Ibn al-Shatir
Although Ibn al-Shatir's system was firmly geocentric (he had eliminated the Ptolemaic eccentrics), the mathematical details of his system were identical to those in Copernicus's "De revolutionibus". Furthermore, the exact replacement of the equant by two epicycles used by Copernicus in the "Commentariolus" paralleled the work of Ibn al-Shatir one century earlier. Ibn al-Shatir's lunar and Mercury models are also identical to those of Copernicus. Copernicus also translated Ptolemy's geometric models to longitudinal tables in the same way Ibn al Shatir did when constructing his solar model. This has led some scholars to argue that Copernicus must have had access to some yet to be identified work on the ideas of ibn al-Shatir. It is unknown whether Copernicus read ibn al-Shatir and the argument is still debated. A Byzantine manuscript containing a solar model diagram with a second epicycle, was discovered to have been in Italy at the time of Copernicus. The presence of this eastern manuscript containing the ideas of Islamic scholars in Italy provides potential evidence of transmission of astronomical theories from the East to Western Europe.