Abd al-Rahman al-Sufi and his book of the fixed stars: a journey of re-discovery

Al-Şūfı's Book of the Fixed Stars, dating from around AD 964, is one of the most important medieval Arabic treatises on astronomy. This major work contains an extensive star catalog, which lists star co-ordinates and magnitude estimates, as well as detailed star charts. Other topics include descriptions of nebulae, colors of stars and Arabic folk astronomy. Al-Şūfı's book was based on Ptolemy's classical work called the Almagest which was written around A.D. 137. Al-Şūfı updated Ptolemy's stellar longitudes from A.D. 137 to 964 by adding 12 degrees and 42 minutes on Ptolemy's longitude values to allow for precession. However, it is surprising that at present no English translation of al-Şūfı's treatise exists. Therefore this is a Doctorate thesis which includes for the first time a complete English translation of the main parts of al-Şūfı's work as well as a detailed study of this important book. The main topics which have been discussed in this study include a brief biography on al-Şūfı, the extant manuscripts of al-Şūfı's treatise, the structure of the book and star catalogue, and the star maps and charts. One of al-Şūfı's innovations in charting the stars was the production of dual illustrations for each of Ptolemy's constellations. One illustration was as portrayed on a celestial globe. The other illustration was as viewed directly in the night sky. Al-Şūfı's contribution to astronomy was not only limited to writing this book but he was also instrumental in developing the science of astronomy for a very long time. He also contributed to the building of an important observatory in the city of Shiraz as well as constructing many astronomical instruments such as astrolabes and celestial globes. His influence reverberated throughout history reaching as far as the end of the 19th century. This study also includes a major finding which is al-Şūfı's magnitude unique 3-step intermediate magnitude system. Al-Şūfı identified more than one hundred new stars which he mentioned in his commentaries on the constellation but they were not included in the tables nor were they mentioned in the Almagest or any other ancient star catalogs.