ARC 3.5-m Instrument News Page

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Apache Point Observatory
New Mexico, USA

ARCES

ARCES Users Guide Appendix B. Instrument History

2022: Most recent interorder ratio plot can be found here.

2023-03-18: The instrument has been cooled again and IOL is excellent. It is available for use.

2023-03-14: The instrument has been cooled again and IOL is excellent. It is availabel for use.

2023-03-11: The instrument has been partially warmed to address poor IOL. IOL ratios have plummeted. (see IOL plots).

2023-03-04: The instrument has been partially warmed to address poor IOL. IOL ratios have plummeted. (see IOL plots).

2023-02-26: The instrument is operating nominally except LN2 consumption has increaded greatly, parts on order. IOL ratios have plummeted. We are considering further intervention. (see IOL plots).

2023-02-19: The instrument is operating nominally except LN2 consumption has increaded greatly, parts on order. IOL ratios have plummeted. We are considering further intervention. (see IOL plots).

2023-02-14: The instrument is back from vacuum servicing.

2023-02-05: The instrument is warm and on the vacuum pump.

2023-01-29: The instrument is operating nominally except LN2 consumption has increaded greatly, parts on order. IOL ratios are leveling off and are in an acceptable range (see IOL plots).

2023-01-29: The instrument is operating nominally except LN2 consumption has increaded greatly, parts on order. IOL ratios are leveling off and are in an acceptable range (see IOL plots).

2023-01-22: The instrument is operating nominally except LN2 consumption has increased greatly. IOL ratios are leveling off and are in an acceptable range (see IOL plots).

2023-01-15: The instrument is operating nominally. IOL ratios are leveling off and are in an acceptable range (see IOL plots).

2023-01-08: The instrument is operating nominally. IOL ratios are leveling off and are in an acceptable range (see IOL plots).

2023-01-02: The instrument is operating nominally. IOL ratios are leveling off and are in an acceptable range (see IOL plots).

2023-12-18: The instrument is operating nominally. IOL ratios are leveling off and are in an acceptable range (see IOL plots).

2023-12-11: The instrument is operating nominally. IOL ratios are still improving and are in an acceptable range (see IOL plots).

2023-12-04: The instrument is operating nominally. IOL ratios are still improving and are in an acceptable range (see IOL plots).

2023-11-27: The instrument is operating nominally. IOL ratios are still improving and are in an acceptable range (see IOL plots).

2023-11-20: The instrument is operating nominally. IOL ratios are still improving and are in an acceptable range (see IOL plots).

2023-11-13: The instrument is operating nominally. IOL ratios are still improving and are in an acceptable range (see IOL plots).

2023-11-06: The instrument is operating nominally. IOL ratios are still improving and are in an acceptable range (see IOL plots).

2023-10-30: The instrument is operating nominally. IOL ratios are still improving and are in an acceptable range (see IOL plots).

2023-10-23: The Quartz bulb failed this morning and was replaced. There should be minimal affect on calibrations. Otherwise, the instrument is operating nominally. IOL ratios are still improving and are in an acceptable range (see IOL plots).

2023-10-16 The instrument is operating nominally. IOL ratios are improving and are in an acceptable range (see IOL plots).

2023-10-09 The instrument is operating nominally. IOL ratios are improving and are in an acceptable range (see IOL plots).

2023-10-02 The instrument is operating nominally. IOL ratios are improving and are in an acceptable range (see IOL plots).

2023-09-25 The instrument is operating nominally. IOL ratios are improving and are in an acceptable range (see IOL plots).

2023-09-18 The instrument is operating nominally. IOL ratios are dropping more quickly but are still in an acceptable range (see IOL plots).

2023-09-11 The instrument is operating nominally. IOL ratios are dropping more quickly but are still in an acceptable range (see IOL plots).

2023-09-04 The instrument is operating nominally. IOL ratios are dropping more quickly but are still in an acceptable range (see IOL plots).

2023-08-28 The instrument is operating nominally. IOL ratios are dropping more quickly but are still in an acceptable range (see IOL plots).

2023-07-14 The instrument is operating nominally. IOL ratios are dropping more quickly but are still in an acceptable range (see IOL plots).

2023-07-10 The instrument is operating nominally. IOL ratios are dropping more quickly (see IOL plots).

2023-07-03 The instrument is operating nominally. IOL ratios are slowly dropping (see IOL plots).

2023-06-26 The instrument is operating nominally. IOL ratios are slowly dropping (see IOL plots).

