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. See below for more information.
• AGILE is available. See below for more information.
• ARCTIC 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.

• 2021-04-12: Instrument is operating nominally.
• 2021-04-05: Instrument is operating nominally.
• 2021-03-29: Instrument is operating nominally.
• 2021-02-22: Instrument is operating nominally.
• 2021-02-15: Instrument is operating nominally.
• 2021-02-08: Instrument is operating nominally.
• 2021-02-01: Instrument is operating nominally.
• 2021-01-25: Instrument is operating nominally.
• 2021-01-18: Instrument is operating nominally.
• 2021-01-11: Instrument is operating nominally.
• 2021-01-05: Instrument is operating nominally.
• 2012-01-24: APO still does not recommend taking dome flats with AGILE. More information can be found here.

• 2021-04-12: Instrument has been operating nominally.
• 2021-04-05: Instrument has been operating nominally.
• 2021-03-29: Instrument has been operating nominally.
• 2021-03-07: Installed a new Thorium Argon (ThAr) bulb to replace a weakening bulb in the bluest orders.
• 2021-02-25: The instrument was using an unusal amount of LN2 and there were temperature spikes during fills. We tracked it down to a popped pressure relief valve. Reseated, the instrument is performing nominally now.
• 2021-02-22: The instrument is operating nominally.
• 2021-02-15: The instrument is operating nominally.
• 2021-02-08: The instrument is operating nominally.
• 2021-02-01: The instrument is operating nominally.
• 2021-01-25: The instrument is operating nominally. IOL continues to slowly improve with colder ambient temperatures.
• 2021-01-18: The instrument is operating nominally. IOL continues to slowly improve with colder ambient temperatures.
• 2021-01-11: The instrument is operating nominally. IOL continues to slowly improve with colder ambient temperatures.
• 2021: Most recent interorder ratio plot can be found here.
• 2021-01-05: The instrument is operating nominally. IOL continues to slowly improve with colder ambient temperatures.

• 2021-04-12: The instrument is operating nominally.
• 2021-04-05: The instrument is operating nominally. The diffuser in/out motion has been repaired and no longer requires rotating the instrument for gravity assist.
• 2021-03-29: The instrument is operating nominally. The diffuser in/out motion has required turning the instrument upside down/ or zero rotation respectably for gravity assist. Investigating the problem.
• 2021-02-22: The instrument is operating nominally. Users are reminded at ambient temperatures below -10C the shutter becomes unreliable and sticks open/shut. Please inspect your data carefully and report any issue found. There is a manual reset that the observing specialist can activate.
• 2021-02-15: The instrument is operating nominally. Users are reminded at ambient temperatures below -10C the shutter becomes unreliable and sticks open/shut. Please inspect your data carefully and report any issue found. There is a manual reset that the observing specialist can activate.
• 2021-02-08: The instrument is operating nominally. Users are reminded at ambient temperatures below -10C the shutter becomes unreliable and sticks open/shut. Please inspect your data carefully and report any issue found. There is a manual reset that the observing specialist can activate.
• 2021-02-01: The instrument is operating nominally. Users are reminded at ambient temperatures below -10C the shutter becomes unreliable and sticks open/shut. Please inspect your data carefully and report any issue found. There is a manual reset that the observing specialist can activate.
• 2021-01-25: The instrument is operating nominally. Users are reminded at ambient temperatures below -10C the shutter becomes unreliable and sticks open/shut. Please inspect your data carefully and report any issue found. There is a manual reset that the observing specialist can activate.
• 2021-01-18: The instrument is operating nominally. Users are reminded at ambient temperatures below -10C the shutter becomes unreliable and sticks open/shut. Please inspect your data carefully and report any issue found. There is a manual reset that the observing specialist can activate.
• 2021-01-11: The instrument is operating nominally. Users are reminded at ambient temperatures below -10C the shutter becomes unreliable and sticks open/shut. Please inspect your data carefully and report any issue found. There is a manual reset that the observing specialist can activate.
• 2021: APO does not recommend taking dome flats with ARCTIC. We are working on designing a supplemental baffle to correct the problem with cover flats. Currently cover flats produce a gradient across the flat field that is dependant on telescope position (altitude) and rotator angle.
• 2021-01-05: The instrument is operating nominally. Users are reminded at ambient temperatures below -10C the shutter becomes unreliable and sticks open/shut. Please inspect your data carefully and report any issue found. There is a manual reset that the observing specialist can activate.

