The attached plot is rather busy with traces, but it's a summary of the present performance of the ISS second loop.

In brief, the second loop is behaving well: the intensity noise is well within specifications above 30 Hz. If you're interested, more details follow.

The blue, red and green solid thin traces are measurements taken this morning. The blue one shows the intensity noise at the ISS box when the second loop is open. The green and red traces show the in-loop and out-of-loop intensity noise with the second loop closed. The light green dashed trace shows the expected level of out-of-loop noise assuming to be shot noise limited, for a total of 20 mW entering the array (which is what we're measuring right now). We see that the out-of-loop performances are very well explained by shot noise between 70 and 200 Hz. Above 300 Hz we are gain limited, so the suppression is not enough to go down to the shot noise level.

The other dashed traces show the intensity noise requirements. The black dashed curve is taken from the design document T1100265-v1. The other curves are the result of simulations with MIST: radiation pressure is included, SRC is in broad-band configuration, no asymmetry is introduced in the interferometer. The latter point is particularly important, since LLO experience and simulations showed that the coupling of intensity noise can increase a lot if we have IFO asymmetries, like lenses in the ITMs. However, at LLO a reduction of RIN coupling down to the ideal model has been demonstrated using TCS. The two curves corresponds to 125 W and 25 W in input. The IFO sensitivites are taken from here.

In summary, the present performance of the ISS is good enough to meet the requirements above 20 Hz for operations at 25 W. If we could fix the structures between 10 and 20 Hz, we would be ok at all frequencies. Clearly, this is the intensity noise measured at the ISS level, so far there is no guarantee that the same good level of intensity noise is maintained into the IFO. We'll have to take a look into that.

This morning, while the MC was unlocked, I zeroed the offsets of WFS_A and WFS_B. I wanted to check if they were responsible for the IMC angular offsets I added recently.

The answer seems to be negative. I had tom retuned the IMC DOF offsets, but the optimal values are still not zero:

evan, nic, sheila

The temperature at EY was stable for most of the last month to within ~0.5 deg C until the last few days. Recently there were excursions of as big as 3 deg C. We think this is responsible for TMS misalignments.

model restarts logged for Tue 11/Nov/2014
2014_11_11 01:42 h1fw0
2014_11_11 10:27 h1fw1
2014_11_11 12:23 h1broadcast0
2014_11_11 12:23 h1dc0
2014_11_11 12:23 h1fw0
2014_11_11 12:23 h1fw1
2014_11_11 12:23 h1nds0
2014_11_11 12:23 h1nds1
2014_11_11 20:50 h1pslpmc
2014_11_11 20:52 h1ioppsl0
2014_11_11 21:11 h1ioppsl0
2014_11_11 21:14 h1pslpmc
2014_11_11 21:17 h1ioppsl0
2014_11_11 21:17 h1psldbb
2014_11_11 21:17 h1pslfss
2014_11_11 21:17 h1psliss
2014_11_11 21:17 h1pslpmc
2014_11_11 21:49 h1ioppsl0
2014_11_11 21:49 h1psldbb
2014_11_11 21:49 h1pslfss
2014_11_11 21:49 h1psliss
2014_11_11 21:49 h1pslpmc

Two unexpected restarts. Tuesday maintenance. Multiple restarts of Beckhoff chassis (not shown) with associated DAQ restart. Restart of h1psl0 models as part of investigation into PSL issues in CER.

See the attached for a look at these very conservative 2Hz controllers.  The correct matrices will have to be installed before these will work.  I'll put these in when Keita says okay or on Tuesday Maintenance day which I expect are the same!

K. Venkateswara, J. Warner

The BRS damper (see 14388)  has been malfunctioning since yesterday afternoon. It's controller is an open loop system that assumes it is in the centered position when it is first started. Occasionally it can get restarted accidentally when the insulation box is bumped (probably due to a short somewhere, but I'm not sure where). It looks like this happened yesterday around noon.

This requires a manual re-centering of the turn-table for the feedback system to work as designed. I've attached the directions to do this. Jim will do this later today or tomorrow.

