New Light on the Main Instrument of the Samarqand Observatory

The observatory of Ulugh Beg, erected in Samarqand in the 1420s, represents the culmination in the development of astronomical observatories in the Islamic world. After its rediscovery and excavation in the early twentieth century there have been several attempts to reconstruct its appearance and explain how it worked in detail, based on archaeological finds and the analysis of relevant manuscripts. A new look at illustrated copies of an important manuscript provides new, hitherto unmentioned details to the understanding of this instrument. Based on previous reports, we have created a virtual reconstruction of the observatory and the new version of the instrument, from which we have gained new insights.