• 2021-04-12: Both red and blue cameras are showing good to excellent performance with regard to contamination. Russet does report she can now measure the contamination on both cameras. The red camera is running unseasonably warm as well.
• 2021-04-05: Both red and blue cameras are showing good to excellent performance with regard to contamination. Russet does report she can now measure the contamination on the red camera. The red camera is running unseasonably warm as well.
• 2021-03-29: Both red and blue cameras are showing good to excellent performance with regard to contamination. However Russet does report that she is seeing the beginning signs of return of contamination. The red camera is running unseasonably warm as well.
• 2021-02-22: Both red and blue cameras are showing good to excellent performance with regard to contamination.
• 2021-02-15: Both red and blue cameras are showing good to excellent performance with regard to contamination.
• 2021-02-08: Both red and blue cameras are showing good to excellent performance with regard to contamination.
• 2021-02-01: Both red and blue cameras are showing good to excellent performance with regard to contamination.
• 2021-01-25: Russet reports both red and blue cameras are showing good to excellent performance with regard to contamination.
• 2021-01-18: Russet reports both red and blue cameras are showing good to excellent performance with regard to contamination.
• 2021-01-11: Russet reports both red and blue cameras are showing good to excellent performance with regard to contamination.
• 2021-01-05: Russet reports both red and blue cameras are showing good to excellent performance with regard to contamination.

• 2021-04-12: The instrument is performing nominally with the occasional need to reset the controller due to corrupted images. These have been seen most often when the instrument is upside down. You may asked to rotate your field 180 degrees to minimize these events. Additionally we have seen an increase in the times the active port on the terminal server that services the robotics has locked up. Cause is unknown but if recognized immediately the fix is just a few minutes.
• 2021-04-05: The instrument is performing nominally with the occasional need to reset the controller due to corrupted images. These have been seen most often when the instrument is upside down. You may asked to rotate your field 180 degrees to minimize these events.
• 2021-03-29: The instrument is performing nominally with the occasional need to reset the controller due to corrupted images. These have been seen most often when the instrument is upside down. You may asked to rotate your field 180 degrees to minimize these events.
• 2021-02-22: The instrument is performing nominally with the occasional need to reset the controller due to corrupted images. These have been seen most often when the instrument is upside down. You may asked to rotate your field 180 degrees to minimize these events.
• 2021-02-15: The instrument is performing nominally with the occasional need to reset the controller due to corrupted images. These have been seen most often when the instrument is upside down. You may asked to rotate your field 180 degrees to minimize these events.
• 2021-02-08: The instrument is performing nominally with the occasional need to reset the controller due to corrupted images. These have been seen most often when the instrument is upside down. You may asked to rotate your field 180 degrees to minimize these events.
• 2021-02-01: The instrument is performing nominally with the occasional need to reset the controller due to corrupted images. These have been seen most often when the instrument is upside down. You may asked to rotate your field 180 degrees to minimize these events.
• 2021-01-25: The instrument is performing nominally with the occasional need to reset the controller due to corrupted images. These have been seen most often when the instrument is upside down. You may asked to rotate your field 180 degrees to minimize these events.
• 2021-01-18: The instrument is performing nominally with the occasional need to reset the controller due to corrupted images. These have been seen most often when the instrument is upside down. You may asked to rotate your field 180 degrees to minimize these events.
• 2021-01-11: The instrument is performing nominally with the occasional need to reset the controller due to corrupted images. These have been seen most often when the instrument is upside down. You may asked to rotate your field 180 degrees to minimize these events.
• 2021-01-05: The instrument is performing nominally with the occasional need to reset the controller due to corrupted images. These have been seen most often when the instrument is upside down. You may asked to rotate your field 180 degrees to minimize these events.
• 2020-08-17: The instrument is operating nominally however the users should be on the lookout for corrupted images. This is still occuring intermittently and not well understood. Report any corrupted images to the observing specialist so they can reset the array electronics.

