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Attending: Nancy Chanover (NMSU), Kevin Schlaufman (JHU), Misty Bentz (GSU), Russet McMillan (APO), Joanne Hughes (Seattle U), Zach Berta-Thompson (CU), Anne Verbiscer (UVa), Ben Williams (UW), Moire Prescott (NMSU), Sarah Tuttle (UW)

• JHU - nothing to report
• UVa - nothing to report
• Georgia State - nothing to report
• Oklahoma - no report
• NMSU - nothing to report
• Colorado - nothing to report
• BYU - nothing to report (by email)
• Washington - nothing to report (by email)
• Seattle - nothing to report
• Wyoming - no report
• NAPG - no report

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

3.5-m Telescope and Instruments Highlights, 4/01/25 – 05/01/25

1) Overview

The frequency of higher winds and elevated dust levels improved somewhat during the month of April. APO experienced several days of particularly bad dust events ending in accumulation of several inches of snow. The precipitation melted within a day and did little to affect our high fire danger. We had a visiting class from OU and another observing team from NMSU on site this month. A NASA team was on site for APOLLO maintenance as well working with site staff.

2) Operations

3.5m Telescope: Telescope is working as expected.

0.5m Telescope: Telescope is working as expected. ACP Library support errors are still occurring even with the dcam-spare camera swap but with much lower frequency.

KOSMOS: System is cooled and stable.

ARCTIC: The diffuser rotation mechanism is still unreliable even after a full servicing. Troubleshooting is continuing. The mechanism that moves the diffuser in and out of the optical path is still functional in the meantime. The rest of the instrument is cooled and stable.

Agile: The camera is operational but only in slow readout mode. The Agile instrument rotator is still not performing nominally and we are troubleshooting it further.

ARCES: System is currently up and usable.

DIS: System is cooled but in an unknown state for science.

NICFPS: System is cooled and usable.

TripleSpec: System is cooled and usable.

APOLLO: The system is currently experiencing some technical issues with the laser at the time of this report. The servicing trip had to be extended to attempt repairs. Hopefully an update will be able to be given at the time of the meeting.

The ARCTIC diffuser rotation mechanism has been challenging to repair. The symptom is that when commanded to rotate, the diffuser shifts in position and then stops. This is worse than having no rotation, so the rotation functionality is currently disabled. It will require a complete rebuild in order to get it working so this is on the longer-term to-do list.

The Agile instrument rotator is exhibiting problems. Unfortunately they are occurring too frequently for science, but too intermittently for detailed testing, which makes it hard to diagnose. This is still being worked on.

The time in Q2 is fully allocated; no OPEN or DD slots remain.

The Q2 ARCSAT schedule has one week of OPEN time remaining (June 12-19).

The 3.5m summer shutdown is scheduled for 7-17 July, inclusive. Institutional allocations for Q3 were sent out last week and all requests are due on May 23. DIS will no longer be made available for proposers.

A replacement high speed imager, SoonerCam, is under development. We expect to be able to share an information/specification sheet or white paper about the instrument fairly soon. In the meantime, a survey of all past/present/future users of such an instrument (i.e. current and former Agile users, or those who want to use a modern high speed imager) was distributed. We really need to hear from users concerning anticipated needs for frame rate, binning, etc. as this information will drive some design decisions. We plan to add a focal reducer but the pixels are currently very small. Here is the email sent to 35m-general requesting survey responses:

Dear APO 3.5m users, We are purchasing a new qCMOS high-speed camera, SoonerCam, to replace the old camera on Agile. This camera provides a read-noise of 0.3 e- in the ultra-quiet scan mode. It's a 4096×2304 pixel camera with 4.5 micron pixels. It can provide up to 25 frames/s in this mode. Using Agile's current setup, the camera provides 0.05 arcsec per pixel (or a field of view of 115“ x 205”).

Before finalizing the design and installation at the telescope, we would love to hear your thoughts or feedback on what would make this new camera suitable for your science needs.

If you are interested in using this new capability, can you please provide feedback on: https://docs.google.com/forms/d/e/1FAIpQLSeJG6zQg7YtGxGhAtaKULHyzZVZe29uHCiegcHdM0edglN1gw/viewform?usp=sharing

Thank you, On behalf of the SoonerCam team (including the Astro group at OU, Sarah Tuttle, Bill Ketzeback and the APO engineering/software team, and Nancy Chanover), -Muk

Work on the new optical echelle spectrograph continues with the goal of completing the Preliminary Design Review this calendar year. Another grant proposal is in the works.

We have no updates concerning Ocotillo.

This group is still meeting and exploring various options for the future of ARCSAT.

Open action items from previous meetings:

• Nancy: get Mt. Cuba Foundation proposal for new KOSMOS grisms submitted. STATUS: OPEN. The proposal is done; Nancy needs to confirm with NMSU's Office of Grants and Contracts whether they need to be involved in the submission since it's a small proposal. She plans to submit it before the next Users Committee meeting.
• UC reps: remind your users to review the Q2 schedule and request OPEN/DD time if they can make a good case for it. STATUS: CLOSED.

New action items from this meeting:

• UC reps: ask your users to complete the survey regarding needs/desires for a high speed imaging capability. The link to this survey was sent out to 35m-general on May 6, 2025 by Mukremin Kilic, and is also included above. STATUS: OPEN.

Nancy requested input from the UC reps concerning user needs/desires for data archiving. There was no clear consensus about what (if anything) APO should provide or facilitate in this area, but several UC members stated that it would be more useful to have reduced data available in an archive more so than raw data files.

The next meeting will be on June 3, 2025 at 10:30 MDT.