2023-06-19 The instrument is operating nominally. IOL ratios are slowly dropping (see IOL plots).

2023-06-12 The instrument is operating nominally. IOL ratios appear to be dropping (see IOL plots).

2023-06-05 The instrument is operating nominally. IOL ratios appear to be dropping (see IOL plots).

2023-05-30 The instrument is operating nominally. IOL ratios appear to be dropping (see IOL plots).

2023-05-22 The instrument is operating nominally. IOL ratios appear to have turned around and are dropping (see IOL plots).

2023-05-15 The instrument is operating nominally. IOL ratios appear to have turned around and are dropping (see IOL plots).

2023-05-08 The instrument is operating nominally. IOL ratios appear to have turned around and are dropping (see IOL plots).

2023-04-24 The instrument is operating nominally. IOL ratios appear to have turned around (see IOL plots).

2023-04-17 The instrument is operating nominally. IOL ratios appear to have leveled off (see IOL plots).

2023-04-10 The instrument is operating nominally. IOL ratios appear to have leveled off (see IOL plots).

2023-04-03 The instrument is operating nominally. IOL ratios appear to have leveled off (see IOL plots).

2023-03-27 The instrument is operating nominally. IOL ratios appear to have leveled off (see IOL plots).

2023-03-20 The instrument is operating nominally. IOL ratios appear to have leveled off (see IOL plots).

2023-03-13 The instrument is operating nominally. IOL ratios appear to have leveled off (see IOL plots).

2023-03-06 The instrument is operating nominally. IOL ratios appear to have leveled off (see IOL plots).

2023-02-27 The instrument is operating nominally. IOL ratios appear to have leveled off (see IOL plots).

2023-02-20 The instrument is operating nominally. IOL ratios appear to be leveling off. The change has been rather slow (which is preferred).

2023-02-13 The instrument is operating nominally. IOL ratios appear to be leveling off. The change has been rather slow (which is preferred).

2023-02-06 The instrument is operating nominally. IOL ratios appear to be leveling off. The change has been rather slow (which is preferred).

2023-01-30 The instrument is operating nominally. IOL ratios appear to be leveling off. The change has been rather slow (which is preferred).

2023-01-23 The instrument is operating nominally. IOL ratios appear to be leveling off. The change has been rather slow (which is preferred).

2023-01-17 The instrument is operating nominally. IOL ratios appear to be leveling off. The change has been rather slow (which is preferred).

2022-12-12 The instrument is operating nominally. IOL ratios appear to be leveling off. The change has been rather slow (which is preferred).

2022-12-05 The instrument is operating nominally. IOL ratios appear to be leveling off. The change has been rather slow (which is preferred).

2022-11-28 The instrument is operating nominally. IOL ratios appear to be leveling off. The change has been rather slow (which is preferred).

2022-11-21 The instrument is operating nominally. IOL ratios appear to be leveling off. The change has been rather slow (which is preferred).

2022-11-14 The instrument is operating nominally. IOL ratios appear to be leveling off. The change has been rather slow (which is preferred).

2022-11-07 The instrument is operating nominally. IOL ratios appear to be leveling off. The change has been rather slow (which is preferred).

2022-10-31 The instrument is operating nominally. IOL ratios appear to be leveling off (but may still be climbing very slowly). The change has been rather slow (which is preferred).

2022-10-24 The instrument is operating nominally. IOL ratios appear to be leveling off (but may still be climbing slowly). The change has been rather slow (which is preferred).

2022-10-17 The instrument is operating nominally. IOL ratios appear to be leveling off. The change has been rather slow (which is preferred).

2022-10-10 The instrument is operating nominally. IOL ratios appear to be leveling off. The change has been rather slow (which is preferred).

2022-10-03 The instrument is operating nominally. IOL ratios appear to be leveling off. The change has been rather slow (which is preferred).

2022-09-26 The instrument is operating nominally. IOL ratios appear to be leveling off. The change has been rather slow (which is preferred).

2022-09-19 The instrument is operating nominally. IOL ratios are back on the rise in the bluest orders but are still quite acceptable. The change has been rather slow (which is preferred). The quick dip and return the first half of June coincided with a hot spell and the then a start of monsoon season which brought cooler weather and a short increase in the IOL ratio. IOL ratios are still quite good and back to March peaks. The best ratios we have experienced since 2019.

