| Abu Ali al-Hassan al-Marrakushi | |
| Native Name: | الحسن المراكشي |
| Native Name Lang: | ar |
| Birth Date: | fl. late 13th century |
| Era: | Islamic Golden Age |
| Main Interests: | Mathematics, astronomy |
| Major Works: | (Collection of the Principles and Objectives in the Science of Timekeeping) |
Abu Ali al-Hassan al-Marrakushi (Arabic: الحسن المراكشي; late 13th century) was a Magreb astronomer and mathematician from the Kingdom of Morocco . He was especially important in the field of trigonometry and practical astronomy. He wrote (Collection of the Principles and Objectives in the Science of Timekeeping), a treatise on spherical astronomy and astronomical instruments. The first part was translated into French by the orientalist and astronomer during the early 19th century, and published after Sédillot's death. The treatise, which was written in Cairo between 1276 and 1282, is regarded as the most complete source to have survived about medieval Islamic astronomical instruments.
The crater Al-Marrakushi on the Moon is named after him.