MDM Observatory 2.4m Telescope Observing Report for 2015 Dec 26

Observer(s): Y. Jeon, Y.-K. Sheen, D. Park
Institution(s): Seoul National Univsersity

Instrument: OSMOS/B

Worked for 10 hours (most of the night)
Conditions were Non-Photometric most of the night.
Problems were encountered, see the separate trouble report for details.

Seeing and Weather:
   Beg: Seeing 1.9 arcsec, Patchy Clouds, Winds High
   Mid: Seeing 3.3 arcsec, Clear, Winds High
   End: Clear, Winds High

Observing Summary:

We started with partially cloudy sky
and it got clear later. 
We had a smooth observation until 2AM. 
After 2AM, the ‘disperser times out’ problem occurred and 
we could not solve the problem. 
We described details in a trouble report. 
We closed the dome at 4AM. 


During observation, we had some problems. 

1. arc spectra from Xe lamp 
a) We could not get any emission lines 
from Xe lamp at the first exposure image with a long exposure time. 
b) We moved to Ar lamp arc, then we got emission line signals. 
c) Then, we moved to Xe lamp again, and we could get emission lines. 
We also had the same problems in 12/21. 
and we cannot figure out why. 

2.  Arc spectra taken during daytime shows solar continuum and absorption lines. 
During daytime, we open the dome louvers and took some arc images. 
In this case, we saw a high background similar to the sky flat images. 
Also, the arc image had some absorption features. 
I suspect that the sun light shines in through a path for arc light. 
Night time arc images do not have that features. 

3. We lost the dome pointing during observation. 
We reset the Dome AZ encoder following below:
http://mdm.kpno.noao.edu/Manuals/mdmguide_current.html#dgotchas
At the end of the observation, we encountered same problem and 
did the same procedure again. 


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Submitted on 2015 Dec 27 [5:04:40]