Primary author: Hari Nair <hari@alumni.caltech.edu>

With contributions from:
Richard Rognlie <rrognlie@gamerz.net> (Ancient and Hemisphere
projections)
Ian Turner <vectro@vectro.org> (Icosagnomonic projection)
Martin Pool <mbp@linuxcare.com> (Peters Projection)

The SGP4/SDP4 library is based on code written by Neoklis Kyriazis
(http://leonardo.spidernet.net/Copernicus/22420). 

The code to read JPL Digital Ephemeris files uses routines from Bill
Gray (http://www.projectpluto.com/jpl_eph.htm).