Sunday, October 24, 2010

where is all of the IQ data?

it turns out we were really fortunate to have gotten a few hours of good seeing early in our on-sky IQ testing. the seeing as measured by the upgraded Sutherland DIMM (now dubbed 'timDIMM') has been rather sub-par since the end of july:

the median seeing for this period (20-7 through 1-10) was 1.64" (corrected to zenith). previous studies of the SAAO site found median seeing values around 1" or slightly better. in fact, earlier in the year the SLODAR telescope measured a median total seeing of 1.08" during the period from mid-february until mid-april when it was shipped back to la palma. there is some question of the calibration of the timDIMM results compared to the same system using the old camera as well as compared to results from the other SAAO telescopes such as the 1.9-meter. much of that can be ascribed to its location and to its being very close to the ground, however. the timDIMM seeing has also agreed with the FWHM in SALT images fairly well so far. hopefully things will improve soon.....

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