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Attending: Nancy Chanover (NMSU), Aleksandr Mosenkov (BYU), Misty Bentz (GSU), Russet McMillan (APO), Mark Croom (APO), Kevin Schlaufman (JHU), Gordon MacDonald (APO), Joanne Hughes (Seattle U), Mukremin Kilic, (OU), Jamey Eriksen (APO), Adam Kowalski (CU), Ben Williams (UW), Anne Verbiscer (UVa), Derek Buzasi (FGCU)

We started by introducing Mark Croom, our new part-time Observing Specialist. Mark is an upper level Astronomy graduate student at NMSU and spent the majority of his career as an aerospace engineer at NASA Langley Research Center before pursuing his passion for astronomy. Although he has been a long-time user of the 3.5m at APO, he began his training as a 3.5m obs-spec in January 2024. We look forward to working with him!

• NMSU - nothing to report
• Colorado - nothing to report
• Wyoming - no report
• BYU - nothing to report
• Washington - Eric sent a report by email with user concerns about time lost due to weather and snow on roof. This will be discussed further - see below.
• Seattle - nothing to report
• NAPG - no report
• JHU - nothing to report, KS has to leave at noon
• UVa - nothing to report, AV has to leave at noon
• Georgia State - nothing to report
• FGCU - nothing to report
• Oklahoma - Muk had questions about mitigation of snow on the roof since some OU users lost clear nights due to this issue. This will be discussed further - see below.

The detailed site report is included below, followed by additional information discussed during today's meeting.

3.5-m Telescope and Instruments Highlights, 12/05/2023 – 2/06/2024

1) Overview

December and January have been wintery at APO. Telescope has continued to work well. Weather has been challenging for observing. A consistent number of snow storms causing lost time for high humidity and snow on the enclosure roof have impacted multiple programs.

Planning is under way for an upcoming visiting instrument team in mid February, and a large class in early March.

2) Operations

3.5m Telescope: Telescope is working well, motion errors seem to be of the seasonal type.

0.5m Telescope: Nothing to report

KOSMOS new slits (high/center/low for both 1.25 and 20 arc-second widths) have arrived and after an initial issue with non captive screws, are ready to use. Vacuum is softening slightly in KOSMOS and it will need a warm up/pump/cool down cycle as soon as the schedule allows it.

ARCTIC diffuser’s rotator service is being planned for later in the spring.

Agile Instrument TEC controls failed. Attempted repairs have been unsuccessful so far.

ARCES had a failure in the fill system which has caused the instrument to start to warm up. Fill system is being repaired and the echelle will be fully warmed, vacuum pumped and cooled as quickly as it can be.

DIS red camera has experienced a failure that is causing all frames to be all the same DN value. Failure is being investigated.

General updates: Jamey thanked to Kevin and other APO users for stopping by the APO booth at the January 2024 AAS meeting; it was nice to meet folks in person after only knowing them through Zoom. The weather at APO has been terrible in December-January. The DSSI team will be here this month, and we are looking ahead to a class visit from CU next month (thanks for CU and OU for being proactive and doing the early planning for their class visits in March and April, respectively). We have been seeing some seasonal motion errors on the 3.5m. The 0.5m has an issue with syncing the time; we are still working on it. The new slits for KOSMOS arrived; after making some small adjustments they are now mounted and available for use.

Snow on the roof issue: The recent winter weather has impacted our ability to open, even during clear nights, due to the accumulation of snow on the enclosure roof. [If we open the enclosure when there is snow on the roof, it will fall down onto the telescope.] There are heaters on the edges of the dome building (not across the top), which we use to help melt the snow. However, the main mechanism for snow removal is sunshine; if it's not sunny – which has been the case after the recent snow storms – the snow on the roof won't melt. Previously we have had staff members go onto the roof while wearing safety harnesses to shovel it off. This raised safety concerns from NMSU's Environmental Health and Safety (EHS) office during their annual safety training. An EHS representative is coming to site soon (their visit last week was postponed due to inclement weather) to inspect and discuss the situation; we may need to modify the hook points used for attaching the people wearing harnesses. We are looking at other options as well, e.g. using long poles to reach the snow, or possibly adding more heaters (but we need to be careful about ruining dome seeing). We recently put in cameras so we can see the snow on the roof and know how much there is. The heaters don't work well at temperatures below -2 C. If we operate them when the temperatures are near freezing then we run the risk of building up ice from the snow melt. This makes it less likely to have snow blowing onto the telescope but more likely to cause damage if that ice falls. This is also why we sometimes have wintertime opening restrictions where the wind speeds must be low. If the winds are below our normal limit but still above that special wintertime/snow limit then we must stay closed, which we recognize is frustrating for users. One person asked if it would be possible to add some sort of structure with sloped sides onto the existing roof? Jamey replied that this would require not only changing the roof but also the doors (to accommodate the additional weight), so it would likely be cost prohibitive. The bottom line is that we recognize that these closures are frustrating for our users, and we are committed to identifying a strategy that can help us remove the snow fairly soon after it falls while ensuring the continued safety of our staff and telescope.