2022-09-12 The instrument is operating nominally. IOL ratios are back on the rise in the bluest orders but are still quite acceptable. The change has been rather slow (which is preferred). The quick dip and return the first half of June coincided with a hot spell and the then a start of monsoon season which brought cooler weather and a short increase in the IOL ratio. IOL ratios are still quite good and back to March peaks. The best ratios we have experienced since 2019.

2022-09-06 The instrument is operating nominally. IOL ratios are back on the rise in the bluest orders but are still quite acceptable. The change has been rather slow (which is preferred). The quick dip and return the first half of June coincided with a hot spell and the then a start of monsoon season which brought cooler weather and a short increase in the IOL ratio. IOL ratios are still quite good and back to March peaks. The best ratios we have experienced since 2019.

2022-08-29 The instrument is operating nominally. IOL ratios are back on the rise in the bluest orders but are still quite acceptable. The change has been rather slow (which is preferred). The quick dip and return the first half of June coincided with a hot spell and the then a start of monsoon season which brought cooler weather and a short increase in the IOL ratio. IOL ratios are still quite good and back to March peaks. The best ratios we have experienced since 2019.

2022-08-22 The instrument is operating nominally. IOL ratios are back on the rise in the bluest orders but are still quite acceptable. The change has been rather slow (which is preferred). The quick dip and return the first half of June coincided with a hot spell and the then a start of monsoon season which brought cooler weather and a short increase in the IOL ratio. IOL ratios are still quite good.

2022-08-15 The instrument is operating nominally. IOL ratios are declining in the bluest orders but are still quite acceptable. The change has been rather slow (which is preferred). The quick dip and return the first half of June coincided with a hot spell and the then a start of monsoon season which brought cooler weather and a short increase in the IOL ratio. IOL ratios are still quite good.

2022-08-01 The instrument is operating nominally. IOL ratios are declining in the bluest orders but are still quite acceptable. The change has been rather slow (which is preferred). The quick dip and return the first half of June coincided with a hot spell and the then a start of monsoon season which brought cooler weather and a short increase in the IOL ratio. IOL ratios are still quite good.

2022-07-25 The instrument is operating nominally. IOL ratios are declining in the bluest orders but are still quite acceptable. The change has been rather slow (which is preferred). The quick dip and return the first half of June coincided with a hot spell and the then a start of monsoon season which brought cooler weather and a short increase in the IOL ratio. IOL ratios are still quite good.

2022-07-18 The instrument is operating nominally. IOL ratios are declining in the bluest orders but are still quite acceptable. The change has been rather slow (which is preferred). The quick dip and return the first half of June coincided with a hot spell and the then a start of monsoon season which brought cooler weather and a short increase in the IOL ratio. IOL ratios are still quite good.

2022-07-11 The instrument is operating nominally. IOL ratios are declining in the bluest orders but are still quite acceptable. The change has been rather slow (which is preferred). The quick dip and return the first half of June coincided with a hot spell and the then a start of monsoon season which brought cooler weather and a short increase in the IOL ratio. IOL ratios are still quite good.

2022-07-05 The instrument is operating nominally. IOL ratios are declining in the bluest orders but are still quite acceptable. The change has been rather slow (which is preferred). The quick dip and return the first half of June coincided with a hot spell and the then a start of monsoon season which brought cooler weather and a short increase in the IOL ratio. IOL ratios are still quite good.

2022-06-27 The instrument is operating nominally. IOL ratios are declining in the bluest orders but are still quite acceptable. The change has been rather slow (which is preferred). The quick dip and return the first half of June coincided with a hot spell and the then a start of monsoon season which brought cooler weather and a short increase in the IOL ratio. IOL ratios are still quite good.

2022-06-20 The instrument is operating nominally. IOL ratios are declining in the bluest orders but are still quite acceptable. The change has been rather slow (which is preferred). IOL ratios are still quite good.

2022-06-13 The instrument is operating nominally. IOL ratios are declining in the bluest orders but are still quite acceptable. The change has been rather slow (which is preferred). IOL ratios are still quite good.

2022-06-06 The instrument is operating nominally. IOL ratios are declining in the bluest orders but are still quite acceptable. The change has been rather slow (which is preferred). IOL ratios are still quite good.

2022-06-01 The instrument is operating nominally. IOL ratios appear to be turning around in the bluest orders. The change has been rather slow (which is preferred). IOL ratios are still quite good.

2022-05-23 The instrument is operating nominally. IOL ratios appear to be turning around in the bluest orders. Thechange has been rather slow (which is preferred). IOL ratios are still quite good.

