Mode is ETMY 32761.5 Hz.

First attachment shows the mode as seen in H1:OMC-PI_DCPD_64KHZ_AHF_DQ while rung up before the first lockloss ~7 UTC today. Second attachment shows that this mode (in black) is from ETMY by following other known ETMY modes (in blue) during the 19 hr lock that ended in that lockloss. We see that it is indeed at 32761.5 Hz - as opposed to aliased down from 32775.5 Hz - since it follows the slope of the ETMY drumhead and 15kHz mode, contrary to the 18kHz mode which is aliased down from 47kHz and thus is seen to move opposite.

I will set up damping asap - it will drop us out of Observe and since we are currently in coincident time, I'll wait until one site drops or the mode starts to ring up. Currently monitoring.

Sheila, Terra

There's 4 modes in this 32.76kHz region, two on each end test mass: 32761.5 Hz ETMY, 32764.5 Hz ETMX, 32766 Hz ETMX, 32767.5 (aliased down from 32768.5) Hz. ETMY, as shown here.

The first and last have sat the highest over the past several locks (the first breaking a few locks), so we've set up damping loops for them:

MODE 23: 32761.5 Hz ETMY and MODE 22: 32767.5 Hz ETMY

Note that the Nyquist is 32768 Hz, so MODE 22 sits right there on it and none of this region can be seen in DTT (something something it cuts off before the Nyquist?). They can be seen in the OMC-PI channel and they've been added to the PI2 StripTool. Have added all 4 to PI Wiki.

Mode 22 and 23 are set up to damp on ETMY. both using channel 5 on ETMY.  Both 22 and 23 are on the PI2 stip tool, but niether is added to verbal alarms yet so operators will want to keep an eye on the StripTool this weekend.  

The damping gains and phases for these modes are unmonitored in SDF.  If you see one of the modes ringing up, try damping it.  Since we don't know what shape these modes have, Terra suggested that we try damping it with the same sign on UR and LL.  If this isn't working, you can try flipping the matrix element for LL to -1, see the attached screenshot for how to do that. 

Raised CP3 LLCV to 15%.

Kyle fixed CP4 actuator by melting the ice and draining the water (pulled the fuse which killed autofill 19 min. into operation), and tightened the elbow seal. Manual fill took 41 min. with 1/2 turn on bypass valve, in addition to 19 min. of autofilling at 70% open on LLCV. Raised LLCV from 39% to 42% open.

    I added the new modes 19 and 20 to the PI2_monitoring.stp StripTool. The nuc6 screen has been reloaded with the new modes.   

The CBC wiki page has been moved to https://www.lsc-group.phys.uwm.edu/ligovirgo/cbcnote/PyCBC/O2SearchSchedule/O2Analysis2LoudTriggers/PSLblips

I ran PCAT on H1:GDS-CALIB_STRAIN and H1:PSL-ISS_PDA_REL_OUT_DQ from November 30, 2016 to December 31, 2016 with a relatively high threshold (results here: https://ldas-jobs.ligo-wa.caltech.edu/~cavaglia/pcat-multi/PSL_2016-11-30_2016-12-31.html). Then I looked at the coincidence between the two channels. The list of coincident triggers is:

-----------------------------------------------------
List of triggers common to PSL Type 1 and GDS Type 1:
#1:	1164908667.377000

List of triggers common to PSL Type 1 and GDS Type 10:
#1:	1164895965.198000
#2:	1164908666.479000

List of triggers common to PSL Type 1 and GDS Type 2:
#1:	1164882018.545000

List of triggers common to PSL Type 1 and GDS Type 4:
#1:	1164895924.827000
#2:	1164895925.031000
#3:	1164895925.133000
#4:	1164895931.640000
#5:	1164895931.718000
#6:	1164895958.491000
#7:	1164895958.593000
#8:	1164895965.097000
#9:	1164908667.193000
#10:	1164908667.295000
#11:	1164908673.289000
#12:	1164908721.587000
#13:	1164908722.198000
#14:	1164908722.300000
#15:	1164908722.435000

List of triggers common to PSL Type 1 and GDS Type 7:
#1:	1166374569.625000
#2:	1166374569.993000

List of triggers common to PSL Type 1 and GDS Type 8:
#1:	1166483271.312000

-----------------------------------------------------

I followed-up with omega scans and among the triggers above, only 1164882018.545000 is a blip glitch. The others are ~ 1 sec broadband glitches with frequency between 512 and 1024. A few scans are attached to the report.

Hi Marco,

your 'List of triggers common to PSL Type 1 and GDS Type 4' (15 times in two groups) are all during the known times of telephone audio disturbance on Dec 4 - see https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=32503 and https://www.lsc-group.phys.uwm.edu/ligovirgo/cbcnote/PyCBC/O2SearchSchedule/O2Analysis2LoudTriggers/PSLGlitches

I think these don't require looking into any further, the other classes may tell us more.

The GDS glitches that look like blips in the time series seem to be type 2, 7, and 8. You did indeed find that the group of common glitches PSL - GDS type 2 is a blip glitch. However, the PSL glitches in the groups with GDS type 7 and 8 do not look like blips in the omega scan. The subset we identified clearly shows blip glitch morphology in the omega scan for the PSL channel, so it is not surprising that those two groups turned out not to be blips in GDS.

