Below is a brief summary of the April Arizona LBC run.

We observed with the LBCs on the LBT for six nights from Apr 6 to Apr 11, 2008. The Arizona observing team consisted of Xiaohui Fan, Ben Weiner (first half of the run), and Linhua Jiang, Dave Sand (second half of the run), assisted by supporting astronomer Marco Pedani and operators Aaron Ceranski and David Gonzalez Huerta, John Hill also logged in remotely to help out every night.

Out of the four nights: the first three nights were very productive, with mostly clear skies (one photometric night), reasonable seeing (between 0.7 and 1.3", averaged around 1.0") and well behaved telescope/camera. The last three nights all had a combination of high wind, poor seeing, high humidity and clouds. We didn't open much during the last three nights, and the data were not that useful even when opened.

We are continuing to execute our three highest ranked programs on dwarf galaxies, large disk galaxies and the Bootes deep field survey. We have also started to do a new program on the Extended Groth Strip survey program. Based on the original time allocations, the large disk galaxy program is completed, and both the dwarf galaxy and Bootes program have completed more than half of the OBs (with acceptable data).

This run was considerably smoother than our previous run (during which we lost about 20% of time due to telescope and camera failures). During the six nights, we lost virtually no time due to camera failures. One trick seemed to be that we rebooted everything, both the CMU and the desktop computers, right before the beginning of the night to clean up anything left over from the previous night. We also lost very little time due to telescope failures. The only noticeable problem with the slow recovery from a power failure on the mountain (but even that was shorter than the power failure we experienced during our Feb run). Therefore, the open shutter time during the time that we are open considerably increased.

We continued to struggle with guiding, especially for our high galactic latitude deep fields that lack bright stars, and during the periods when either there were cirrus or the seeing was bad. We didn't notice significant difference in this area from the last run; 10-20% of images (most in the blue) were still elongated. John Hill experimented on-the-fly active optics correction which seemed to improve the images when there were suitable stars on the tech chips. Note that the guiding issues are mostly associated with faint (or no) guide stars; without any real change of the system, the only way would be to adjust the OBs to have guide stars on the tech chips.

We also continued to spend more time than we would like in the beginning of the night with telescope focusing. But with more experiences, it seemed to be getting better than last time (although the seeing this run was worse, so focusing was slightly easier).

Many thanks to the LBTO staff. We will be back in late May for our last LBC run this semester.

Xiaohui Fan for the observers.

-- XiaohuiFan - 03 Jun 2008
Topic revision: r1 - 03 Jun 2008, XiaohuiFan
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