I have started to tar and compress older autoburt snapshot files to free up disk space - the snapshots saved so far consume over 1TB on disk, which is about 25% of the capacity of the /ligo filesystem.  Currently the plan is to retain roughly the last three months of data in it's uncompressed form, with data older than that retained on disk in a compressed tar archive only.  Files will be archived by month (so all of the files from a given month will be in a single tarball).  Since the snapshot files are all ASCII text, they should compress down well.  This should also speed up the rsync backups, since there will no longer be 2.8 million files to traverse looking for changes.  If you need assistance accessing older snapshot files stored in the tar archives, please see one of the CDS admins.

Something happened at about 10:30PM (11-12-2014 6:30 UTC) and the 363Hz oscillation of the end Y PZT mirror(s?) went totally unstable.

Daniel and Alexa are heading to EY to swap the controller.

In the attached right, references are from 24 hours ago, current traces are as of now. The trend shows the green QPD and the VEA temperature for 3 days.

As I reported in 14965, I suspected WHAM3 ISI OpLev Pitch and Yaw were reveresed as I believe is HAM2's.  See the attach where I yaw'd WHAM3's HEPI.  The HEPI Pitch moves as well but a couple of orders of magnitude less.  Likewise on the OpLev, the Pitch responds much more than the Yaw, so yes,

HAM3 ISI OpLev Pitch & Yaw are Reversed

The chilled water temperature at MIDY alarmed HIGH this morning. There is no demand for cooling so the water is bypassing the cooling coils completely and therefore the water pump is only heating the water.

I have turned both mid station pumps off.

This cold front has sent our temperature control loops out of whack - Last night I turned on heaters in both end stations. Today we will monitor and perhaps turn on more heat in both the LVEA and the end stations.

Alexa, Evan, Nic, Sheila

We seem to have lost the -24 V rail and the -12 V on several racks in the electronics room.  The PSL/IO/TCS beckhoff chassis power switch was in the off position when we went out there, I tried flipping it to on and the rocker switched off again immediately.  On the cds overview we have lots of red on the PSL frontends, this chassis is in the same rack as the PSL/IO/TCS beckhoff chassis, and they are on the same 24 V supply.  Nic restarted the front end models several times, then restarted the computer, then restarted the computer and restarted the PCIE expansion box.  (before we realized that we were missing power). 

(Alexa, Sheila, Evan)

As we were trying to lock ALS DIFF, we noticed that both the COMM and DIFF beatnote were too weak. We trended these values and found that the beatnote first disappeared when the PSL went down and then again at around 9am PST. I then tried locking the IR to the x-arm and found that I had to move PR3 by 4 urad in pitch to lock. The input wfs then moved IM4 and PR2 to increase the buildup.  We suspect things got moved around again with the work and trips on HAM2, HAM3. We didn't spend too much time investigating the exact cause, and we did not want to go through the entire alignment to lock DRMI and check the POP18 counts since we want to focus on DIFF right now. Hopefully we didn't introduce a new clipping in the PR2 baffle by the amount we moved. 

IMPORTANT: I have not saved these new alignment values, so if the guardians get realigned they will restore the old alignment values.

Also, the beam in the AS AIR camera looks too far to the right.

Gerardo & Hugh

We recentered these oplevs to make better use of their tracking.  And especially HAM2 as it seemed to be way off on one quadrant.  Luckily we didn't lose the beams.

First attached is a three day trend showing yesterdays fun with HAM2 and the recentering this morning.

Next is the last eighty minutes, maybe given the wandering, the X-Y plots on the medm should have their window zoomed out some.  This seems to be an issue mostly on HAM3 Yaw.

The third plot shows the five hour detail around yesterday morning on HAM2 with the HEPI Cartesian RZ (yaw) RY (pitch) and HP, the horizontal pringle mode.  This further shows even though the HEPI RZ has servo'd back to its reference, the OpLev Yaw would disagree.  Likewise, even though the HEPI pitch shifted way off for most of the time and then came almost all the way back, the OpLev Pitch doesn't follow that in any reasonable way.  Even though these OpLevs have no caibration as I understand, this says alot about system distortion.  I've included a feducial from the large shift in the HP calculation but it doesn't appear to correlate to anything in the OpLev response.