Analyzing the method of Hindi Circle for Determining the Direction of mosque's Qibla (Case Study: Isfahan Jame mosque)

Kaaba known as Qibla and the focus point of Muslim people is of paramount importance. Many scientists in the field of mathematics, astronomy and geography throughout the Islamic world tried to find the exact methods and procedures to determine the direction of Qibla. One of these methods is Hindi Circle used to determine Qibla of mosques. Most often the scientists, scholars and astronomers gathered at the time of a mosque construction and determined the mosque orientation by means of drawing Hindi circle. Hindi Circle is based on the sun movement and the resulted data of the horoscope. To better determination of the issue and sufficient knowledge of Hindi Circle method, Isfahan Jame mosque among Iranian-Islamic mosques have been chosen to be studied. Following investigations on the deviation angle of Qibla in these mosques, it has been found that the orientation of the mentioned mosques does not comply with the real direction of Qibla and there is a deviation angle. The question here is that how this deviation is made in spite of the progresses Muslims made in determining Qibla. Did the methods of determining Qibla direction such as Hindi circle have low accuracy? In order to answer this question Hindi circle method was analyzed based on the coordinates and new and old data. Concerning the studies of some horoscopes and manuscripts, it was concluded that the coordinates and data are not the same in different periods and this is the main reason of deviation from the actual direction of Qibla. In addition more accurate results can be obtained if the Hindi Circle method is used at certain times of the year.