doc Create GAMIT g/tfile with partials from SP3 orbit file
doc

 sh_sp3fit


 Purpose      Obtain GAMIT g/tfile with partials from SP3 orbit file

 Input        Automatic:   sp3 filename, session.info, station.info 
              Interactive: sp3 filename, project name, date, models

 Note: If a session.info file is available in the current directory, the last record 
       in the session.info file is used to set the year and doy used for the g- and t-file.

 Output       G-file and (optionally) t-file fit to input SP3 file
              Summary of adjustments (sp3fit.fit) and rms values (sp3fit.rms)

 sh_sp3fit   -f sp3files [-o orbit-name] [-d year doy] [-i equator prec] [-r radmod] [-t] [-u]
  
   -f    sp3 file names (up to 3 allowed) 
   -o    4-char name for g/t-files; default = read from station.info header (orbit name), or
         taken from first 3 chars of input .sp3 file plus decade (ie igs9) if not given.
   -d    year and day--of-year (yyyy ddd); default = extracted from session.info, (if it exists),
         or the input .sp3 file if not given.  If two entries (yyyy ddd1 ddd2), then the fit
         extends from 0h on ddd1 through 24h on ddd2 (assume multiple sp3 files input)
         mark the start
   -i    inertial reference system for t-file; default = J2000 IAU76  
   -r    radiation-pressure model; default = BERNE    
   -t    integrate estimated initial conditions (g-file) to get new t-file; 
            default is to skip, deferring ARC to GAMIT batch run
   -u    exclude satellites with orbit accuracy exponents = 0, which denotes unknown accuracy

 To exclude satellites from the orbfit estimation. Create a file called svs_exclude.dat
 This file is free format and has the format, yr, doy, sv.  
 (Eg.  1994 033 16 ) - to exclude prn 16 from 1994 doy 033.
 An example svs_exclude.dat file containing unmodelable IGS satellites is given in ~/gg/tables

# by Peng Fang (pfang@ucsd.edu), Mar 96.  Last modified by R. King August 2003 to exclude SVs in multiday fit