apo-wiki

Attending: Nancy Chanover (NMSU), Kristian, Anne, Aleksandr, Michael H, Amanda, Misty, Adam, Kristian, Chip, Kevin, Bill , Sarah T

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), Ben W, Shane

• Wyoming - nothing to report
• Williams - nothing to report (by email)
• Washington - nothing to report
• UVa - web site - current
• Oklahoma - nothing to report
• NMSU - nothing to report
• JHU - nothing to report
• Georgia State - nothing to report
• Colorado - nothing to report
• Colgate - no report
• BYU - question/comment on users from to access - BYU

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.

1 student visit last month, closed 2 nights due to ice on enclosure. Instruments- KOSMOS and ARCTIC each had some problems. KOSMOS - when commanded the disperser wheel sometimes gets stuck - operator runs up and moves it by hand - happened once. Had another instance where camera focus wasn't set and caused confusion re: telescope focus - happened once and was corrected. Failures of UW manufactured silicon wafer slits - stress cracks likely due to differential expansion of aluminum holds. Need to identify manufacturer for new spares/replacements. ARCTIC - failure of filter wheel - caught in afternoon so didn't affect observing - recovery was more difficult than usual for night staff - engineering staff assisted. Instrument exposure was stuck and couldn't do more - init done, caused dropped quad, user used single amplifier for the rest of night. More serious issue with ion pump and loss of vacuum to instrument. Failure of high voltage cable - welded to pump, needed to replace pump and cable. Brought back - thanks to Cary who came in over time off during break to restore instrument. First biases were achieved with new SoonerCam setup. Starting to develop new ICC software and trying to learn lower level commands for triggering camera. Preliminary but noteworthy that got camera biases. Intemritten failure of ThAr lamp power supply for ARCES - cleaned and did temp cleaning. Users should still check exp to make sure have enough DIS decommissioning continues, decabled but on flor - on going, No issues with TSpec or NICFPS, APOLLO working well. Noted about Harry Abbot hire. Site infrastructure review

The Q1 schedule is posted. There is some OPEN time available on Jan 18A, Feb/Mar - keep an eye out for those.

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. 1 open week at end of quarter.

• 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: NSF pending, state of NM funds, AAS poster, SPIE papers, PDR in Q2
• Ocotillo: Progressing, camera characterization, software, have grating and few optics and fiber in hand, functional shop, lab manager leaving/hiring to replace, BS/MS position.

Schedules are linked from old web site - sort out certs, working by end of today. http://35m-schedule.apo.nmsu.edu/2026Q1.shtml

Aleksandr -

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.

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