Abstract

This article aims to test a new method of dating optico-astronomical manuscripts, using Ibn al-Haytham’s Epistle on the Shape of the Eclipse as the test case. This work is selected because of indications that its diagrams are based on reality. After clarifying the observation conditions, an astronomical ephemeris is applied to sift through the eclipses that occurred during Ibn al-Haytham’s life throughout the area he is believed to have sojourned. Next, the remaining eclipses are sorted by computing the image projection. The results show that Ibn al-Haytham’s Epistle is likely to have reported the partial solar eclipse of 28 Rajab A.H. 380/21 October 990 in Baṣra. Because this exercise is primarily the test of a new method, this finding should be regarded as a tentative outcome, pending further information.