NAME: 
  sspos
 PURPOSE: 
  Interactive program for generating solar system body ephemerides.
 DESCRIPTION:
  Interactive front-end for EPHEM.  Given object code (format described
    in EPHEM), this will compute positions and give local circumstances
    of the object.  Reads the current time from the system clock which
    may or may not be accurate.

  All output is printed on the screen.

 CATEGORY:
  Astronomy
 CALLING SEQUENCE:
 INPUTS:
 OPTIONAL INPUT PARAMETERS:
 KEYWORD INPUT PARAMETERS:
  TIME    - optional time [y,m,d,h,m,s] for positions
  AMCRIT  - Critical airmass for rise/set times.
  OBSFILE - Override on file name where observatory codes are to be found.
  OBSCODE - Integer Marsden code of the observatory, default 688 - Anderson Mesa
  APO     - Flag, if set, enables a special output mode for Apache Pt. Obs.
  DT      - If set will enable a special mode.  This value is the update
              frequency in seconds and the program will enter an infinite
              loop and printout the ephemeris information at this rate.
              The only way out is to ^C and interrupt.  You'll have to clean
              up the mess by hand afterward.  This value is limited to
              a maximum of 60 seconds.  If you give a larger value it will
              be reset to 60.  The default is -1 for the normal interactive
              mode.
 OUTPUTS:
 KEYWORD OUTPUT PARAMETERS:
 COMMON BLOCKS:
 SIDE EFFECTS:
 RESTRICTIONS:
  This procedure requires an external ephemeris computation engine that
    is accessed through pipe I/O.  The external commands are getinfo and
    geteph.
 PROCEDURE:
 MODIFICATION HISTORY:
  1994/04/11 - Initial version written by Marc W. Buie, Lowell Observatory.
  1995/05/03 - Added TIME keyword
  1995/09/10 - Fixed bug that causes program to crash for objects that never
               rise or set
  1996/12/27 - MWB, added interactive 'T' time set option.
  1997/03/05 - MWB, added FILE and OBSCODE keywords
  2001/03/22, David Tucker, changed obsfile support
  2001/04/18, MWB, changed systime call.
  2001/04/20, MWB, changed to support new geteph/ephem
  2002/09/09, MWB, added support for string obscode values
  2010/04/29, MWB, added APO keyword
  2013/02/15, MWB, added DT keyword and made some cosmetic changes