الخلاصة

In the domains of Astronomy and Geodesy, and according to the different hypotheses dependent on distribution of atmospheric condition , many versions of the computing formulae of Atmospheric refraction have been published, and a lot of versions of Atmospheric refraction tables have also come out to get important and more accurate information. In this study a new mathematical model has been proposed to calculate the Astronomic refraction by using least square fitting method and other mathematical approximations with utilizing data that was collected by the weather link station accompanying Kufa Astronomical Observatory, during the interval 1\5\2011 to 30\4\2012. In this model Astronomic refraction in arc sec, when: P in hPa, T in 0C , and the altitude in deg; also is applicable for altitude range 10 - 300, zenith angle from 600 to 900, in comparison with the previous Astronomic refraction models. Thus, the Astronomic refraction value, in arc sec, is presented at weather conditions T0=100C, P0=1005 hpa, and zenith angles 600,650,700,750,800,850 equals to 100.985, 122.504, 154.770, 208.515, 315.891, 637.192 respectively. The results obtained from the study have been compared with other researchers which was in perfect agreement.