2022-05-16 The instrument is operating nominally. IOL ratios appear to be turning around in the bluest orders. Thechange has been rather slow (which is preferred). IOL ratios are still quite good.

2022-05-09 The instrument is operating nominally. IOL ratios appear to be turning around in the bluest orders. Thechange has been rather slow (which is preferred). IOL ratios are still quite good.

2022-05-02 The instrument is operating nominally. IOL ratios appear to be turning around in the bluest orders.

2022-04-25 The instrument is operating nominally. IOL ratios appear to be turning around in the bluest orders.

2022-04-18 The instrument is operating nominally. IOL ratios appear to be leveling off in the bluest orders.

2022-04-14 The instrument is operating nominally. IOL ratios appear to be leveling off in the bluest orders.

2022-04-04 The instrument is operating nominally. IOL ratios appear to be leveling off in the bluest orders.

2022-03-28 The instrument is operating nominally. IOL ratios appear to be leveling off in the bluest orders. There was an incident this weekend where the instrument was reading all zeros and the icc needed to be restarted.

2022-03-21 The instrument is operating nominally. IOL ratios appear to be leveling off in the bluest orders. There was an incident this weekend where the instrument was reading all zeros and the icc needed to be restarted.

2022-03-14 The instrument is operating nominally. IOL ratios are showing a very very slow improvement (or leveling off) in the bluest orders, still at moderate but acceptable levels.

2022-03-07 The instrument is operating nominally. IOL ratios are showing a very very slow improvement (or leveling off) in the bluest orders, still at moderate but acceptable levels.

2022-02-28 The instrument is operating nominally. IOL ratios are showing a very very slow improvement (or leveling off) in the bluest orders, still at moderate but acceptable levels.

2022-02-21 The instrument is operating nominally. IOL ratios are showing a very very slow improvement (or leveling off) in the bluest orders, still at moderate but acceptable levels.

2022-02-14 The instrument is operating nominally. IOL ratios are showing a very very slow improvement (or leveling off) in the bluest orders, still at moderate but acceptable levels.

2022-02-07 The instrument is operating nominally. IOL ratios are showing a very very slow improvement (or leveling off) in the bluest orders, still at moderate but acceptable levels.

2022-02-07 Theinstrument is operating nominally. IOL ratios are showing a very slow improvement (or leveling off) in the bluest orders, still at moderate but acceptable levels.

2022-02-05 Regained connection to the guider (ecamera). Unknown how the usb connection got into such a confused state. IOL ratios are showing a very slow improvement (or leveling off) in the bluest orders, still at moderate but acceptable levels.

2022-02-04 Lost connection to the guider (ecamera). Troubleshooting. IOL ratios are showing a very slow improvement (or leveling off) in the bluest orders, still at moderate but acceptable levels.

2022-01-31 The instrument is operating nomially. IOL ratios are showing a very slow improvement (or leveling off) in the bluest orders, still at moderate but acceptable levels.

2022-01-26 The instrument is operating nomially. IOL ratios are showing a very slow improvement in the bluest orders, still at moderate but acceptable levels.

2021-12-20 The instrument is operating nomially. IOL ratios are showing a very slow improvement in the bluest orders, still at moderate but acceptable levels.

2021-12-13 The instrument is operating nomially. IOL ratios are showing a very slow improvement in the bluest orders, still at moderate but acceptable levels.

2021-12-06 The instrument is operating nomially. IOL ratios are showing a very slow improvement in the bluest orders, still at moderate but acceptable levels.

2021-11-29 The instrument is operating nomially. IOL ratios are showing a very slow improvement in the bluest orders, still at moderate but acceptable levels.

2021-11-22 The instrument is operating nomially. IOL ratios are showing a very slow improvement in the bluest orders, still at moderate but acceptable levels.

2021-11-15 The instrument is operating nomially. IOL ratios are showing a very slow improvement in the bluest orders, still at moderate but acceptable levels.

2021-11-08 The instrument is operating nomially. IOL ratios are showing a very slow improvement in the bluest orders, still at moderate but acceptable levels.

2021-11-01 The instrument is operating nomially. IOL ratios are showing a very slow improvement in the bluest orders, still at moderate but acceptable levels.

2021-11-01 The instrument is operating nomially. IOL ratios are showing a very slow improvement in the bluest orders, still at moderate but acceptable levels.

