NAME:
  fieldobs
 PURPOSE:
  Real-time display of where objects are in the sky
 DESCRIPTION:

 CATEGORY:
  Astronomy
 CALLING SEQUENCE:
  fieldobs,file,AMCRIT=amcrit,OBSFILE=obsfile,OBSCODE=obs
 INPUTS:
  file - List of objects (for file format see LOADSTARS) to display

 OPTIONAL INPUT PARAMETERS:

 KEYWORD INPUT PARAMETERS:
  AMCRIT  - Maximum airmass for plotted display (default = 2.5)
  DT      - Offset from UT clock in hours.  This is mostly for debugging
              purposes but may prove useful otherwise.
  OBSFILE - Location of observatory information file, default is
              /pub/sac0/elgb/data/obscode.dat
  OBSCODE - Observatory code, default = '688', Lowell Observatory

 OUTPUTS:

 KEYWORD OUTPUT PARAMETERS:

 COMMON BLOCKS:

 SIDE EFFECTS:

 RESTRICTIONS:

 PROCEDURE:

 MODIFICATION HISTORY:
  97/05/28, Written by Marc W. Buie, Lowell Observatory
  98/04/30, MWB, added some items to the plot.
  2001/03/19, David Tucker, changed use of rdobscod for new file handling.
  2001/04/18, MWB, changed systime call
  2002/09/09, MWB, added support for string obscode values
  2017/12/24, MWB, fixed minor bug for the amount of time shown to sunset
                     during the first half of the day (while the Sun is
                     still ascending)