Apache Point Observatory
New Mexico, USA

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ARC 3.5-m Instrument News

Note: Comments in bold are to catch the readers attention as the most relevant for their upcoming science observations

News Worthy Items

• ARCES is available. See below for more information.
• DIS is available. Slated for decommission. See below for more information.
• AGILE is available. See below for more information.
• ARCTIC is available. See below for more information.
• KOSMOS is available. See below for more information.
• NICFPS is available. See below for more information.
• Triplespec is available. See below for more information.

Current Status

Instrument issues which our users should be aware of before taking data. For historical information go here. For future instrumentation or planned upgrades go here.

• NOTE (2012-01-24): APO still does not recommend taking dome flats with AGILE. More information can be found here.
• 2025-05-05: TEC work is in progress. Camera currently only has 100kHz readout.
• 2025-04-28: Camera currently only has 100kHz readout.
• 2025-04-21: Camera currently only has 100kHz readout.
• 2025-04-14: Camera currently only has 100kHz readout.
• 2025-04-07: Camera currently only has 100kHz readout.
• 2025-03-31: Camera currently only has 100kHz readout.
• 2025-03-24: Camera has been repaired. Shipping back to site today.
• 2025-03-24 Until further notice: Instrument CCD thermal electric cooler (TEC) has failed. We have been unable to bring it back at this time. The camera is unavailable for use until cooling can be restored. Thermalcontrol and CCD readout is onthe same board so it is not a simple matter to troubleshoot.
• 2025-03-17: Camera has been shiped back to Vendor. Programmable gain still not fuctioning. Expected repair date March 21 2025.
• 2025-03-10: Camera has been shiped back to Vendor. Programmable gain still not fuctioning. Expected repair date March 21 2025.
• 2025-03-03: Camera has been shiped back to Vendor. Programmable gain still not fuctioning. Expected repair date March 21 2025.
• 2025-02-24: Camera has been shiped back to Vendor. Programmable gain still not fuctioning. Expected repair date March 21 2025.
• 2025-02-17: Camera has been shiped back to Vendor. Programmable gain still not fuctioning. Working with vendor to toubleshoot for repair.
• 2025-02-07: Camera is back from repair. Programmable gain still not fuctioning. Working with vendor to toubleshoot for repair.
• 2025-01-13: The camera is back out for repair. Programmable gain control was no longer available. Sent back to evaluate the problem. RAM was changed but did not correct the problem. Awaiting a further status report.
• 2025-01-06: The camera is back out for repair. Programmable gain control was no longer available. Sent back to evaluate the problem. Awaiting a status report.
• 2025-01-02: The camera is back out for repair. Programmable gain control was no longer available. Sent back to evaluate the problem. Awaiting a status report.

• NOTE (2022): Most recent interorder ratio plot can be found here.
• 2025-05-12: The instrument IOL is excellent.
• 2025-05-05: The instrument IOL is excellent.
• 2025-04-28: The instrument IOL is excellent.
• 2025-04-21: The instrument IOL is excellent.
• 2025-04-14: The instrument IOL is excellent.
• 2025-04-07: The instrument IOL is excellent.
• 2025-03-31: The instrument IOL is excellent.
• 2025-03-24: The instrument IOL is excellent.
• 2025-03-17: The instrument IOL is excellent.
• 2025-03-10: The instrument IOL is excellent.
• 2025-03-03: The instrument IOL is excellent.
• 2025-02-24: The instrument IOL is excellent.
• 2025-02-17: The instrument IOL is excellent.
• 2025-02-07: The instrument IOL is excellent.
• 2025-01-13: The instrument IOL is excellent.
• 2025-01-06: The instrument IOL is excellent.
• 2025-01-02: The instrument IOL is excellent.