2021-10-25 The instrument CCD is cold. IOL ratios are showing a very slow improvement in the bluest orders, still at low but acceptable levels. IOL ratios in the blue are at a peak value since spring of 2019.

2021-10-18 The instrument CCD is cold. IOL ratios are showing a very slow improvement in the bluest orders, still at low but acceptable levels. IOL ratios in the blue are at a peak value since spring of 2019.

2021-10-11 The instrument CCD is cold. IOL ratios are showing a very slow improvement in the bluest orders, still at low but acceptable levels. IOL ratios in the blue are at a peak value since spring of 2019.

2021-10-04 The instrument CCD is cold. IOL ratios are showing a very slow improvement in the bluest orders, still at low but acceptable levels. IOL ratios in the blue are at the peak values they were the past two years.

2021-09-27 The instrument CCD is cold. IOL ratios are showing a very slow improvement in the bluest orders, still at low but acceptable levels. IOL ratios in the blue are at the peak values they were the past two years.

2021-09-20 The instrument CCD is cold. IOL ratios are showing a very slow improvement in the bluest orders, still at low but acceptable levels.

2021-09-18 The instrument CCD is cold. IOL ratios are showing a very slow improvement in the bluest orders, still at low but acceptable levels.

2021-09-13: The instrument CCD is cold. IOL ratios are showing a very slow improvement in the bluest orders, still at low but acceptable levels.

2021-09-06: The instrument CCD is cold. IOL ratios are showing a very slow improvement in the bluest orders, still at low but acceptable levels.

2021-08-30: The instrument CCD is cold. IOL ratios are showing a very slow improvement in the bluest orders, still at low but acceptable levels.

2021-08-09: The instrument CCD is cold. IOL ratios are showing a very slow improvement in the bluest orders, still at low but acceptable levels.

2021-08-02: The instrument CCD is cold. IOL ratios are showing a very slow improvement in the bluest orders, still at low but acceptable levels.

2021-07-26: The instrument CCD is cold. IOL ratios have leveled off some but at a slightly higher level, still at low but acceptable levels.

2021-07-12: The instrument CCD is cold. IOL ratios have leveled off at low but acceptable levels.

2021-07-06: The instrument CCD is cold. IOL ratios have leveled off at low but acceptable levels.

2021-06-28: The instrument CCD is cold. IOL ratios are leveling off at low but acceptable levels.

2021-05-24: The instrument CCD is cold. IOL ratios have been steadily dropping over the past week.

2021-05-18: The instrument CCD is cold. IOL ratios will be monitored over the next few days more often to see if contamination returns.

2021-05-17: The instrument remains unavailable while we have the CCD warmed and the shield cold. We are attempting to increase the IOL ratio.

2021-05-14: IOL ratios dropped dangerously low over the past 48 hours. Attempting to correct by warming the CCD reservoir but keeping the shield cold. We have not decided at this time if to put it back on a vacuum pump.

2021-05-12: Instrument is available and operating nominally at this time.

2021-05-11: Completed instrument vacuum maintenance. Installed new vacuum valve and ion pump . Instrument should be cold by tomorrow morning.

2021-05-04: Instrument is undergoing normal maintenance

2021-04-19: Instrument has been operating nominally.

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.

2020-12-07: The instrument is operating nominally. IOL continues to slowly improve with colder ambient temperatures.

2020-11-30: The instrument is operating nominally.

2020-10-26: The instrument is operating nominally.

2020-10-19: The instrument is operating nominally.

2020-10-12: The instrument is operating nominally.

2020-10-04: The instrument is operating nominally.

2020-09-28: The instrument is operating nominally.

2020-09-04: The instrument is operating nominally.

2020-08-28: The instrument is operating nominally.

2020-08-17: The instrument is operating nominally.

2020-08-11: The instrument is operating nominally.

2020-08-04: The instrument is operating nominally.

2020-06-22: The instrument is operating nominally.

2020-06-20: The instrument is operating nominally.

2020-06-01: The instrument is operating nominally.

2020-04-06: The instrument is operating nominally.

2020-03-30: The instrument is operating nominally.

2020-03-23: The instrument is operating nominally.

2020-03-09: The instrument is operating nominally.

2020-03-02: The instrument is operating nominally.

2020-02-24: The instrument is operating nominally.

2020-02-17: The instrument is operating nominally.

2020-02-10: The instrument is operating nominally.

2020-02-03: The instrument is operating nominally.

2020-01-27: The instrument is operating nominally.

