PLATLON

Name

platlon

Purpose (one Line Only)

Compute viewing and illumination geometry for Pluto

Description

Calling Sequence

platlon,jd,elat,elon,slat,slon,polang,phang,earth,sun,elong

Inputs

jd - Julian date for the geometry calculation
(double precision, scalar or vector)

Optional Input Parameters

Keyword Input Parameters

ORBIT - String with name of Charon orbit solution to use, the default
is to use the most recent orbit. This default can change
as new orbits are added.
Currently supported:
'2012' - From AJ, 144, 15 (2012)
'2008' - From AJ, 135, 777 (2008)
'1997' - From Icarus, 125, 245 (1997)
EPH - Optionally, you can provide the ephemeris information. The default
is to compute geocentric circumstants at the input time. This
information should be a vector as would be returned from a
code=22 request: [ra,dec,xobj,yobj,zobj,xsun,ysun,zsun]. The
positions should all be in units of AU. The ra,dec should be
in radians. The positions are relative to the observer.

Outputs

elat - Latitude of the sub-earth point [radians]
elon - East longitude of the sub-earth point [radians]
slat - Latitude of the sub-solar point [radians]
slon - East longitude of the sub-solar point [radians]
polang - Position angle of Pluto's north pole, measured eastward from
north [radians]
phang - Solar phase angle (Sun-Pluto-Earth angle) [radians]
earth - Geocentric distance [AU]
sun - Heliocentric distance [AU]
elong - Solar elongation [radians]

Keyword Output Parameters

Common Blocks

Side Effects

This is a slow routine for vector calls. Some of the supporting routines
cannot handle vectorized input so each output value is computed in an
explicit loop.

Restrictions

Procedure

Modification History

2011/12/30 - Written by Marc W. Buie, Southwest Research Institute
code based on fortran routines written by David Tholen
2012/06/04 - MWB, fixed typo on 2012 orbit.
2013/06/06 - MWB, added elong output.
2015/05/25 - MWB, added EPH input keyword.