Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1780549 | NRIAG Journal of Astronomy and Geophysics | 2016 | 7 Pages |
Abstract
Twilight observations were carried out by naked eye in the period (2010–2012) for north Sinai (Lat. 31°4′N, Long. 32°52′E) where the background is desert, and for Assiut (Lat. 27°10′N, Long. 31°10′E) in the period (2012–2014) where the background is agricultural land. The purpose of these observations is to calculate the depression of the sun below the horizon at which the normal eye can discriminate the dawn (morning white thread) for two sites. The results indicated that this discrimination takes place at vertical sun depression angles, Do = 14.61° and 13.665° at Sinai and Assiut respectively.
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Astronomy and Astrophysics
Authors
A.H. Hassan, I.A. Issa, M. Mousa, Yasser A. Abdel-Hadi,