Normalized Flats
After the recent NIRSPEC service, there is no sign of dewar ice absorption. The green curve is current.
Normalized Flats |
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Divided Flats |
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It's been 10 months since the NIRSPEC service. The water ice absorption is approaching 10-20%. We hope to service NIRSPEC in September which should clear this up. The current curve is purple.
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| Flat Images | Cuts |
Divided Flats |
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It's been 7 months since the NIRSPEC service. There does not appear to be significant water ice absorption. The current curve is purple.
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It's been 4 months since the NIRSPEC service. There does not appear to be significant water ice absorption. The current curve is purple.
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It's been 2 months since the NIRSPEC service. There does not appear to be significant water ice absorption. The current curve is purple.
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NIRSPEC was be taken offline August 14 - September 8 to warm the dewar and pump. This service has successfully removed the observable water ice from the dewar. The current curve is purple.
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15 months have passed since the NIRSPEC service. NIRSPEC will be taken offline for a warm and pump service between August 14 and September 9. We are looking to stay ahead of the ice.
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12 months have passed since the NIRSPEC service. MAGIQ was permanently installed in the NIRSPEC cal unit in March. It appears as though we are seeing the beginnings of water ice absorption within the dewar. Monitoring will continue, but we will likely warm & pump NIRSPEC in the fall.
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| Flat Images | Cuts |
Divided Flats |
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10 months have passed since the NIRSPEC service. During December and January, the cal unit was open for the MAGIQ installation pathfinder. All were wearing masks to avoid too much breathing on the window. There could be the beginnings of some absorption, but the window still looks good.
Normalized Flats |
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| Flat Images | Cuts |
Divided Flats |
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7 months have passed since the NIRSPEC service. The window still looks pretty clear.
Normalized Flats |
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Divided Flats |
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5 months have passed since the NIRSPEC service. The window still looks pretty clear
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4 months have passed since the NIRSPEC service. Maybe starting to see some ice absorption, but not too bad.
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| Flat Images | Cuts |
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2 months have passed since the NIRSPEC service. Everything looks fine.
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NIRSPEC was be taken offline March 7-28 to warm the dewar and pump. This service will test whether simply warming and pumping removes ice from the dewar window, or whether the window needs to be replaced.
Normalized Flats |
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| Flat Images | Cuts |
Divided Flats |
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NIRSPEC will be taken offline March 7-28 to warm the dewar and pump. This service will test whether simply warming and pumping removes ice from the dewar window, or whether the window needs to be replaced.
Normalized Flats |
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| Flat Images | Cuts |
Divided Flats |
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The NIRSPEC entrance window was replaced at the end of March 2006. No icemonitor data were taken until after the earthquake-induced power outage on 15 October 2006. In post-quake icemonitor data, the ice absorption looks similar to the 6 month absorption from the previous window. Compare to 2005 Aug 19 below.
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Divided Flats |
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After about 1 year of service, it seems the ice is returning to the NIRSPEC dewar window. Please see the images and cuts across those images below.
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During the recent NIRSPEC service to replace the cold heads, we also replaced the NIRSPEC dewar window.
Before and After |
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| Old window | New window |
2005 May 14 |
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| dark-subtracted flat | cut across the flat |
2005 May 14 Spectral Cuts |
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| Cut along spectral direction, approximately 50 pixels in from the left-hand side. |
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| Cut along spectral direction, approximately centered spatially |
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| Cut along spectral direction, approximately 50 pixels in from the right-hand side. |
2005 March 24 |
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| dark-subtracted flat | cut across the flat |
NIRSPEC has had some cooling woes of late. We will service NIRSPEC in early March and are trying to determine if we need to replace the entrance window at the same time.
The flat lamp intensity varies so the important comparison is the amount of absorption across the flat, not comparison of maximum intensity
2005 January 14 |
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| dark-subtracted flat | cut across the flat |
2005 Jan 14 Spectral Cuts |
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| Cut along spectral direction, approximately 50 pixels in from the left-hand side. |
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| Cut along spectral direction, approximately centered spatially |
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| Cut along spectral direction, approximately 50 pixels in from the right-hand side. |
During the week of 2004 November 15, the computer control for the K2 air conditioners failed. The dome temperature rose 5 degress C before the a/c was manually restarted. Warm temperatures can allow water to condense on the window and soon thereafter form ice.
2004 November 19 |
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| dark-subtracted flat | cut across the flat |
The NIRSPEC window was replaced during the June 2004 Service Mission. Recent L-band flat fields show the improvement.
2004 July 20 |
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| dark-subtracted flat | cut across the flat |
This was the last meaurement of the window before it was replaced in 2004 June.
2004 March 01 |
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| dark-subtracted flat | cut across the flat |