HPlanetarium is an astronomy software for HP calculators, provided under a free license (the GNU Public license). HPlanetarium has many features and can be installed on most of HP calculators series: HP39, HP40, HP48, HP49 and HP50. The HPlanetarium GUI is in English, and a French version is available.
HPlanetarium is a planetarium with many features. It can draw a sky map with main planets and stars. You can move, zoom and unzoom this map very quickly (nearly instantaneously). Many planets' properties can be displayed (equatorial coordinates, horizontal coordinates, heliocentric coordinates, geocentric ecliptic coordinates, elongation, phase, magnitude, diameter, rise time, transit time and set time). HPlanetarium can also show what the Moon looks like, the position of Jupiter's satellites, and compute the sidereal time. Provided that your calc is linked to a telescope (Autostar and LX200), you can point this latter.
HPlanetarium can also use computing routines of other programs. By now, the only supported programs are Ephe written by Jean Philippe Eimer and AstroLib written by Robert H. Parry.
An User RPL command for using the internal computing routines of HPlanetarium is also provided, so that you can write your own extensions.
HPlanetarium is a free software. The source code is then provided. Please read the COPYING file for more details about the GNU Public license.