al-Zarqālah (493 H) said: Fajr is at 18 degrees.
His name is Abū Isḥāq Ibrāhīm ibn Yaḥyā al-Naqqāsh al-Zarqālī (al-Zarqālah) al-Tujibi, and he passed away in the year 493 of the Hijrah, which corresponds to the year 1100. The instrument maker and astronomer from Andalusia. His astronomical instruments and works would continue to be used for another 400 years. The great astronomer Nicolaus Copernicus cited from his works...