Jan Franco (active 1586–1611) was a physician, mathematician and astronomer who compiled almanacs.
He was born in the village of Eersel in the Duchy of Brabant and studied medicine at the University of Leuven.
[1] As he had studied both medicine and mathematics, he was asked to calculate the ephemerides, for purposes of medical astrology.
From 1612 to 1621 Arnout Coninx and his widow were selling almanacs based on Franco's drafts but completed for publication by his son, Jan Franco jr., and by Johannes Regius.
[3][4] At least as late as 1616 almanacs prepared by others were being sold on the strength of their association with Franco.