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

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: ɛ = 1.065″ in the V band. The characteristic seeing reduced to unit air mass, ɛ {_/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 ɛ {_/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 .