2020-01-13: The instrument is operating nominally.

2020-01-06: The instrument is operating nominally.

2020-01-03: The instrument is operating nominally.

2020-01-02: Most recent interorder ratio plot can be found here.

2019-12-16: The instrument is operating nominally.

2019-12-09: The instrument is operating nominally. The interorderlight is improving with cooler temperatures.

2019-11-04: The instrument is operating nominally. The interorderlight is improving with cooler temperatures.

2019-10-21: The instrument is operating nominally. The interorderlight is improving with cooler temperatures.

2019-10-14: The instrument is operating nominally. The interorderlight is improving with cooler temperatures.

2019-09-23: The instrument is operating nominally.

2019-09-09: The instrument is operating nominally. The interorderlight is leveling off with cooler ambient temperatures.

2019-08-26: The instrument is operating nominally although the interorderlight has been slowly degrading with time. .

2019-08-12: The instrument is operating nominally.

2019-08-05: The instrument is operating nominally.

2019-07-11: Subframes for the echelle guider should be restored and working. Have asked the observing specialists to please test.

2019-07-08: The instrument is operating nominally.

2019-05-16: Installed a new guide camera that is more sensitive. Currently subframes / windowing of guide frames is not working. A problem report ticket was filed. Consult withthe observing specialists in the event you have questions.

2019-05-16: The instrument is operating nominally.

2019-03-07: Could not find a mechanical problem with shutter. Bench tested fine. Not dirty. Action is good. Will test on the instrument tonight.

2019-03-06: Removed spectrograph shutter for cleaning and bench testing.

2019-03-01: The science shutter is sticking on occasion. Please check your calibrations and science frames to verify your data is good. The problem manifests itself as vertical streks in your spectra from bright lines. .

2019-02-18: The observing specialists have been reporting a sticky shutter for the main instrument. Please inspect your data carefully until we can confirm.

2019-01-02: The instrument is operating nominally.

2019-01-02: Most recent interorder ratio plot can be found here.

2018-12-10: There was a failure of the QTH power supply. Replaced.

2018-12-07: The science instrument is operational however there was a failure of the QTH white light lamp control circuitry that we still troubleshooting. Users will be unable to take internal QTH calibrations until this is fixed. ThAr calibrations are working fine. Replaced QTH bulb as part of the troubleshooting.

2018-12-03: The instrument has been operating nominally. Interorder light is slowly improving over the past 2 months.

2018-11-05: There was an inadvertant warming of the instrument this afternoon due to the nurse tank vent valve being left open the day before. The CCD warmed to +20C. It was cooled back down before scheduled observing A-Half and the instrument appears to be working nominally.

2018-10-15: The instrument has been performing nominally

2018-10-08: The IOL has been steadily dropping but seems to be leveling off as ambient temperatures are dropping. Otherwise the instruemnt has been performing nominally.

2018-09-11: The instrument has been operating nominally. The instrument was warmed and pumped to improve the IOL this summer with good results.

2018-04-02: The instrument has been operating nominally

2018-03-19: The instrument has been operating nominally

2018-02-05: No further readout issues reported.

2018-01-30: Same readout issue last night.

2018-01-29: Problems with the readout of the instrument last night. A reset of the saddlebag eventually resulted in restoring camera readout. Instrument is working now but this is noted here in case it repeats.

2018-01-24: Most recent interorder ratio plot can be found here.

2017-10-30: No change. Interorder light is still poor but stable. Contact observing staff if it is affecting your data.

2017-09-20: Interorder light has leveled off. If scattered light from a given order is appearing in other orders of your data, please report it right away to the observatory staff.

2017-09-13: Interorder light which is a measure of scattered light in the instrument from contamination is continuing to worsen. Users are advised to report any effect to their science to the APO staff. See the link below to the most recent IOL plots.

2017-08-31: It is back! Echelle is ready for on sky testing and science. We are slowly lowering temperature to the operating value. Contact the observing specialist for more information.

2017-08-22: Update: The camera readout is still intermittent. We have the saddlebag on the workbench in the lab and are attempting to track down the problem but with it being intermittent progress is slow. Ecamera is working however. Over shutdown we changed out the electronics boards effectively giving us a brand new slitviewer camera.

2017-07-08: Update: We are working with Dale Sanford and Connie Roskie to troubleshoot the readout electronics failure. We have experienced and found two additional failed components so far but the root cause is still ellusive. We appreciate users patience. The intermittent failure of the slit viewr camera is being discussed with Technicians at ANDOR. It is possible it will need to be returned for evaluation and repair.

