[Sheila, Jenne, Kiwamu, Terra]

We have reset the initial alignment offsets, including realigning several paths on ISCT1, to match the alignment that we liked from yesterday (alog 29430).  So far, we think that it's good.  We have powered up part way twice since, and the power recycling gain no longer drops very much!  It still drops a bit, so we could consider going a bit farther, but this is probably plenty good to move on and focus entirely on low noise efforts.  Now at 40W it is something like 31, rather than something in the mid/low twenties.  Plots coming tomorrow.

In order to do this, we did the following (hardware alignment changes noted in bold):

• Lock using old alignment, at DC Readout move most of the way to the new alignment using PR2 sliders and POP_A offsets.
• Relieve the POP_X centering loop PZT on ISCT1 by *very slowly* moving the knobs on the steering mirror that goes to POP_X.  We were able to do this while locked, and PRC2 was using POP_X in-loop. 
• We then tried to power up with the new alignment to ensure that it was good.  It seemed pretty good (PRC gain stayed roughly constant), but we lost lock due to dPdTheta. 
• For our next lock, we had to lower the threshold at which the POP_X centering loop triggers on, since the beam was partly off the WFS.  (spoiler alert: once we finished all alignment work for the night, this is no longer necessary.  POPX is already quite centered before the centering loop comes on.)
• Once we were relocked with our PR2 slider motion and POPA offsets in place, we set the green input pointing QPD offsets such that the green beams were maximally co-aligned with the IR in the arms, and the green WFS signals were all zero.  This was done at DC Readout, 2W.  We also reset the green ITM camera setpoints.
  • We lost lock while doing this, but the Yarm was already complete.  Sheila did a test InitialAlignment of just the green Yarm and saw that the test masses didn't move according to their oplevs from where we wanted them by more than a few tenths of a microradian.
  • For the Xarm, we put the test masses back to the locations that the oplevs said they wanted to be from the 2W DC Readout lock, and then finished setting the QPD and camera offsets.  The test masses had to be moved by several microradians each in both pitch and yaw to get the unlocked mirrors pointed the same way that they were while being controlled by the ASC loops.
• We centered the green beams on ISCT1 on the green transmission PDs and on the transmission cameras.
• We put PR3 and BS back to the places that their oplevs said they were during our 2W DC Readout lock, then aligned both the ALS Comm and ALS Diff beatnote PDs.
• TJ did an initial alignment for us using the new set points.
• We aligned POPAIR_A and POPAIR_B, although neither was very far off.
• We checked that the DRMI ASC works using the POP_A offsets that we like.  This is now in the guardian, but at some point we should picomotor to recenter POPA in this new place.
  • PRC1 and SRC1 and SRC2 are once again turned on in the DRMI ASC guardian.
  • This makes CHARD come on much more nicely (although we have still had a few locklosses trying to engage these loops).  The gain has been redistributed in the guardian so it also comes on more slowly, but it's apparently still not perfect yet.  At least engaging CHARD makes the recycling gain go up rather than down, which it had been doing until this afternoon (the recycling gain would come back once the PRC1 loop was closed around POPA).
• On our first power up with the new alignment, we lost lock due to the dPdTheta instability.  Kiwamu measured the suppression at the resonance frequency, and increased the gain of the ISS 3rd loop by a factor of 3.
  • Upon our next power up, it seems as though we can't increase the power quite as fast, without causing trouble.  Tomorrow we will try with the ISS 3rd loop gain only up by a factor of 2, and we will also try increasing the power more slowly.
  • Sheila tweaked the CSOFT pitch loop shape so that we no longer have a marginally stable point around 0.45 Hz - this will allow us to increase the gain such that we can help hold against the instability.
• On our next power up, we lost lock with an ISS saturation.  We think this is due to the 3rd loop gain being too high / increasing the power too fast.
• A few minutes later, the PSL shut off.  Commissioning to be continued tomorrow when more photons are available.