A decade long research by Moonsighting.com found that any fixed degree is not correct for Subh-Sadiq or disappearance of Shafaq. The Subh-Sadiq and Shafaq are functions of latitude and seasons (day number of the solar year). All collected observations from different latitudes were plotted against day number of the year. With curve-fit technique, moonsighting.com came up with a function of latitude and seasons. In 2007 independent Muslim scientists in Pakistan also confirmed that degrees fluctuate with seasons. For more infos see : http://www.moonsighting.com/