APPULDIS

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.

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