Percy
Percy is an interactive computer program which provides ephemeris and
geometrical event information about solar system objects. These objects
include the Sun, major planets and their natural satellites, comets, and
asteroids.
Percy performs four primary functions :
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Locates time spans during which complex geometric constraints are satisfied.
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Graphically displays a field of view from any vantage point.
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Generates text reports of solar system phenomena.
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Generates ephemeris files.
Percy, named after Percival Lowell, and a companion program, Clyde, named
after Clyde Tombaugh, were originally developed by the Jet Propulsion Laboratory
(JPL) under contract to NASA Goddard Spaceflight Center and the Space Telescope
Science Institute (STScI). STScI took over the development and maintenance
of Percy and Clyde in 1992. Since then, extensive modifications and improvements
have been made including a port from VAX/VMS to Unix. The functionality
of Clyde was added to Percy, so Clyde is no longer supported. Currently,
Percy is only supported on the Sun Sparc Solaris platform.
Internally, Percy uses the SPICELIB software library supplied
by JPL's Navigation and Ancillary Information Facility (NAIF). SPICELIB
provides many lower level services, calculations, and ephemeris file utilities.
Percy was originally developed specifically for Hubble Space Telescope
(HST) observation planning and scheduling. While it contains some HST specific
features, Percy should be useful for almost any ground or spacecraft based
observing system.
Last updated: 02 June 2005