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arc
arc computes an ephemeris for GPS satellites from a set of initial
conditions.
arc is copyrighted by the Massachusetts Institute of Technology and the
University of California at San Diego. All rights are reserved.
OVERVIEW
arc computes or integrates the orbits of GPS satellites from an a
priori set of initial conditions called state vectors (i.e. the position,
velocity and radiation pressure scaling factors for each satellite at a single
epoch) using physical laws and standard models. The program uses an eleventh
order Adams-Moulton predictor-corrector to compute the positions and, if
requested, the derivatives of those positions required for an orbit
adjustment. Specially constructed for GPS, arc is capable of generating
an ephemeris accurate at the centimeter level. Of special note are the use of
appropriate point masses for the Sun and Moon, but a more complex model for
the Earth's gravitational field including the effect of the solid-earth tidal
bulge. The integrator time step is modified for satellites entering and
leaving to better account for the rapidly changing forces in these
transitions, and both the penumbra and umbra shadows are modelled. Several
recognized, standard models and parameters are available to represent the
physical universe and the GPS satellites.
INPUT FILES
- arc.inp - selection of arc models and
output parameters
- g_file - the satellite initial conditions
- svnav.dat - satellite physical attributes
- leap.sec - a list of leap seconds
- pole. - Earth orientation parameters
- ut1. - TAI - UT1 differences
- soltab. - solar ephemeris
- luntab. - lunar ephemeris
- nutabl. - nutation parameters
OUTPUT FILES
FILES USED IN THE EXAMPLES
- example.tgz - gzip'd, tar file of the
complete files uesd as examples in this documentation.
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January 14, 2000