SOFTWARE TO TRANSFORM EPHEMERIS FILES AVAILABLE

February 2, 2006

SOFTWARE TO TRANSFORM EPHEMERIS FILES AVAILABLE

Since January 29th, 2006 the International GNSS Service (IGS) began
making its precise ephemeris files available only in the SP3-c format.
For the time being, NGS will continue to make available the precise orbits
in both SP3-a (files with extension *.sp3) and SP3-c format (files with
extension *.sp3c).

If anyone needs to convert a file from SP3-c format to the older SP3-a
format, there is a Windows NT/2000/XP executable to do this available at:

        http://www.ngs.noaa.gov/CORS/Utilities/NT/sp3csp3a.exe

There is also source code written in the C computer language that people can
compile and use on other computer platforms like Linux, Unix, etc. This
C source code is available at:

        http://www.ngs.noaa.gov/CORS/Utilities/Source/sp3csp3a.c

This sp3csp3a program requires command line arguments; it can be run in a
DOS command prompt window on a PC. The typical usage is:
sp3csp3a.exe input.sp3c output.sp3a

The input and output filenames can be anything you wish. There is
also a Perl script that can be used to convert from SP3-c back to
SP3-a format, it is available at:

        ftp://ftp.gfz-potsdam.de/pub/igsacc/product/SOFTWARE/sp3c_2_sp3a/unix

and at:

        ftp://ftp.gfz-potsdam.de/pub/igsacc/product/SOFTWARE/sp3c_2_sp3a/windows

The SP3-c format description can be found on the IGS website at:

        http://igscb.jpl.nasa.gov/newformats.html

Read related information posted in the Newsletter January 27, 2006.