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

Possibly due to a wind gust that reached almost 40 mph.

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 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.

Attached are 45 day trends of the pressure out from the pumps and the control drive to the motor.  After seeing the dips very evident in the End control drives, I replaced the CS pump output for 1 2 & 3, which are as flat as PS4, with the outside air temp.  Very clear, the change in temp drives the pumps' need for speed.

Still much noisier than the others but the EX pressure cleaned itself up for some unknown reason a week ago...

And like clock work, the EndY daily and weekly glitches are still present.  Anybody?

Jenne, Sheila, EvanH, Hugh

We had a fortuitous rapid drop in the wind speeds around 1400pdt and while not attempting to lock, it was a quick study looking at the GS13 signal while changing the blends to see that the 45 mHz were much quieter.  Of course there still is the worry about the ETMX X 45 blend ringing up MCF but we decided that if it does,maybe we can study it or try something.

The blend switch, and why we though it was a good idea given the reduced winds ad the very elevated microseism is clearly seen on the attached plot.

It still took some time to lock, maybe still a little much wind or something else.  Still we decided to not switch the ETMX X blend back fearing that it woould likely break the lock.  So for over an hour we've only had minor flare ups of MCF but it really hasn't grown and faded after just a couple cycles.

TITLE:    Dec 9 DAY Shift 16:00-00:00UTC (08:00-16:00 PDT), all times posted in UTC

STATE Of H1: Observing

SUPPORT: Sheila, Hugh, TJ, Jenne, Robert and Jordan

LOCK DURATION: 36min

INCOMING OPERATOR: Nutsinee

SHIFT SUMMARY:

• A combination of high microseism and high winds, for most of the day, made it less than possible for locking.

• Twice today the call for doing maintenance was made.

• Hugh and Sheila were able to determine the best blends to use at the End Stations for locking today.

• Sheila, Jordan and Robert tweaked the COMM VCO to get rid of some unwanted lines in DARM

• DRMI Lock was finally achieved at 23:02UTC

• Intention Bit set to Undisturbed at 23:50UTC

• There is a timing error showing in the ETMX CDS overview that got forgotten. It can be reset in the case of lockloss.

ACTIVITY LOG:

16:15  Fil out to LVEA to do some more cable pulling

16:25 Jeff Bartlett and Mitch out to LVEA to do some more work on dust monitor plumbing

16:30  Peter into LDR

16:40  Peter out of LDR

17:01  Jeff and Mitch out of LVEA

17:03  Jeff and Mitch to EX

17:21 Richard called to let me and Mike know that he has started his work in the CER.

17:40  Gerardo out to Y-2-8 to refuel the generator

17:54  Richard, et al, are finished in the CER and are heading down to EY.

18:19 Bubba heading to MX to work on a fan.

18:39 Gerardo back from Y-2-8

21:22  Kyle to Y-2-8 to take some temp readings

21:55 Kyle back to corner station

23:21  H1 is locked at Nominal Low Noise!

23:50  Intention Bit set to UNDISTURBED

23:50UTC

TJ & Hugh

With IFO down from elevated winds, we attempted to have the Guardian switch the gains more like how the old SEI COMMANDS script switch the gains--WP5647.

Original svn update 24 Nov alog 23695--Change tested on HAM5 and worked.

7 Dec, ISI trips with EQ reveal problem of this switching but only for HAMs 2 & 3, aLOG 24028.

In alog 24054 I report how the GS13 gain switch when done by the guardian well after the platform was isolated and quiet would still trip the HAM3 ISI.  This led us to believe it was not the timing of the guardian GS13 switching--at the end of Isolation process after/while finishing the driving to the reference CPS location; but, that it was more related to how the guardian was doing the switching.  The guardian switches both FM4 & 5 at the same time whereas the COMMAND script switches all the FM4 and then all the FM5s with a 1 sec sleep between.--See SEI Log 894 comment for code comparison.

Today,TJ modified the guardian code, see comment below, to try simulating the way the COMMAND script switches the Gain.  Bottom line it still tripped.

We even tried reversing the order of the FM4 & 5, that is first FM5 then FM4 to turn off the analog whitening before we increased the analog gain, still tripped... So we still scratch our heads, it's winter, my skin is dry and it itches anyway.

Mike Landry has given the final "OK" to proceed with maintenance tasks this morning due to the IFO being down due to high winds. Livingston has been contacted regarding our plan. They are currently back "UP".

O1 days 81,82

model restarts logged for Tue 08/Dec/2015
2015_12_08 11:51 h1broadcast0

Maintenance day, DMT channel added to broadcaster

model restarts logged for Mon 07/Dec/2015

No restarts reported

TITLE: Dec 9 DAY Shift 08:00-1t6:00UTC (00:00-08:00 PDT), all times posted in UTC

STATE Of H1: Environment

OUTGOING OPERATOR: Patrick

QUICK SUMMARY: Doesn’t look like a good day for locking unless the wind dies back significantly.

TITLE: 12/09 [OWL Shift]: 08:00-16:00 UTC (00:00-08:00 PDT), all times posted in UTC

STATE Of H1: Unlocked
SHIFT SUMMARY: Lock loss likely from earthquake. High winds and microseism have hindered relocking ALS. Tried different combinations of ISI blends to no avail. The Y arm has been the least stable.
There is a timing error on H1SUSETMX.
INCOMING OPERATOR: Ed
ACTIVITY LOG:

10:41 UTC Lock loss. Arms not staying locked on green. Put ISC_LOCK guardian to DOWN to wait out earthquake. Adjusted REF_SIGNAL to increase ISS diffracted power.
13:38 UTC Started attempting to relock
15:33 UTC Bubba driving down arms to assess tumbleweed buildup

In checking on the reference cavity transmission this morning, I noted that it took a
dive over the last day in particular, and over the last three days in general.  Also
attached is a plot of the IMC locked status.

Looking over the trend data, it appears to me that the reference cavity transmission
suffers when there are long periods of time when the IMC is trying to acquire lock.
My hypothesis is that the IMC trying to acquire lock means that the VCO frequency of
the double-passed AOM swings from one extreme to the other.  This might result in
heating of the AOM, which in turn changes the alignment of the AOM with respect to
the input beam.  We don't observe an alignment change on the nearby EOM because the
EOM is too close for a small alignment change to be noticed.  Of course we observe
the alignment change on the iris located in front of the reference cavity, since that's
some distance away from the AOM (~2 m).

Also attached is a plot of the reference cavity transmission and VCO frequency.

One might ask, why didn't you just fix it by re-aligning the AOM previously.  And the
convenient answer is that the AOM alignment is quite sensitive.  This doesn't necessarily
fix the problem if overheating of the AOM is the culprit.

Mike L. called and notified me that there was a SNEWS test alert entered into GraceDB (E206974, see attached screenshot). I did not get a verbal alarm.

Evan Hall suggested changing ETMY ISI blend filters after a couple lock losses between DRMI and ENGAGE_ASC.

The change from all Quiet_90s to Quiet_90 in X direction, and 45mHz in Y direction was easilly seen on ST1_ISO_RX and ST2_ISO_Y, and the ASC control signal in pitch being sent to the optic, ASC-ETMY_PIT_OUTPUT.

Plot attached shows those channels before and after the blend filter change, and ETMX ASC control signal, to compare.

Current blend filter config. medm is also attached.