Ali ibn Ridwan

Ali ibn Ridwan was born in Giza in 988 and worked in Cairo under the Fatimid caliphs as a physician, astrologer and astronomer. Largely self-taught, he became chief physician and wrote many medical works, including a celebrated polemic against the Baghdad physician Ibn Butlan. His commentary on Ptolemy's Tetrabiblos survives in dozens of Arabic manuscripts and was translated into Latin.

In 1006, as a young man, he observed a new star in the southern sky in the constellation now called Lupus. In his commentary on the Tetrabiblos he described it as two and a half to three times the size of Venus, lighting the ground with a brightness a little more than a quarter of moonlight, low on the horizon.

Modern astronomers identify this with SN 1006, a supernova also recorded in China, Japan, Iraq, Yemen and at the Swiss abbey of St. Gall. Its remnant is still visible to radio and X-ray telescopes. Ibn Ridwan's account is the most detailed surviving eyewitness description.