Ibn Khaldun | Ibn Battuta | Husayn ibn Ali | Hasan ibn Ali | Ibn Hisham | Jābir ibn Hayyān | Ibn Ezra | Abraham ibn Ezra | Tariq ibn Ziyad | Ibn Battuta Mall | Ibn Arabi | Solomon ibn Gabirol | Ibn Saud | Ibn Hawqal | Ibn Ezra (disambiguation) | Abu Sufyan ibn Harb | Yusuf ibn Tashfin | Qazan Khan ibn Yasaur | Muhammad ibn Jarir al-Tabari | Imam Muhammad ibn Saud Islamic University | Ibn Khordadbeh | Ibn Abi Zar | Hisham ibn Abd al-Malik | Amrus ibn Yusuf | Akhnas ibn Shariq | Abu'l-Fazl ibn Mubarak | Abd al-Aziz ibn Musa | Zayyan ibn Mardanish | Ubayda ibn as-Samit | Sulayman ibn Abd al-Malik |
Abu Hamid Ahmed ibn Mohammed al-Saghani al-Asturlabi (meaning the astrolabe maker of Saghan, near Merv) was a Persian astronomer and historian of science.
During the reign of al-Ma'mun, and together with Khālid ibn ʿAbd al‐Malik al‐Marwarrūdhī, he participated in an expedition to the Plain of Sinjar to measure the length of a degree, or the circumference of the Earth.
Together with ʿAlī ibn ʿĪsā al-Asṭurlābī in 827, he measured at 35 degrees north latitude, in the valley of the Tigris, the length of a meridian arc and thus the Earth's circumference, getting a result of 40,248 km (or, according to other sources, 41,436 km).