ʿAbu al-Ḥasan Alāʾ al‐Dīn bin Alī bin Ibrāhīm bin Muhammad bin al-Matam al-Ansari known as Ibn al-Shatir or Ibn ash-Shatir (Arabic: ابن الشاطر; 1304–1375) was an Arab astronomer, mathematician and engineer. He worked as muwaqqit (موقت, timekeeper) in the Umayyad Mosque in Damascus and constructed a sundial for its minaret in 1371/72. Source: Wikipedia (en)