1a: Software Acronym:
	ODPPS

1b: Short Title:
	O Division Planetary Position Software

2: Author:
	Andrew P. Porter, porter@s1.gov; 
		Lawrence Livermore National Laboratory,
		O Division, Mail Stop L-276,
		Livermore, CA 94550 

3: Software Completion Date:
	December 1994

4: Brief Description:
	ODPPS reads and interprets a modified ascii version of 
	the Jet Propulsion Laboratory's planetary ephemeris,
	printing ecliptic barycentric and equatorial geocentric positions.
	It can also generate positions from orbits given in 
	_The Explanatory Supplement to the Astronomical Almanac_ (1992).
	JPL ephemeris data files for some years in original 
	and translated O Division format are included.  

5: Method of Solution:
	From the ephemeris, cartesian coordinates of the planets
	are calculated from chebyshev series.  
	Alternatively, planetary positions are calculated
	in the usual way from Keplerian orbits.
	Apparent place corrections are applied as per the Almanac, Section B.
	An executable for conversion of ascii to binary data files is provided,
	and an executable to create catalogs of data contained in the data files.  

6: Computers for which the software is written:
	It has been tested on a Sun Sparcstation running Unix 
	and on a 486 AT clone running Linux.  

7: Operating system for which the software is written:
	Unix and the Gnu C compiler; it should make on any platform with gcc.  

8: Programming Languages used:	
	C (mostly) and Fortran (one subroutine).
	The Fortran can be bypassed. 

9: Software Limitations:
	The ephemeris data files are large; about 2.8 Mb per ten years of data.
	Retrieval of data from ascii files can be slow.  
	
10: Unique features of the software:	
	The data files in translated format are reader-friendly,
	with comments identifying which dates and body the chebyshev
	polynomial coefficients are for; otherwise they
	are identical to the original JPL data file.

	The subroutine library will provide ecliptic barycentric 
	or geocentric equatorial positions for other code the user 
	may wish to write; the library of Keplerian orbit functions
	is of general applicability.

	(None of this is very unique; it is just convenient, and code
	to do the same things is available in somewhat different form, 
	in greater generality and in Fortran, from JPL or the Naval Observatory.)

11: Related Software:
	The Naval Observatory Vectorial Astronomy Software (NOVAS) package
	is excerpted in one routine, and used as model in some others;
	JPL's NAIF package is related, but of somewhat different form,
	and much greater power and generality.

	Further ephemeris data files could be added from JPL sources, 
	but they would have to be translated into O Division format.  
	(The code in ./convert may or may not succeed in doing that.)  

12: Other Programming or Operating System Information and Restrictions:
	The code is too large to compile with a DOS C compiler.
	The package has not been tested under DOS.

	The code is contained in a .tar file, which unpacks into five
	directories: ./docs (documentation); ./include (header files);
	./sources (*.c, *.f, makefile); ./progs (*.c, makefile);
	and ./convert/*.c (code to break up and translate the JPL ephemeris
	files into O Division format files).  The executables are in ./progs; 
	the subroutine library sources are in ./sources.  
	See general instructions in ./docs.

	The code in ./convert is shaky; it worked once, with the
	de/le-402 ephemeris, and produced the O Division format
	ascii data files supplied with ODPPS.  
	It may not work with any other JPL ephemeris.  

13: Hardware requirements:
	A system capable of running gcc with enough memory to hold the 
	compiled code (700k) plus whatever memory the compiler needs. 

	It has been tested on a Sun Sparcstation and a 486 AT clone
	with 8 Mb of memory running Linux. 

14: Time requirements: 
	the executable "fastplan", calculating positions from Keplerian orbits, 
	takes seconds at most on a 486-66; "planets", calculating positions
	from ephemeris data files, can take noticeably longer if the data 
	files are ascii and must be searched in their entirety.  
	Access of binary format ephemeris data files can require only seconds.  

15: References:
	Documentation supplied with the package is in the ./docs directory.
	The main references are the _Astronomical Almanac_, the _Explanatory
	Supplement to the Astronomical Almanac_ (1992), R. M. Green's 
	_Spherical Astronomy_, and your favorite orbital mechanics text.
	More references are contained in ./include/hnav.h.

	The JPL ephemerides, source of the data files, were generated at JPL
	by numerical integration; see refs in ./include/navconst.h.  

16: Categorization and Keywords:
	a: Subject Classification Code:
		S; Z.

	b: Keywords:
		Cartesian coordinates: data library: 
		Equations of motion: Interpolation: 
		NASA codes: Numerical data: Numerical solution:
		Polynomials: 

		Planetary coordinates: planetary data: 
		de/le-200 ephemeris: de/le-402 ephemeris: 
		UNIX computers: Kepler's equation: 
		Apparent Place Calculation: 
		Chebyshev Polynomials: