J. Jones,  J. Kissel, P. Thomas

Some notes on recovery today:
- After lock loss for unknown reasons at 2019-08-27 14:38 UTC (see LHO aLOG 51536), we proceeded with maintenance day as planned. Note, several plans involved using the IFO during maintenance (i.e. it would stay up in to maintenance period, and maintenance/commissioning would be performed with the full IFO), but could not proceed due to the unknown lock loss.

- As usual, ground motion sensor correction for the seismic isolation systems (which includes input from BRS) was turned off site wide, as a is normal practice to avoid the cleaning crew and others impacting chamber motion by ringing up/exciting ground sensors.

- The following *unplanned* things happened:
    (a) Early in the morning, H1 ETMX HEPI Pump Tripped. Took a long time to recover, sucking up ETMX from use with the IFO, slowing recovery.
    (b) Mid-morning, TCSY laser tripped. Short time to recover, did not impact recovery.
    (c) Mid-morning, planned activity on BRS EY went south [only diagnosably so by late morning], needed further adjustment late in the morning

- The recovery began at 18:43 UTC [11:34 PDT], (still with all sensor correction OFF), when activity ceased enough that I could begin Initial alignment in green on Y-ARM (IMC was already up, locked, stable, and running). 
    - I knew that gym was done with his BRS work at EY, and that initial alignment of the green arms takes ~10-20 minutes, so I wanted to launch at least some of the long poles. At this point, we still didn't have end-X.
    - Instead of engaging the automated initial alignment system as per normal, I
        - took the ISC_LOCK guardian to INITIAL_ALIGNMENT, which used ALIGN_IFO to begin configuring the IFO for initial alignment, and triggered the start of the INIT_ALIGN automatic initial alignment sequence.
        - HOWEVER, I think switch the INIT_ALIGN guardian to AUTO, so I was the manager, and held it on PREP_FOR_GREEN, let it finish, then brought the ALS_YARM guardian (normally managed by INIT_ALIGN) to INITIAL_ALIGNMENT.
        - Didn't work, because (i) the arm motion was a little too high, and (b) the alignment of the ETM / TMS was such that the flashes were too low.
        - Requested ALS_YARM to UNLOCKED, manually touched up the alignment of ETM/TMS to get green flashes high,
        - Re-requested ALS_YARM to INITIAL_ALIGNMENT, and with success held there, in holding pattern waiting for ETMX to be recovered.

- 19:52 UTC 
    - Hugh, Jeff B and Richard M recovered HEPI operation with a temporary solution (i.e. fixed (a) from above), and brought ETMX seismic platform back to nominal configuration. 
    - Also configured site-wide system sensory correction "ON", except for BRS Y, which is still off.
    - Began initial alignment of X-arm with some confusion about how to bring INIT_ALIGN guardian to the right state vs. management of ALS_XARM, ended up requesting INITIAL_ALIGNMENT_COMPLETE, which essentially restarted everything and lost progress on Y-ARM. Should have requested "GREEN_ARMS_OFFLOADED" from ALS_YARM before pushing forward with the INIT_ALIGN guardian.
   
- 20:19 UTC 
    - Both green arms aligned and offloaded. On the rest of initial alignment (which no longer needed the arms), thus
    - Launched Jim traveling to EY to continue addressing EY BRS (i.e. (c) from above)
    - brought site-wide observatory sensor correction configuration to WINDY_NOBRSY (i.e. nominal for everyone but ETMY, which could not yet use the currently non-functional BRS EY). Jim manually further modified that end station's sensor correction configuration
    
- 20:35 UTC
    - Problems with MICH_BRIGHT, in that repeated attempts to lock flip-flopped (as it should) ALIGN_IFO between MICH_BRIGHT_LOCKED and DOWN in order to stop oscillations of MICH_BRIGHT. Tried holding in DOWN, touching up the beam splitter in pitch using AS_B and the AS camera as my metric, re-requesting MICH_BRIGHT_LOCKED and the oscillations continued.... 

- 20:40 UTC
    - .... until they didn't. Problem resolved itself. Jenne suspects that there is still tuning to do with optical lever damping that wasn't coded up in guardian after last week's commissioning of the same issue (see LHO aLOG 51409)

- 20:46 UTC
    - Rest of initial alignment went automatically and completely.

- 21:48 UTC
    - Back to NOMINAL_LOW_NOISE -- once back on the normal lock acquisition sequence, post-initial alignment, the acquisition sequence was entire automatic, save for one Patrick flip (instead of automated flip) from DRMI lock acquisition to PRMI acquisition.

(Went into commissioning PRCL Feed-Forward activity instead of directly in to observing. During that commissioning, Jim deemed BRS EY fixed, and we re-engaged it by requesting site-wide sensor correction configuration to WINDY).

Total time between lockloss and regaining NOMINAL_LOW_NOISE: 7.17 hours.
Total time between recovery start and finish: 3.08 hours.
Delay due to unplanned FAULTS (all on HEPI EX): 1.15 hours.
Issues that impacted recovery time as a result of planned Maintenance Day activity: None (-ish***). 

(***You could claim that the extra BRS EY activity "impacted" recovery, but really not, since we were able dis-engage it from forward progress and parallelize its recovery and the lock acquisition sequence).