• 2021-04-12: The instrument is operating nominally.
• 2021-04-05: The instrument is operating nominally.
• 2021-03-29: The instrument is operating nominally.
• 2021-02-22: The instrument is operating nominally.
• 2021-02-15: The instrument is operating nominally.
• 2021-02-01: No change in the instrument status. There still appears to be a low level pattern noise in some images. From David Decolibus: "the low-level pattern noise can be effectively avoided just by keeping the instrument upright (between -90 and +90 mount). In the twelve nights of observing I've had (beginning in September), I have not seen the pattern noise in *any* data in which I have kept the instrument upright. A few exposures below the horizontal (like for a standard star) is fine, but keeping the instrument inverted for an extended period seems to introduce the pattern noise. Last night, I wasn't paying attention and the slit angle I chose was about 30 degrees below the horizontal (-120 mount) for about 30 minutes. I started to see the pattern noise on the last few frames of this data. As soon as I rotated the slit 180 degrees, the noise went away, which only confirms my suspicions that it is strongly correlated with instrument rotator position."
• 2021-02-01: No change in the instrument status. There still appears to be a low level pattern noise in some images. From David Decolibus: "the low-level pattern noise can be effectively avoided just by keeping the instrument upright (between -90 and +90 mount). In the twelve nights of observing I've had (beginning in September), I have not seen the pattern noise in *any* data in which I have kept the instrument upright. A few exposures below the horizontal (like for a standard star) is fine, but keeping the instrument inverted for an extended period seems to introduce the pattern noise. Last night, I wasn't paying attention and the slit angle I chose was about 30 degrees below the horizontal (-120 mount) for about 30 minutes. I started to see the pattern noise on the last few frames of this data. As soon as I rotated the slit 180 degrees, the noise went away, which only confirms my suspicions that it is strongly correlated with instrument rotator position."
• 2021-02-01: No change in the instrument status. There still appears to be a low level pattern noise in some images. From David Decolibus: "the low-level pattern noise can be effectively avoided just by keeping the instrument upright (between -90 and +90 mount). In the twelve nights of observing I've had (beginning in September), I have not seen the pattern noise in *any* data in which I have kept the instrument upright. A few exposures below the horizontal (like for a standard star) is fine, but keeping the instrument inverted for an extended period seems to introduce the pattern noise. Last night, I wasn't paying attention and the slit angle I chose was about 30 degrees below the horizontal (-120 mount) for about 30 minutes. I started to see the pattern noise on the last few frames of this data. As soon as I rotated the slit 180 degrees, the noise went away, which only confirms my suspicions that it is strongly correlated with instrument rotator position."
• 2021-01-25: No change in the instrument status. There still appears to be a low level pattern noise in some images. From David Decolibus: "the low-level pattern noise can be effectively avoided just by keeping the instrument upright (between -90 and +90 mount). In the twelve nights of observing I've had (beginning in September), I have not seen the pattern noise in *any* data in which I have kept the instrument upright. A few exposures below the horizontal (like for a standard star) is fine, but keeping the instrument inverted for an extended period seems to introduce the pattern noise. Last night, I wasn't paying attention and the slit angle I chose was about 30 degrees below the horizontal (-120 mount) for about 30 minutes. I started to see the pattern noise on the last few frames of this data. As soon as I rotated the slit 180 degrees, the noise went away, which only confirms my suspicions that it is strongly correlated with instrument rotator position."
• 2021-01-18: No change in the instrument status. There still appears to be a low level pattern noise in some images. From David Decolibus: "the low-level pattern noise can be effectively avoided just by keeping the instrument upright (between -90 and +90 mount). In the twelve nights of observing I've had (beginning in September), I have not seen the pattern noise in *any* data in which I have kept the instrument upright. A few exposures below the horizontal (like for a standard star) is fine, but keeping the instrument inverted for an extended period seems to introduce the pattern noise. Last night, I wasn't paying attention and the slit angle I chose was about 30 degrees below the horizontal (-120 mount) for about 30 minutes. I started to see the pattern noise on the last few frames of this data. As soon as I rotated the slit 180 degrees, the noise went away, which only confirms my suspicions that it is strongly correlated with instrument rotator position."
• 2021-01-11: No change in the instrument status. There still appears to be a low level pattern noise in some images. From David Decolibus: "the low-level pattern noise can be effectively avoided just by keeping the instrument upright (between -90 and +90 mount). In the twelve nights of observing I've had (beginning in September), I have not seen the pattern noise in *any* data in which I have kept the instrument upright. A few exposures below the horizontal (like for a standard star) is fine, but keeping the instrument inverted for an extended period seems to introduce the pattern noise. Last night, I wasn't paying attention and the slit angle I chose was about 30 degrees below the horizontal (-120 mount) for about 30 minutes. I started to see the pattern noise on the last few frames of this data. As soon as I rotated the slit 180 degrees, the noise went away, which only confirms my suspicions that it is strongly correlated with instrument rotator position."
• 2021-01-05: No change in the instrument status. There still appears to be a low level pattern noise in some images. From David Decolibus: "the low-level pattern noise can be effectively avoided just by keeping the instrument upright (between -90 and +90 mount). In the twelve nights of observing I've had (beginning in September), I have not seen the pattern noise in *any* data in which I have kept the instrument upright. A few exposures below the horizontal (like for a standard star) is fine, but keeping the instrument inverted for an extended period seems to introduce the pattern noise. Last night, I wasn't paying attention and the slit angle I chose was about 30 degrees below the horizontal (-120 mount) for about 30 minutes. I started to see the pattern noise on the last few frames of this data. As soon as I rotated the slit 180 degrees, the noise went away, which only confirms my suspicions that it is strongly correlated with instrument rotator position."

• 2021-04-12: The instrument is operating nominally. It is still requiring nearly daily or multiple resets of the USB with a nub restart.
• 2021-04-05: The instrument is operating nominally. It is still requiring nearly daily or multiple resets of the USB with a nub restart.
• 2021-03-29: The instrument is operating nominally.
• 2021-02-22: The instrument is operating nominally.
• 2021-02-15: The instrument is operating nominally.
• 2021-02-08: The instrument is operating nominally.
• 2021-02-01: The instrument had some issues at the end of December, we believe we have tracked the problem down to a loose power cord on the instrument control computer.
• 2021-01-25: The instrument had some issues at the end of December, we believe we have tracked the problem down to a loose power cord on the instrument control computer.
• 2021-01-18: The instrument had some issues at the end of December, we believe we have tracked the problem down to a loose power cord on the instrument control computer.
• 2021-01-11: The instrument had some issues at the end of December, we believe we have tracked the problem down to a loose power cord on the instrument control computer.
• 2021-01-05: The instrument had some issues at the end of December, we believe we have tracked the problem down to a loose power cord on the instrument control computer.

The information on this page is up to date as of April 12, 2021. This page is maintained by the 3.5-m Telescope Engineer .