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	USAT --- A Unix compatible satellite tracking package

				Version 1.0

This is a package of programs and subroutines for tracking satellites.

The routines that produce the geocentric satellite positions are C versions
of the NORAD satellite ephemeris programs described in doc/spacetrk.tex.
These routines were converted to C and put under the Revision Control
System (RCS).  All these routines generate nearly identical geocentric
coordinates as given in the examples in doc/spacetrk.tex with the exception
of sdp8.  A careful investigation of the sdp8 routines has not found any
reason for the discrepancies.

The routines that convert the geocentric satellite positions to topocentric
positions are a modified version of Stephen L. Moshier's Astronomical 
Almanac package V5.1 (see the READMEs in the almanac directory). 

The Makefile in this directory will make all necessary routines in the
subdirectories.  Currently, any changes made with this Makefile should
also be made to the Makefiles in the subdirectories (to be corrected
in a future version of this software).  The Makefile is designed to be 
used with gmake.  The following executables are made:

almanac		Essentially Stephen L. Moshier's almanac program. Generates
		the position of the Sun, Moon, planets, etc for a given
		date along with rises, sets, transits, and many other bits
		of information.

bsat		An interactive satellite ephemeris generator.  Will generate
		coordinates for all the satellites in a two line element
		set file between given times at a given interval.

isat		Another interactive satellite ephemeris generator.  Will
		only do a ephemeris of the first satellite in a two line
		element set file.  Basically used to test the various NORAD
		satellite ephemeris programs.

plotgen		Generates a GNUPLOT command file for plotting the results
		of the sunsat program.

sawsat		An interactive program that searches a two line element set 
		file for satellites that approach within a given radius of
		a given ra and dec, for a given time period.  Can be used
		to identify satellites or to see if any satellites enter a
		given field of interest during a specific time.

sunsat		A batch program used to find satellites that approach
		within 1.5 degrees of the Sun and to generate 1 second
		ephemerides of those approaches.

In addition, the get-tles C-shell script is used to update the two line
element set files and to run sunsat on a subset of these files.

In order to run any of the programs, the local site information must be 
contained in either a ~/.site.ini file or a ./.site.ini file.  The
.site.ini file here is for Sunspot, New Mexico, USA.  As the parallax
corrections used to generate the topocentric satellite positions are often
tens of degrees, a accurate .site.ini file is a must.

These routines were compiled by gcc 2.3.3 under SUNOS 4.1.2.  I would
appreciate any information regarding compilation using different compilers
and different operating systems.  In addition, I would appreciate any
information concerning the accuracy of any predictions (I will boldly state
here that with limited use, the accuracy appears to be better than .1
degree).  Any other comments or suggestions are welcome.

Selected file/directory descriptions are given below:

.site.ini	The site description file.
Filelist	A list and brief description of files under RCS.
RCS		The RCS directory.
README		This file.
almanac		The directory containing the modified astronomical almanac
		routines originally written by Stephen L. Moshier.
doc		Miscellaneous documentation.
for		Fortran listings of the NORAD satellite ephemeris code.
h		Header files.
lib		Compiled library files.
tle		Contains two line element set files.

Craig Gullixson 18 May 1993.

Craig A, Gullixson
Sr. Research Associate

National Solar Observatory/ Sacramento Peak
P.O. Box 62
Sunspot, New Mexico 88340-0062

(505) 434-7088