NAME:
  appuldis
 PURPOSE:   (one line only)
  Find the circumstances of an appulse between a star and a solar system object
 DESCRIPTION:
  Given the ephemeris
  The approximate time of the appulse must be within +/-30 minutes or this
    will fail.
 CATEGORY:
  Astronomy
 CALLING SEQUENCE:
  appuldis,objcode,obscode,jd,ra,dec,jdmin,sep
 INPUTS:
  objcode - Standard object code (see ephem.pro)
  obscode - Standard observatory code or a structure with the observatory
              information.
  jd      - Approximate time of appulse
  ra      - right ascension of the star, J2000
  dec     - declination of the star, J2000
 OPTIONAL INPUT PARAMETERS:
 KEYWORD INPUT PARAMETERS:
  ET      - Flag, if set, all times are in Ephemeris Time, default is UTC
              This is most important for the output.  You can get away with
              inputing either.
  VERBOSE - Flag, if set, prints information about event to terminal
  STARERR - Star position uncertainty (arcsec), default is 0.050 arcsec
 OUTPUTS:
  jdmin   - Time of the minimum separation
  sep     - Separation between star and object at jdmin (arcsec)
                 If you get a negative number it means the search was not
                 successful in finding a minimum near the input time.
 KEYWORD OUTPUT PARAMETERS:
  info - Anonymous structure with auxillary information about the object
            at the time of the minimum separation.
           objname - Full name/designation of object
           jd  - Time of close approach
           hv  - Absolute magnitude of object
           et  - Flag, set if time is ET
           minsep - separate at close approach time (arcsec)
           pa  - Position angle of object wrt star at minimum separation
           sun - Heliocentric distance of object
           earth - topocentric distance of object
           phang - phase angle (degrees)
           selong - solar elongation (degrees)
           melong - lunar elongation (degrees)
           mphase - Lunar phase
           kmscale - scale on plane of sky in km/arcsec
           oam    - Airmass of object at time of event
           oalt   - object elevation (degrees)
           oaz    - object azimuth, westward from south
           salt   - solar elevation (degrees)
           malt   - lunar elevation (degrees)
           speed - projected speed of object relative to the star (km/sec)
           rate  - projected speed of object ralative to the star (arcsec/hr)
           diam1  - Diameter of object assuming 5% albedo (km)
           diam2  - Diameter of object assuming 30% albedo (km)
           chord1 - Maximum occultation duration assuming a 5% albedo size
           chord2 - Maximum occultation duration assuming a 30% albedo size
           angsha - Position angle of track on the plane of the sky, E of N
           etime  - 1-sigma error in event time (seconds)
           etrack - 1-sigma error in cross-track position (km)
           coverage - Fraction of the 1-sigma cross track error that could
                         be covered if track is centered on network
           err    - 1-sigma ephemeris uncertainty for the object at the
                       time of the close approach
           errkm  - 1-sigma ephemeris uncertainty in km.
 COMMON BLOCKS:
 SIDE EFFECTS:
 RESTRICTIONS:
 PROCEDURE:
 MODIFICATION HISTORY:
  Written by Marc W. Buie, Southwest Research Institute, 2015/03/07
  2015/09/24, MWB, Added position angle output