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ENR CTIO Blanco 4-m 2012-12-03

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Date: 
Monday, December 3, 2012
Telescope: 
CTIO Blanco 4-m
Submitter: 
Liz Buckley-Geer
Observer Support: 
Francisco Javier Rojas
Night Assistant: 
Leonardo Paredes
Problems: 
The relative humidity in the electronics crates 1-3 started to rise. The dew point got to about 12 degrees which is uncomfortably close to the point at which we would get condensation on the cooling water pipes in the crates (the chiller water runs at 15 degrees). Javier Rojas spoke to Juan about the problem. We opened the back of the imager to examine the hoses which are supposed to be flowing the dry nitrogen. We discovered there was no hose connected to the system to complete the loop so no air was flowing. Juan spoke to Herman Cease and it appears that the dry gas flow was actually never hooked up for some reason! It is odd that this has not been a problem before but maybe the combination of temperature and outside humidity tonight was optimal to trigger a problem (the humidity got to 70% earlier in the evening). After consulting with Tom Diehl the temporary solution is to raise the Neslab chiller temperature to 18 degrees to allow us to keep taking data at least for tonight.
Comments: 
We also ran some guider tests at the start of the night. We learned the following: a) running the sextractor based Guider from the ram disk did not reduce the jitter. Santi’s initial analysis showed the same behavior we saw in the past. Whatever causes the variations in sextractor processing time doesn’t seem to be caused by disk IO. b) Santi’s new guider sort of worked in the PyGuide only mode but finding guide stars was not as reliable as with the sextractor based guider (this is just our impression – a more careful study is needed). We noticed a very long interval (30 seconds or more) between the first image (2kx2k) and the start of the guider sequence. It is amazing that this worked at all after just a day of programming but as is it is not yet usable. We tried lowering the threshold to 3 (sigma) detection but this did not make a noticeable difference and there also seems to be a coding problem setting this variable. c) We also tried the combined mode that uses sextractor for guide star selection and pyguide for the centroids measurement. This did not work – no crash but for some yet unknown reason no guide stars were found in this mode. There were also periods where the guider was oscillating back and forth. They forced us to to give up on the deep z-band supernova field. There were also large guider excursions on some images while on the survey field at RA = 65 deg DEC = -55 deg.
Conditions: 
General Conditions
Temperature Max: 
15.00
Temperature Min: 
12.00
Humidity Max: 
78
Humidity Min: 
50
Wind Speed Max: 
10.00
Wind Speed Min: 
0.00
Comment: 
None.
1st Quarter
Clouds: 
Clear
Seeing Value: 
0.00
Seeing Variability: 
0
Seeing Source: 
CTIO Seeing monitor
Sky : 
0
2nd Quarter
Clouds: 
Clear
Seeing Value: 
1.00
Seeing Variability: 
0
Seeing Source: 
Other
Sky: 
0
3rd Quarter
Clouds: 
Clear
Seeing Value: 
1.00
Seeing Variability: 
0
Seeing Source: 
Other
Sky: 
0
4th Quarter
Clouds: 
Clear
Seeing Value: 
1.20
Seeing Variability: 
0.2
Seeing Source: 
Other
Sky: 
0
Program: 
Proposal: 
2012B-0003
Target of Oportunity: 
No
Time Observed: 
4.5
Time Engineering: 
1.5
Time lost technical: 
1.25
Time lost weather: 
0.0
Time lost other: 
0.0
Description: 
DES SV
Primary Investigator: 
Josh Frieman
Email: 
frieman@fnal.gov
Institution: 
Fermilab
Instrument: 
CTIO 4m DECam
Organization: 
NOAO
Total Program Time: 
7.25
Total Times Time Observed Time Engineering Time lost technical Time lost weather Time lost other Total Program Time
2012-12-03 4.5 1.5 1.25 0.0 0.0 7.25