Abu-Mahmud Khujandi

Abu Mahmud Hamid ibn al-Khidr al-Khujandi^[1] (known as Abu Mahmood Khujandi, al-khujandi or Khujandi, Persian: ابومحمود خجندی, c. 940 - 1000) was a Muslim Transoxanian astronomer and mathematician born in Khujand (now part of Tajikistan) who lived in the late 10th century and helped build an observatory, near the city of Ray (near today's Tehran), in Iran.