2017-06-22: The science camera has had a failure where it will not properly read out images. We are troubleshooting but until corrected the instrument is down.

2017-06-21: Further investigation of the slitview camera mentioned on Monday has revealed that bias levels for the camera are zero. The camera is also running a few degrees warmer than its temperature setpoint. Darks are linear and the CCD is seeing light. It can be used for guiding. We are investigating if the lower than expected bias level is adjustable on the board from the manufacturer. There has not been a repeat of the corrupted (or partially elevated background levels on the left side of the chip) that was reported intermittently Thursday - Sunday nights. Report any occurances to the Observing Specialist.

2017-06-19: No change with the main instrument other than the IOL is slowly worsening as seen in the forementioned plots. There was an issue last Thursday night where ecamera (Slitviewer) was producing strange images. Likely due to a low level in the liquid cooling reservoir although that has not been determined as the actual cause. The reservoir was filled this morning. We will continue to monitor. Please report any weird performance issues to the observing specialists.

2017-06-12: IOL still dropping but it should not affect data according to Russet. The Interorderlight prior to 2014 was typically in the mid-teens and had little effect on science as far as was reported. The sudden drop in the measured value has caught our attention because it can change quite rapidly and we want to minimize the amount of time where the levels are down to the 'teens' in the red or blue. We will continue to monitor the IOL levels going into shutdown. The purpose of asking users to take 30 minute darks is to verify that there is no dark current present. So far even with the CCD running at -90C (-120C is the setpoint), we see neglible to no dark current. Most recent interorder ratio plots can be found here.

2017-05-30: Still running the CCD heater at full power. The blue IOL continues to be in a slow lowering trend but far enough away from what we have determine to be detrimental to science. Advise users to take 30 minute darks at the end of their run if possible.

2017-05-18: The instrument is available but running at a warmer temperature to slow contamination forming. Recommend, minimum of 1 dark exposure @ at least 15 minutes duration, 2-3 dark exposures to remove cosmic ray removal desired.

2017-05-03: Last night the observing specialists reported lower than normal IOL measurements indicating evidence that contamination was forming on the or near the CCD. After regular measurements throughout the night showing the problem was degrading rapidly it was decided to take the instrument offline and start to warm the camera. The instrument will be offline for another week to mitgate this disappointing development after servicing.

2017-05-01: Vacuum servicing complete. Ion pump was changed as part of the servicing work. IOL measurements look nominal after the CCD reached normal operating temperatures.

2017-04-19: Echelle is undergoing vacuum servicing. It is unavailable until May 1. This work includes installing a new ion pump.

2017-03-03: Most recent interorder ratio plot can be found here.

2016-10-24: Several reported failures of the echelle slitviewer camera over this past weekend. In most cases these seem to be during afternoon checkout when the first images were attempted for the day. Power ycles of the camera each time corrected the problems.

2016-08-01: A report that the QTH lamp may be nearing the end of its lifetime. Users should check their instrument flat fields and report any problems.

2016-04-04: No further reports on the intermittent slitviewer computer issues since December.

2015-08-01: There was an instance where the ICC crashed apparently because of a stuck cal mirror in the guider box. We have had issues with the dirvers for these motors before. The motor control software is quite antiquaited. It is possible there are no timeouts in the software or the timeout was never triggered due to a loss of signal. Therefore the higherlevel software led to a unstable condition and crashed. Recovery was not difficult. The motor was assisted into the proper position, and the ICC needed a restart. Will look for a repeat of the trouble and consider action at that time.

2015-01-26: There was one instance in the past month where the science detector produced an image of all zeros. A reboot of the ICC corrected this. Please report repeat of the problem to the Observing specialist or the Telescope Engineer. So far we do not anticipate this is a sign of inital failure of a component or subsystem.

2014-09-22: Continued monitoring of the interoder light ratios indicate good results from the warm-up and cooldown to reduce scattered light from contamination in the light path

2014-09-11: CCD is again cold and interorder light ratios in both red and blue (18 and 45 respectively) look good. Will continue to monitor ovver the next week.

2014-09-08: Warming the CCD camera given there is a short break in the science schedule.