• NOTE: Please consult with the Observing Specialist if you wish to take dome/cover flats with ARCTIC. With the supplemental baffle there is a flat field that is dependant on telescope position (altitude) and rotator angle that should be taken into account when taking flats.
• 2025-05-12: The instrument is performing nominally, Minus Diffuser Rotator.
• 2025-05-05: The instrument is performing nominally, Minus Diffuser Rotator.
• 2025-04-28: The instrument is performing nominally, Minus Diffuser Rotator.
• 2025-04-21: The instrument is performing nominally, Minus Diffuser Rotator.
• 2025-04-14: The instrument is performing nominally, Minus Diffuser Rotator.
• 2025-04-07: The instrument is performing nominally, Minus Diffuser Rotator.
• 2025-03-31: The instrument is performing nominally, Minus Diffuser Rotator.
• 2025-03-24: The instrument is performing nominally, Minus Diffuser Rotator. As of 2025-03-10 at 1733 local time Bias at Medium Gain setting are reading low. Shutter found stuck on night of 2025-03-17.
• 2025-03-17: The instrument is performing nominally. As of 2025-03-10 at 1733 local time Bias at Medium Gain setting are reading low. As of 2025-03-11 Diffuser has been removed for service. Reinstalled 2025-03-13 Rotator still offline for further troubleshooting.
• 2025-03-10: The instrument is performing nominally, minus Diffuser Rotator. As of 2025-03-10 at 1733 local time Bias at Medium Gain setting are reading low.
• 2025-03-03: The instrument ion pump is being serviced as of 2025-03-03. Service completed 2025-03-06. Arctic has a new Ion Pump. The instrument is performing nominally, minus Diffuser Rotator.
• 2025-02-24: The instrument ion pump is still struggling to maintain vaccum. Instrument was placed on the vacuum pump on 2025-02-22. The instrument is performing nominally.
• 2025-02-17: The instrument ion pump is still struggling to maintain vaccum. We are looking for windows to replace it. The instrument is performing nominally.
• 2025-02-07: The instrument ion pump faulted on the night of 2025-02-02 and again 2025-02-03. Cryostat was vaccum pumped both times. The instrument is performing nominally.
• 2025-01-13: The instrument is performing nominally except for the known water spots on the fore optics.
• 2025-01-06: The instrument ion pump was replaced, the cryostat evacuated and instrument cooled.
• 2025-01-03: The instrument ion pump failed in the early hours of the morning. Placed instrument of vacuum pump and started warming. Will change out the ion pump when the cryostat is above freezing.
• 2025-01-02: The instrument ion pump is still struggling to maintain vaccum. We are looking for windows to replace it. Instrument rotation range on the NA2 guider has been restricted to +/- 90 degrees.

• 2025-05-12: Marked degradation for ccd contamination on both cameras. The instrument is performing nominally otherwise.
• 2025-05-05: Marked degradation for ccd contamination on both cameras. The instrument is performing nominally otherwise.
• 2025-04-28: Marked degradation for ccd contamination on both cameras. The instrument is performing nominally otherwise.
• 2025-04-21: Marked degradation for ccd contamination on both cameras. The instrument is performing nominally otherwise.
• 2025-04-14: Marked degradation for ccd contamination on both cameras. The instrument is performing nominally otherwise.
• 2025-04-07: Marked degradation for ccd contamination on both cameras. The instrument is performing nominally otherwise.
• 2025-03-31: Marked degradation for ccd contamination on both cameras. The instrument is performing nominally otherwise.
• 2025-03-24: Marked degradation for ccd contamination on both cameras. The instrument is performing nominally otherwise.
• 2025-03-17: Marked degradation for ccd contamination on both cameras. The instrument is performing nominally otherwise.
• 2025-03-10: Marked degradation for ccd contamination on both cameras. The instrument is performing nominally otherwise.
• 2025-03-03: Marked degradation for ccd contamination on both cameras. The instrument is performing nominally otherwise.
• 2025-02-24: Marked degradation for ccd contamination on both cameras. The instrument is performing nominally otherwise.
• 2025-02-17: Marked degradation for ccd contamination on both cameras. The instrument is performing nominally otherwise.
• 2025-02-07: Marked degradation for ccd contamination on both cameras. The instrument is performing nominally otherwise.
• 2025-01-13: Marked degradation for ccd contamination on both cameras. The instrument is performing nominally otherwise.
• 2025-01-06: Marked degradation for ccd contamination on both cameras. The instrument is performing nominally otherwise.
• 2025-01-02: Marked degradation for ccd contamination on both cameras. The instrument is performing nominally otherwise.

