A Study of the Seeing at the Weihai Observatory of the Shandong University

The one-meter equatorial optical telescope at the Weihai Observatory of the Shandong University was installed in June 2007, and since then it has been in commission. The value of seeing is one of the most important parameters for ground-based astronomy and the full widths at half maximum (FWHM) of stellar images can be used to indicate the seeing condition. In order to estimate the seeing condition of the Weihai Observatory, we processed all the observational data of the observatory in 2008 and 2009 to derive the values of FWHM automatically by an IRAF batch-processing procedure. In general the values of FWHM of stellar images are contributed from instrumental defraction, tracking errors, defocus, dome seeing, and so on. They may be larger than the seeing values obtained by a differential image motion monitor (DIMM), but they reflect the overall image quality of observations.We study all seeing data in these two years and analyze the correlation between the meteorological data and the seeing data. The results show that the median value of seeings (FWHM) at the Weihai Observatory is 1.69 arcsec and the typical seeing (FWHM) ranges from 1.2 arcsec to 2.0 arcsec. The best observing seasons are spring and autumn, and the observational condition in winter is also good. Temperature is the dominant meteorological factor for the fluctuation of seeing, perhaps because the air temperature gradient from the inside to the outside of the telescope dome triggers troublesome turbulence eventually causing large fluctuation of seeing.