This client is based on the JPL solar system ephemerides and the StarLink 'slalib' function set. The ephemeris file must cover the time range for which positions are to be extracted, and the leap-second and UT1 offset files must be updated periodically from IERS Bulletin A . The two ephemeris files, DEc200 and DEc403, found in the above directories currently span the years 1990 to 2010.
Some requests return a glish record with more than one named member, as described below.
The astrometric position is the direction of the line between the observer's position at the specified time and the position of the object at the time the light began its journey, i.e. the object's position at the specified time less the light travel time. This is the location of the object relative to a background of stars plotted in J2000 coordinates. Recognized, case-insensitive values are Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. Returns the observer's radial velocity component with respect to the specified object as a fraction of the speed of light. Recognized, case-insensitive values are Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto.