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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 newest part-time Observing Specialist. Mark is a senior 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-term user of the 3.5m at APO,

• 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, has to leave at noon
• UVa - nothing to report, has to leave at noon
• Georgia State - nothing to report
• FGCU -
• Oklahoma - questions about snow - lost clear nights due to snow on roof - heaters,

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:

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.

Thanks to Kevin for stopping by APO booth at AAS. Weather has been terrible at APO in Dec/Jan. DSSI team here this month, class visit from CU next month - thanks for being proactive and doing early planning. Seasonal motion errors on 3.5m. 0.5m has issue with sync'ing the time - still working on it. KOSMOS - new slits arrived; had to make small adjustment to make them work. ARCES failure in fill system caused it to warm up, pumping down right now, then will cool. DIS red seems to have electronic failure.

SNOW - heaters on edge of dome building, not across the top. Main mechanism for snow removal is the Sun - if it's not sunny, it won't melt. Previously have had staff harnessed up to shovel it off. Raised concern for safety. EHS coming to site this week; may need to modify hook points for harnessed people to hook up to. That was triggered by annual safety training. Looking at trying to use long poles. Examining heaters on edges and weather can add more but need to be careful about ruining dome seeing. Have to be shut off at -2 C . If near freezing now then running heaters now runs risk of building up ice later; less like;y to blow onto telescope but more like;y to cause damage if it does. That's why some opening restrictions are if wind speeds are low. If winds are below normal limit but above special limit then stay closed, which is frustrating. Put in cameras so we can see the snow on top. Muk: possible to add something on dome - could add structure with sloped roof? would require not only changing roof but the doors

Instrument - ARCES - earliest possible returns to service ~ Feb 16 but it could extend beyond that - big volume to pump down, cooling will be rather delicate. It has been decade(s) since we've done this in winter time. Do have all replacement parts for fill system in place and ready to be installed. We'll have an update later this week.

DIS - future outlook - retirement Russet - we have tried every intervention we can do from the outside to recover the red camera Currently don't have in house expertise to cover repair. May be a few things to try next week. We No one using Couple of slots left for gratings in KOSMOS - someone at UW likes DIS because higher res, other because get whole spectrum in one shot - could add lower res or higher res gratings Joanne - vote for higher res for velocities - determining if star is member of globular cluster Russet: KOSMOS does have to grisms not gratings. 4 open slots but 1 needs to be left open (2 higher res and one lower?)

Joanne - any estimates of costs of grisms? NC : estimates $10-30k? Do have a complete set of 1.25“ slits (low and high pos) better matched to site seeing, can optimally sample site seeing now

There have been some updates to Q1 based largely on reshuffling ARCES time around. Short slot on Feb 18B and Feb 22A (HN - 1 hr) - can't guarantee that ARCES will be back in time, not sure if can use it to repay echelle users but anyone who lost weather free to request Feb 18B, Feb 22A is bright. Have some additional time available in March (DD01 - full night) and could request other time in March.

Q2 allocation emails went to schedulers. Requests are due by 2/23. Going on assumption that echelle will be back. DIS Red bad.

Q1 schedule is basically full. One week when have classes on site is listed as unavailable. q2 call in mid-March.

• Jan. 2024 AAS Recap - thanks to those who participated in booth - great to see the users who say “my first observing was at APO” - Jamey enjoys going. Misty - motivation - recruitment for ARC partners? science highlights? job openings/recruitment?
• 30th anniversary celebration? - possibility to extend celebration at BoG meeting? Misty and Joanne enjoyed 2014 meeting, George Wallerstein memorial something, star party + small conference

Open action items from previous meetings:

• None

DIS decommissioning?

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