NAME:
  ephcheck
 PURPOSE:
  Compare a set of astrometry observations against an ephemeris.
 DESCRIPTION:

 CATEGORY:
  Astrometry
 CALLING SEQUENCE:
  ephcheck,objcode,obs,astfile
 INPUTS:
  objcode - Standard object code for ephemeris to check against.  See EPHEM.
  obs     - Standard observatory code (see RdoBSCOD)
 OPTIONAL INPUT PARAMETERS:
  astfile - Raw astrometry file to read and compare to ephemeris, default
              is "objcode.ast"  where the input objcode is first stripped of
              the leading prefix character.
 KEYWORD INPUT PARAMETERS:
  PLOTIT - Flag, if set will cause the information to be plotted as well.
  LOWESS - If provided and greater than zero, will cause a lowess plot
             to be superimposed on the plots and the smoothing width will
             be set to the value given (in days).  This keyword is ignored if
             PLOTIT is not set.

 OUTPUTS:
  All information is printed to screen.
 KEYWORD OUTPUT PARAMETERS:

 COMMON BLOCKS:

 SIDE EFFECTS:

 RESTRICTIONS:

 PROCEDURE:

 MODifICATION HISTORY:
  1998/01/14, Written by Marc W. Buie, Lowell Observatory
  2007/10/31, MWB, added PLOTIT keyword and added some printed output
  2007/11/20, MWB, added LOWESS keyword
  2011/02/02, MWB, minor formatting tweak to protect against short file names
  2013/09/03, MWB, added ephemeris error information to the printout
  2016/06/01, MWB, allow string input for observatory code