 This was confirmed by al-Birūni, al-Marrākushī and al-Kāshī.Al-Khujandī used his device to measure the sun's angle above the horizon at the summer and winter solstices; these two measurements allow computation of the latitude of the sextant's location and the obliquity of the ecliptic.Ulugh Beg constructed a Fakhri Sextant that had a radius of 40.4 meters, the largest instrument of its type in the 15th century.