apo-wiki

Attending: Nancy Chanover (NMSU),

Sarah Tuttle (UW), Joanne Hughes (Seattle U), Bill Ketzeback (APO), Michael Hayden (OU), Eric Bellm (UW), Moire Prescott (NMSU), Aleksandr Mosenkov (BYU), Ben Williams (UW), Misty Bentz (GSU), Kevin Schlaufman (JHU), Anne Verbiscer (UVa)

• Wyoming - no report
• Williams - nothing to report (by email)
• Washington - nothing to report other than users are eager to hear about KOSMOS updates
• UVa - nothing to report
• Oklahoma - nothing to report other than users are eager about KOSMOS updates
• NMSU - nothing to report other than users are eager to hear about KOSMOS updates
• JHU - nothing to report
• Georgia State - nothing to report
• Colorado - no report
• Colgate - no report
• BYU - nothing to report

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

3.5-m Telescope and Instruments Highlights, 12/02/25 – 01/13/26

1) Overview

The past month was a mix of excellent skies and very unsettled weather. About a third of the time was lost due to clouds, wind, and a few days when we could not open the enclosure due to an ice and snow storm.

We had one student training visit during this time period.

2) Operations

3.5m Telescope: The telescope is working quite well. We experienced one instance of collimation failure when one of the actuators for the secondary mirror did not reach or fail to move to the commanded position. The problem was corrected by homing the mirror. A moderate correction to collimation was applied during engineering last week.

0.5m Telescope: Telescope is working as expected. Dcam-spare was having issues with the CCD chamber frosting up. Even after multiple attempts, it could not be cleaned or made reliable. We pulled Dcam off of DIS and put it into service. Dcam and UVAcam are both available options for users.

KOSMOS: System is cold and stable. The instrument dispenser wheel had one instance of not moving when commanded. It was corrected by manually repositioning it. There was one night when the camera focus was not properly set, and some confusion resulted when the telescope focus seemed to be running low. It was corrected the next night. Some of the silicon wafers manufactured with slits have been damaged in their holders. They appear to have developed stress cracks from the differential thermal expansion of the aluminum holders. We are currently seeking companies that may be able to manufacture spares.

ARCTIC: The diffuser rotation mechanism is still unreliable even after a full servicing. The mechanism that moves the diffuser in and out of the optical path is still functional in the meantime. There was another instance this month of the filter wheel controller losing connection and requiring a reset. On another night, the instrument refused to take an exposure because another one was in progress that would not clear. An init resulted in a dropped upper left quad. The observer got back on the sky, using single amplifier mode. During the holiday break, a failure of the ion pump resulted in a loss of vacuum. The repair required a swap of the ion pump, putting the instrument back on a vacuum pump, a different ion pump controller, and a cable. Special thanks to Cary Smith, who came in over his time off to restore the instrument.

SoonerCam: The agile instrument rotator is still not performing nominally, and we will be troubleshooting it further to prepare for SoonerCam. SoonerCam parts are on hand, assembled, and software development has begun. The first biases using low-level commands were taken this past week.

ARCES: There was an intermittent failure of the thorium argon lamp power supply, resulting in lamp dropouts or weak lines. Cleaning the rheostat that controls the adjustment of amperage was a temporary fix until we can possibly repair it with a new part.

DIS: System is powered down and warm. Decommissioning plans have begun. The instrument has been decabled, and we will be lowering it off the observing floor soon.

NICFPS: System is cooled and usable.

TripleSpec: System is cooled and usable.

APOLLO: The instrument is usable for laser ranging. The team has experienced a streak of poor weather and software connection issues over the past month.

xxx

The Q1 schedule is posted. There is some OPEN time available on xxx Dec 23A (short slot) and on New Year's Eve (note added in proof: the 12/31 time is now spoken for). Users interested in the Dec 23A time should send a request to Ben, Nancy, Russet, Amanda, and their institutional schedulers.

The ARCSAT Q1 schedule is posted. xxx There are two unscheduled weeks at the end of December.

• SoonerCam: Nearly all of the parts we are expecting have come in. We will begin working on this in January.
• KOSMOS grisms (no change from last month): we are still awaiting a decision on the proposal we submitted for funds to support the purchase of three new grisms for KOSMOS.
• ASPEN: Work on the design of the new optical echelle spectrograph continues with the goal of completing the Preliminary Design Review in spring 2026. We hosted a productive ASPEN team meeting at APO and NMSU in October. We submitted another NSF proposal in mid-November.
• Ocotillo: The TEG team is working on optics mounting. We have the disperser for the red channel in hand and mounts are being fabricated in the shop. We are working to characterize and provide software for the camera. Fiber assembly will begin in early 2026.

We are tentatively planning to launch the new website on January 13, 2026. We are currently working on updating the procedure for staff access for the portion of the website that will be behind a login. The old website will still be accessible, at least for some TBD time period, but the goal is for all users to migrate to the new site and let us know if there is critical information that they can no longer find.

Nancy presented a subset of slides from her presentations to the ARC Board of Governors meeting in early November to provide the UC reps with a summary of the 2025 operations, science achievements, and plans for next year.

Open action items from previous meetings:

• Joanne Hughes: put the KOSMOS MOS data reduction software on the wiki. Joanne is waiting for an update from her colleagues at the College of Idaho. Status: OPEN.
• UC reps: remind your users to review the Q4 schedule and request OPEN/DD01 time if they can make a good case for it. Status: CLOSED.
• UC reps: please discuss the idea of archiving our 3.5m data with your users and report back with any reactions, either positive (e.g., advantages that they see to having a data archive) or negative (e.g., potential issues or concerns).

New action items from this meeting:

• UC reps: remind your users to review the Q1 schedule and request OPEN/DD01 time if they can make a good case for it. Status: CLOSED.

xxx

The next Users Committee meeting will be on Tuesday February 03 at 10:30 MST.