM rf channel moved as the slider was moved, the lock broke before we could conclusively tell. The lockloss occurred right as Sheila was moving the slider. We don't know why this should cause a lockloss, so this is a subject for further investigations (it was windy and ground motion-y at the time so it could have been a coincidence).
Also included (figure 3) is a plot of the VCO frequency (again, 8Hz digitization) and the CER Rack temperature. More data is needed, but it looks like the freqency trends down after the temperature rises.
Finally, there is still the question as to why this is showing up in the 9MHz and 45MHz channels (and, ultimately, DARM). As a first check, I compared 9.100230 MHz and harmonics to 78.7873 MHz and harmonics to see if a beat would show up within 600 Hz. Out to 10 harmonics of the VCO frequency the closest they came to each other was 200 kHz--still a mystery.
Jordan, Robert, Sheila
8Hz is the single precision rounding, so somewhere somebody is casting the number to single. Bekhof code?
VCO frequency is about 80MHz, and 8e7=(1+fractional)*2^26 (fractional is about 0.1921, but that's not important).
Single precision number uses 23 bits for fractional. For any number in [2^26, 2^27) range, the least significant bit is 2^-23 * 2^26 = 8.
EPICS values are fine, so this is a problem of DAQ/NDS/DV.
Channels are double-precision in the front end, but stored as single-precision in the frames. Maybe Jordan was getting this data from the frames/NDS2, rather than live, so that's why there's this quantization error?
