You are here: Foswiki>PartnerObserving Web>ArizonaQueue>FebSummary (21 Jul 2009, NormCushing)Edit Attach
0. Summary:

Overall a productive run, and certainly way beyond my (modest) expectations. Weather was good; we observed all six nights; had good (<=0.5") seeing often. Telescope/Camera loss is about 25%, shutter open efficiency is about 60%. A fair amount of science data taken, although we are still looking into what fraction suffered from guiding problems.

The team: Fan/Jiang, Sand/Herbert-Fort/Nelson covered three nights each. Lots of help from Hill/Kuhn/Thompson and the TOs.

1. Overall statistics:

Total Hours (between twilights): 62 hours Lost to Weather: 6 hours Total Usable Hours: 56 hours Lost to Telescope/Dome (approximate): 6 hours Lost to Camera (approximate): 9 hours Total Hours PartnerObserving: 41 hours (73% of Usable Time) Total Shutter Open Time: 23 hours (41% of Usable Time)

2. PartnerObserving Conditions:

Seeing: 3 good nights (0.4 - 1.2"), two OK nights (1.0 - 2.0") and one poor night (1.5 - 3"). Two photometric nights; 3 nights mostly clear; one night partly cloudy

3. Progress on Programs:

Dwarf Galaxy (EdO): about 10 hours of OB done Bootes (Fan): about 10 hours of OB done NGC galaxy (Zaritsky): about 2 hours of OB done SN+GRB poor seeing backup (Milne): about 1 hour of OB done

Not clear if all data are good quality. Guiding (both blue and red) is a major issue, and that might affect 30% or more of all images. I suspect a fraction of the OBs need to be redone.

4. Three highlihgts:

(1) We were able to get as good as 0.4" seeing, and for long period of time, 0.5" seeing, in Y band, and 0.6" in r.

(2) We were able to track and guide, without major complaints from telescope/camera, at the end of night when Bootes is transiting at 88.5 deg elevation, which only slightly trailed but still gives 0.6" images.

(3) One area didn't give us as much trouble as it used to is the focusing and mage analysis. Most cases it coveraged after two interations; and the expected seeing from lbcfpic is close to what we ended up getting. We only needed to adjust focus maually on average once every night. Refocusing after 30 min is still a good idea, and sometimes you can as long as 1 hour.

5. Major Problems:

Telescope: it seems that it often takes longer than expected to get the telescope ready at the beginning of the night, even when the telescope was handed over early in the afternoon. Almost all loss due to telesope happened due to the first few hours of the night; e.g., a power outrage took ~3 hours to recover.

Camera: major issue is guiding. Blue guiding has been poor, red guiding is better, but not perfect either. Adjusting guiding parameters helped little, suspect something deeper. Other main sources of loss are blue temperture read failure (requires 10 min to recover each time); and red filter wheel issue. The focus offset file was incorrect; it has been fixed in Y band, but engineering time is needed to refine it. At the best (0.4") seeing, it is also obvious that there is some sphereical aberration in the camera which indicates lens need to be further adjusted. I am also somewhat puzzled by the fact the blue seeing never got much better than 1" for the run (although when the red is 0.5", we happened to be mostly observing in U); I don't know if this is guiding or optical.

6. Comments:

Two impressions/suggestions:

(a) Needs of quality engineering time. I don't see any major obstacles for efficient observing (saving the guiding issue which I just don't understand). However, there are large number of minor issues any of which will cause 5-20 min loss of observing time when happens, but none happens very frequently. To debug needs lot of time; but during science observing, observers are more than happy to just press on and the process of solving them takes even longer. Also, some of the problems we see -- focus, possible LBC optics issue -- can only be tested and improved in very good conditions, and so far the engineering/commissioning time didn't have those good conditions.

(b) Needs of better coordinating engineering and night observing. What I see is that 80% of the problem happened during the first 3-4 hours of the night, as if both the telescope and the camera need a few hours to warm up to a stable state. The day crew is handing the telescope over at a reasonable time based on my past experience, and I think the needs to commission Greogian instruments are so great that we can not cut what they need during the day. However, maybe there are ways to start camera functions (and maybe telescope function if not any safety concern) earlier to warm up the system, such as exercising changing filter, taking many baises during the afternoon (in a way similar to people usually take dome flat in the afternoon). This may (may not) get us an earlier start on camera side and not interfering with important engineering activities.

-- XiaohuiFan - 03 Jun 2008
Topic revision: r2 - 21 Jul 2009, NormCushing
This site is powered by FoswikiCopyright © by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding Foswiki? Send feedback