Milton Heifetz is an amateur astronomer, professor of neurosurgery, and inventor of 'The Precession of the Equinoxes' planisphere, now at the Harvard University Museum of Historical Scientific Instruments. It is now used to determine positions of the stars in ancient history and years in the future.
Wil Tirion is a Free Lance Uranographer and Graphic Designer. He is co-author of The Monthly Sky Guide, now in its seventh edition (Cambridge University Press, 2006).