Nabonassar (also Nabonasser, Nabu-nasir, Nebo-adon-Assur or Nabo-n-assar) was a king of Assyria who founded the Chaldean and Babylonian kingdom. He became a king in 747 BC, and ruled 14 years (until 732 BC). The Greek astronomer Claudius Ptolemaeus started an era, i.e. a start point for chronological calculations, at New Years day in the Egyptian calendar of that year: at Wednesday February 26, 747 BC (in our proleptic Julian calendar). At this day the Nabonassar era (AN - Anno Nabonassari) began, which was used by Ptolemy and later astronomers, but not by the Babylonians themselves.
