THE DATE OF FOUNDATION OF AUGUSTA TAURINORUM (TORINO) BY CROSS-CHECKING ASTRONOMY, ARCHAEOLOGY AND GROMATICS.

The paper dates the foundation of the city Augusta Turinorum (Turin) by applying an interdisciplinary and cross-checking method that relies on astronomy, archaeology and philology. The foundation procedure employed in the Hellenistic/Roman time has been reconsidered after a careful reading of the texts of the gromatic treatises of Sextus Iulius Frontinus and Hyginus Gromaticus who inform us that, at some point, the decumanus was oriented following the Sun position at its rising and at its falling by means of a gnomon. Then, an accurate reconstruction of the sun motion and the local measurement conditions by computing algorithms for the True Sun and applying the gnomon theorem, so far never introduced for such studies, provide a range of reliable years in which the alignment of the decumanus (the urban axis of the city) and the course of the Sun occurred. Finally, with the help of historical criticism and of professional astronomical tools, and according to some peculiar historical and archaeological condition of Augusta Taurinorum, the foundation day results the 30th of January, with good chances for 9/8 BC, in concomitance with the celebration of the festival at the Ara Pacis in Rome, instituted by the Senate of Rome in honor of Pax and in order to celebrate the reditus of Augustus from Gaul and Spain. [ABSTRACT FROM AUTHOR]