Seeing and atmospheric extinction at Mt. Maidanak observatory from observations with the 1.5-m AZT-22 telescope

Abstract

We have determined the realistic seeing of the 1.5-m AZT-22 telescope of the Mt. Maidanak Observatory (Astronomical Institute, Uzbek Academy of Sciences) using more than 20 000 CCD frames with stellar images in the UBV RI bands acquired in 1996–2005: e = 1.065″ in the V band. The characteristic seeing reduced to unit air mass, e med V (M(z) = 1), is 0.945″. We derived color equations for the CCD detectors used with the telescope. Atmospheric-extinction coefficients in different photometric bands were also determined. The mean V -band atmospheric extinction is 0.20 m ± 0.04 m . The time needed for the conditions to settle, in the free atmosphere as well as inside the telescope dome, is 2–2.5 hours after the end of astronomical twilight. For nights with e med V > 0.9″, we find a persistent difference between the seeing found at this telescope and measured simultaneously with a differential image motion monitor, amounting to ∼0.1 m .