2014-09-03: 00:13 Interorder light ratio: 8.2

2014-09-02: Interorder light update

date UT Interorder ratio Chip Temp (C) Notes

2014-08-19 11:57 6.7 -89

2014-08-20 00:33 7.0 -89

2014-08-20 01:30 raised set point further to -85

2014-08-20 22:02 7.4 -85

2014-08-20 23:00 lowered set point to -110

2014-08-21 04:00 7.0 -110

2014-08-21 12:39 7.1 -110

2014-08-22 00:00 6.9 -110

2014-08-23 19:28 6.9 -98

2014-08-24 23:40 7.1 -98

2014-08-20 heater raised to maximum current, chip temp floating

2014-08-26 11:45 7.2 -84

2014-08-27 00:00 7.2 -82

2014-08-28 00:17 7.3 -86

2014-08-30 7.5 -82

2014-08-31 7.6 -82

2014-09-01 8.0 -81

2014-09-02 00:30 8.2 -83

2014-08-22: Increased the chip heater voltage to maximum. The CCD will only warm to about -82C at this voltage. Hopefully running at this value will slowly reduce the contamination. We will be monitoring the interorder light values daily as a way of checking. Tests show that even at this level the dark current is negligible in 20 minutes and should not be a concern for users.

2014-08-20: Russet reports that the CCD is showing signs of contamination. Attempting to remove it by raising the heater temperatures.

date UT Interorder ratio

2014-08-15 00:54 15.3

2014-08-15 22:14 9.2

2014-08-16 21:46 7.4

2014-08-17 22:10 7.2

2014-08-19 00:47 7.0

2014-08-19 07:08 7.1

2014-08-19 11:57 6.7

2014-08-20 00:33 7.0

2014-08-14: Instrument is cold and available for science. Completed ion pump swap earlier in the week and vacuum pumpdown. The Observing Specialists did a full checkout in the evening.

2014-08-11: Vacuum servicing this week. Instrument is unavailable

2014-07-16: Big tank has been pumped down to a vacuum greater than 100 milliTorr

2013-07-17: Jon Holtzmann (holtz at nmsu.edu) reports that he finally has a good spectral line solution for the new ARCES grating. Please contact him for further details.

The new ARCES grating was successfully installed during 2012 summer shutdown. Do not use calibrations older than August 1, 2012. Ask Jon Holtzmann (NMSU) for the new iraf wavelength and dispersion solution files.

ARCES Users Guide Appendix B. Instrument History

2013-03-20: External driver circuit is working. Back in service.

2013-03-18: After multiple reports of shutter problems with the echelle, we believe we have narrowed the trouble down to an intermittent shutter driver circuit for the instrument. This circuit is not repairable. Ed Leon intends to build a custom driver circuit to replace this portion of the instrument controls. The new driver circuit will be built and tested today and tomorrow. It is our hope to have the instrument ready for science Tuesday evening.

2013-02-05: The echelle is again cold with a good vacuum. It still is unclear at this time the true cause of the vacuum failure and warmup. Some additional characterization testing still needs to be done tonight but it should be ready for use tomorrow night.

2013-01-28: The instrument warmed over the weekend. It is unclear at this time if it was a failure of the autofill system or a loss of vacuum. We are investigating and will pumping on it this week.

2012-11-29: Installed shorter cables. Saw improved performance in echelle cal mirror performance but hope to get further improvement from reduceing cable length further. Another cable is on order.

2012-11-09: Replacement cables arrived but want to schedule the next round of repairs until there is a break in the echelle schedule.

2012-11-05: We are trying a number of possible solutions for the calibration mirror. Software and various hardware solutions are proving difficult due to the age of the equipment and the lack of spares. Our next attempt will be to replace some of the more key cables in the system. Those are on order.

2012-09-20: We believe the problem with varing QTH lamps is related to a problem with the calibration mirror. We have changed the stepper controlling this mirror, inspected the driver board and have aligned calibration light path. We will continue to work on this problem. Replacing the stepper driver board will be next during next weeks engineering time.

2012-09-05: Reports of varying levels in the CuS (blue) Flats with no change in the unfiltered Qth Flats caused me to suspect the bulb is starting to fail. Changed out the bulb in the QTH lamp today.

2012-08-10: The new MR152 grating was installed and aligned over summer shutdown. Please be aware not to use old cals or wavelength solutions since the wavelengths in each order have shifted. Contact the Observing Specialists or the Telescope Engineer for more details.

2012-06-22: Replaced Red and Blue slitviewer filters with new ND4 and ND5 filters. User guide updated with more information on the ND filters.

2012-03-04: Echelle slitviewer masks fixed