• 2025-05-12: Instrument is available for science and performing nominally.
• 2025-05-05: Instrument is available for science and performing nominally.
• 2025-04-28: Instrument is available for science and performing nominally.
• 2025-04-21: Instrument is available for science and performing nominally.
• 2025-04-14: Instrument is available for science and performing nominally.
• 2025-04-07: Instrument is available for science and performing nominally.
• 2025-03-31: Instrument is available for science and performing nominally.
• 2025-03-24: Instrument is available for science and performing nominally.
• 2025-03-17: IEB 1 power cycled on 2025-03-11. Instrument is available for science and performing nominally.
• 2025-03-10: Instrument is available for science and performing nominally.
• 2025-03-03: Instrument is available for science and performing nominally.
• 2025-02-24: Instrument is available for science and performing nominally.
• 2025-02-17: Instrument is available for science and performing nominally.
• 2025-02-07: Instrument is available for science and performing nominally.
• 2025-01-13: Instrument is available for science and performing nominally.
• 2025-01-06: Instrument is available for science and performing nominally.
• 2025-01-02: Instrument is available for science and performing nominally.

• 2025-04-12: The instrument is performing nominally.
• 2025-05-05: The instrument is performing nominally.
• 2025-04-28: The instrument is performing nominally.
• 2025-04-21: The instrument is performing nominally.
• 2025-04-14: The instrument is performing nominally.
• 2025-04-07: The instrument is performing nominally.
• 2025-03-31: The instrument is performing nominally.
• 2025-03-24: The instrument is performing nominally.
• 2025-03-17: The instrument is performing nominally.
• 2025-03-10: The instrument is performing nominally.
• 2025-03-03: The instrument is performing nominally.
• 2025-02-24: The instrument is performing nominally.
• 2025-02-17: The instrument is performing nominally.
• 2025-02-07: The instrument is performing nominally.
• 2025-01-13: The instrument is performing nominally.
• 2025-01-06: The instrument is performing nominally.
• 2025-01-02: The instrument is performing nominally.

• 2025-05-12: The instrument is performing nominally.
• 2025-05-05: The instrument is performing nominally.
• 2025-04-28: The instrument is performing nominally.
• 2025-04-21: The instrument is performing nominally.
• 2025-04-14: The instrument is performing nominally.
• 2025-04-07: The instrument is performing nominally.
• 2025-03-31: The instrument is performing nominally.
• 2025-03-24: The instrument is performing nominally.
• 2025-03-17: The instrument is performing nominally.
• 2025-03-10: The instrument is performing nominally.
• 2025-03-03: The instrument is performing nominally.
• 2025-02-24: The instrument is performing nominally.
• 2025-02-17: The instrument is performing nominally.
• 2025-02-07: The instrument is performing nominally.
• 2025-01-13: The instrument is performing nominally.
• 2025-01-06: The instrument is performing nominally.
• 2025-01-02: The instrument is performing nominally.

• 2025-05-12: The instrument is operating nominally.
• 2025-05-05: The instrument is operating nominally.
• 2025-04-28: The instrument is operating nominally.
• 2025-04-21: The instrument is operating nominally.
• 2025-04-14: The instrument is operating nominally.
• 2025-04-07: The instrument is operating nominally.
• 2025-03-31: The instrument is operating nominally.
• 2025-03-24: The instrument is operating nominally.
• 2025-03-17: The instrument is operating nominally.
• 2025-03-10: The instrument is operating nominally.
• 2025-03-03: The instrument is operating nominally.
• 2025-02-24: The instrument is operating nominally.
• 2025-02-17: The instrument is operating nominally.
• 2025-02-07: The instrument is operating nominally.
• 2025-01-13: The instrument is operating nominally.
• 2025-01-06: The instrument is operating nominally.
• 2025-01-02: The instrument is operating nominally.

The information on this page is up to date as of March 17, 2025. This page is maintained by the 3.5-m Instrument Specialist .