Skipped initial alignment. Worked ok, not sure if it saved time, I had to do quite a bit of by-hand alignment during lock acquisition.
Sheila previously suggested the ALS Y arm glitches show up when it is raining. I noticed that this afternoon ALS Y arm glitches were frequent, and it was raining. Now the y-arm glitches are gone and it is not raining. Coincidence?
Had 45 mins of NLN with no glitches, 1232065259 - 1232057789. Later in the same lock a ~50Hz scatter-looking lump showed up. First attached figure is DARM BLRMS as the lump first showed up, with excess noise in the red BLRMS progressively gets worse. The second attached figure is a spectrogram for a period later in the lock, also showing line at 46.1 Hz line that drifts in and out of the spectrum.
Moved ads dither lines (PIT3, YAW3, YAW5), implemented in guardian. The gains and phases of these loops will likely need further fine tuning in the future, so far we've successfully acquired and powered up with the new lines. In a later lock I had problems engaging the other dither loops due to a low frequency ring up. I reduced the gain of the dither loops during acquisition, and re-increased the gain in the INCREASE_POWER state so we don't spend too much time waiting for things to converge.
Had several locklosses from ENGAGE_ASC_FOR_FULL_IFO, where SRC1, SRC2, PRC1, PRC2 yaw ran away after increasing the PRC1, PRC2 and SRC1 gains. Made the convergence checker for PRC2 and SRC2 stricter and increased wait times, PRC2 is especially slow to converge.
Craig plugged in the SR785 by the PSL racks to take CARM transfer functions, this made the 120 Hz line worse, and in the next two locks we had broadband noise DARM that was coherent with excess noise also visible in SRCL and PRCL. In one lock the noise was at ~750 Hz, and the next from ~80-400 Hz. We went out to unplug the SR785 through the main door to the LVEA and lost lock when tip toeing past HAM2. In the next lock, with the SR785 unplugged, the noise was gone. We went back into the LVEA to plug the SR785 back in, this time through the back door, and again lost lock while tiptoeing past IOT2L.
Picture of SR785 coupling to SRCL, PRCL, MICH, and DARM, but curiously not CARM. The SR785 was plugged into TEST1, TEST2, and EXC A of the common mode board. The PSL ground loop is somehow strongly coupling to the POP error signals, particularly POP9. The mechanism of this coupling is still unclear. I've plugged the SR785 back in for more CARM loop measurements, and the increased broadband noise is not here as of now.