It is though surprising that you only found one time with a coincident blip in both channels, when we identified several more times in just one week of data from the omicron triggers. What was the "relatively high threshold" you used?

Hi. Sorry for taking so long with this. I rerun PCAT on the PSL and GDS channels between 2016-11-30 and 2016-12-31 with a lower threshold for glitch identification (glitches with amplitude > 4 sigma the noise floor) and with a larger coincidence window (coincident glitches within 0.1 seconds). The list of found coincident glitches is attached to the report. Four glitches in Miriam's list [https://www.atlas.aei.uni-hannover.de/~miriam.cabero/LSC/blips/O2_PSLblips.txt] show up in the list: 1164532915.0 (type 1 PSL/type 3 GDS), 1164741925.6 (type 1 PSL/type 1 GDS), 1164876857.0 (type 8 PSL/type 1 GDS), 1164882018.5 (type 1 PSL/type 8 GDS). I looked at other glitches in these types and found only one additional blip at 1166374567.1 (type 1 PSL/type 1 GDS) out of 9 additional coincident glitches. The typical waveforms of the GDS glitches show that the blip type(s) in GDS are type 1 and/or type 8. There are 1998 (type 1) and 830 (type 8) glitches in these classes. I looked at a few examples in cat 8 and indeed found several blip glitches which are not coincident with any glitch in the PSL channel. I would conclude that PCAT does not produce much evidence for a strong correlation of blip glitches in GDS and PSL. If there is, PSL-coincident glitches must be a small subset of blip glitches in h(t). However, some blips *are* coincident with glitches in the PSL, so looking more into this may be a good idea.

Hi,

thanks Marco for looking into this. We already expected that it was a small sub-set of blip glitches, because we only found very few of them and we knew the total number of blip glitches was much higher. However, I believe that not all blip glitches have the same origin and that it is important to identify sub-sets, even if small, to possibly fix whatever could be fixed.

I have extended the wiki page https://www.lsc-group.phys.uwm.edu/ligovirgo/cbcnote/PyCBC/O2SearchSchedule/O2Analysis2LoudTriggers/PSLblips and the list of times https://www.atlas.aei.uni-hannover.de/~miriam.cabero/LSC/blips/O2_PSLblips.txt up to yesterday. It is interesting to see that I did not identify any PSL blips in, e.g., Jan 20 to Jan 30, but that they come back more often after Feb 9. Unfortunately, it is not easy to automatically identify the PSL blips: the criteria I used for the omicron triggers (SNR > 30, central frequency ~few hundred Hz) do not always yield to blips but also to things like https://ldvw.ligo.caltech.edu/ldvw/view?act=getImg&imgId=156436, which also affects CALIB_STRAIN but not in the form of blip glitches.

None of the times I added up to December appear in your list of coincident glitches, but that could be because their SNR in PSL is not very high and they only leave a very small imprint in CALIB_STRAIN compared with the ones from November. In January and February there are several louder ones with bigger effect on CALIB_STRAIN though.

The most recent iteration of PSL-ISS flag generation showed three relatively loud glitch times:
https://ldas-jobs.ligo-wa.caltech.edu/~detchar/hveto/day/20170210/latest/scans/1170732596.35/

https://ldas-jobs.ligo-wa.caltech.edu/~detchar/hveto/day/20170210/latest/scans/1170745979.41/

https://ldas-jobs.ligo-wa.caltech.edu/~detchar/hveto/day/20170212/latest/scans/1170950466.83/

The first 2 are both on Feb 10, in fact a PSL-ISS channel was picked by Hveto on that day (https://ldas-jobs.ligo-wa.caltech.edu/~detchar/hveto/day/20170210/latest/#hveto-round-8) though not very high significance.
PSL not yet glitch-free?

Indeed PSL is not yet glitch free, as I already pointed out in my comment from last week.

Imene Belahcene, Florent Robinet

At LHO, a simple command line works well at printing PSL blip glitches:

source ~detchar/opt/virgosoft/environment.sh
omicron-print channel=H1:PSL-ISS_PDA_REL_OUT_DQ gps-start=1164500000 gps-end=1167500000 snr-min=30 freq-max=500 print-q=1 print-duration=1 print-bandwidth=1 | awk '$5==5.08&&$2<2{print}' 

GPS times must be adjusted to your needs.

This command line returns a few GPS times not contained in Miriam's blip list: must check that they are actual blips.

The PSL has different types of glitches that match those requirements. When I look at the Omicron triggers, I do indeed check that they are blip glitches before adding the times to my list. Therefore it is perfectly consistent that you find GPS times with those characteristics that are not in my list. However, feel free to check again if you want/have time. Of course I am not error-free :)

I believe the command I posted above is an almost-perfect way to retrieve a pure sample of PSL blip glitches. The key is to only print low-Q Omicron triggers.

For example, GPS=1165434378.2129 is a PSL blip glitch and it is not in Miriam's list.

There is nothing special about what you call a blip glitch: any broadband and short-duration (hence low-Q) glitch will produce the rain-drop shape in a time-frequency map. This is due to the intrinsic tiling structure of Omicron/Omega.

Next time I update the list (probably some time this week) I will check the GPS times given by the command line you suggest (it would be nice if it does indeed work perfectly at finding only these glitches, then we'd have an automated PSL blips finder!)