NAME:
  lstlim
 PURPOSE:   (one line only)
  Compute the LST range for time of observation
 DESCRIPTION:
 CATEGORY:
  Astronomy
 CALLING SEQUENCE:
  lstlim,ra,dec,answer,rlst,slst,quiet=quiet
 INPUTS:
  ra  - RA of target (J2000) in radians or as a sexigesimal string
  dec - Declination of target (J2000) in radians or as a sexigesimal string
 OPTIONAL INPUT PARAMETERS:
 KEYWORD INPUT PARAMETERS:
  AMCRIT - airmass at start and stop of LST range (default=2.5)
  QUIET - flag if set will suppress printed output (echo of RA,Dec; the
            lst string, answer, and the length of time above the limit in
            hours)
 OUTPUTS:
  answer - formatted string of the start and ending local sidereal time
             to the nearest minute
  rlst   - local sidereal time at the time of rising (2.5 airmasses)
  slst   - local sidereal time at the time of setting (2.5 airmasses)
 KEYWORD OUTPUT PARAMETERS:
 COMMON BLOCKS:
 SIDE EFFECTS:
 RESTRICTIONS:
  Only works for Lowell Observatory right now.  Airmass limit is hard-coded.
 PROCEDURE:
 MODIFICATION HISTORY:
  2004/04/13 - Marc W. Buie, Lowell Observatory, first very rough version.
  2004/10/26, MWB, added AMCRIT and some input validation.
  2008/04/08, MWB, modified formatting of printed output.