ARCES issue: ARCES had a failure in its autofill system that caused it to warm up, taking it out of service for several weeks. We are pumping it down right now and then will cool it. The earliest possible date that it will return to service is likely around February 16, but it could extend beyond that. The dewar is a big volume to pump down and the cooling will be rather delicate. It has been at least a decade since we have done this in wintertime. We have all of the replacement parts for fill system in hand and they are ready to be installed.

DIS issue: The DIS red channel has had an electronics failure, with all pixels reading the same value. There are no immediate plans to repair it; we have tried every intervention we can do from the outside of the instrument to recover the red camera and not met with any success. We currently don't have the in-house expertise to do an internal repair. This raises the broader issue of when (not if) to decommission DIS. As the oldest instrument on the 3.5m, it continues to show its age and perform sub-optimally. Recall that the acquisition of KOSMOS was intended as a stop-gap measure that would provide continued capability for long-slit optical spectroscopy while Ocotillo is being developed and built. Nearly all former DIS users have migrated to KOSMOS, but there remain a few DIS holdouts. UC reps: please tell your users that we need to understand what capabilities KOSMOS lacks that makes some people still want to use DIS. If it is a resolution issue (either the desire for higher or lower resolution than what is offered by KOSMOS), we still have several slots remaining in the wheel that holds the grisms for KOSMOS. If people want/need different resolution, in principle we could fulfill this need with the addition of one low-res grating that would get the entire spectrum in one shot, and two higher-res gratings. Russet noted that we do now have a complete set of 1.25“ and 20” slits (low, center, and high position) which are better matched to the site seeing, so users can now optimally sample the site seeing. Nancy will follow up with Sarah to get some ROM estimates of costs for additional grisms.

There have been some updates to the Q1 schedule based largely on having to reshuffle time that was scheduled to use ARCES. There is a short OPEN slot available on Feb 18B and a slightly longer one (bright time) on Feb 22A. At this point we cannot guarantee that ARCES will be back in service by that time so we're not sure if we can use those OPEN slots to repay any displaced ARCES users, but anyone who lost time due to weather, telescope or instrument issues is free to request Feb 18B or 22A. There is some additional OPEN and DD time available in March so people can also request some of that.

The Q2 allocation emails were sent to the institutional schedulers, with requests due by February 23. We are expecting that ARCES will be back in operation by Q2, and that DIS red will remain inoperable.

The Q1 schedule for ARCSAT is basically full. There is one week that is listed as unavailable when we will have classes on site. The Q2 call for proposals will be issued in mid-March.

• Jan. 2024 AAS Recap - Thanks to those who participated in booth; it was great to see current and former APO users. Jamey enjoys going to the AAS meetings to represent APO and values making connections with our user community. When Nancy asked the group to consider whether we need to have a presence at EVERY winter AAS meeting, Misty asked what is the motivation for our participation (recruitment for ARC partners? science highlights? job openings/recruitment?). Currently all of our observing time is spoken for between ARC members and lease partners, so it is less about recruitment for ARC and more about showcasing science from the facility and advertising open positions.
• Nancy asked the group to consider one last time the idea of holding an APO 30th anniversary celebration during 2024. We will likely do something to mark the occasion at the ARC Board of Governors meeting in November; the question is whether to do something beyond that (a party? a small science symposium? at APO? dovetailed with the BoG meeting in Chicago? something else?). We discussed a few options but did not reach a consensus.

Open action items from previous meetings:

• None

Open action items from this meeting:

• UC reps: ask your users what capabilities KOSMOS lacks that makes some people still want to use DIS
• Nancy: get ROM costs for new KOSMOS grisms
• UC reps: remind your users to review the Q1 schedule and request OPEN/DD time if they can make a good case for it.

None.

The next meeting will be on March 5 at 10:30 MST.