Following on from last week’s update: our pre-storm planned maintenance downtime officially began on Monday, September 14. We are still off-sky; here is where things stand as of September 18.
Power. The site remains on 24/7 generator power, with the 750 kVA unit carrying the load and a rented backup standing by. The rental was commissioned this week and automatic failover from the main generator was confirmed, so the backup will now pick up without anyone intervening. An electrical crew is on-site around the clock until the observatory is back on sky. Further power mitigations and repairs are in progress, with a focus on transient suppression at the auxiliary telescope and repair of the 1 MW generator, which is targeted for later this month. Restoring commercial power, however, is a longer-term project; planning is well underway, and it will not block our return to night observing.
Cooling and camera systems. The camera refrigeration maintenance that set the timing of this downtime is going well. Refrigerant was recovered from four circuits and flushing is now complete on two of them. Glycol chiller work is continuing alongside planned improvements and maintenance, with Dynalene work starting next week. The team expects next week to mark full restoration of the observatory-wide cooling arrangement the site had before the storm.
Communications and computing. LSSTCam’s servers were powered back on this week, and the control room and clean room were both energized. Clean-room air handling is running again with particle counters, so the room can be confirmed clean before the camera team needs it. Bringing up the rest of the summit data center servers is the pacing item for restoration of the control systems.
Dome and mechanical work. The dome team continued pre-assembly of the final two light/wind screen (LWS) panels on the maintenance floor, as well as preparations for further louver control and LWS panel installation. Fabrication of the oil-tray covers for the telescope azimuth bearing system is in its final stages, and the work has widened to include the elevation system, with installation starting in earnest after the holiday.
What’s next. Thursday and Friday are Fiestas Patrias in Chile, so there will be little activity on the summit over the long weekend. Work resumes on Monday, September 21, with a full week ahead: CO2 mirror cleaning, recovery of the observatory control systems, dome rotation, oil-tray installation, LSSTCam maintenance, an in-situ mirror wash component fit-check, and cooling system maintenance. With a schedule this full, we do not yet have a return-to-sky date to announce.
Thanks again to the teams on the summit and in La Serena, working through the recovery and the annual maintenance at the same time.