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.help planel Jun99 "Slalib Package"
.nf
SUBROUTINE slPLNE (DATE, JFORM, EPOCH, ORBINC, ANODE, PERIH,
: AORQ, E, AORL, DM, PV, JSTAT)
- - - - - - -
P L N L
- - - - - - -
Heliocentric position and velocity of a planet, asteroid or comet,
starting from orbital elements.
Given:
DATE d date, Modified Julian Date (JD - 2400000.5)
JFORM i choice of element set (1-3; Note 3)
EPOCH d epoch of elements (TT MJD)
ORBINC d inclination (radians)
ANODE d longitude of the ascending node (radians)
PERIH d longitude or argument of perihelion (radians)
AORQ d mean distance or perihelion distance (AU)
E d eccentricity
AORL d mean anomaly or longitude (radians, JFORM=1,2 only)
DM d daily motion (radians, JFORM=1 only)
Returned:
PV d(6) heliocentric x,y,z,xdot,ydot,zdot of date,
J2000 equatorial triad (AU,AU/s)
JSTAT i status: 0 = OK
-1 = illegal JFORM
-2 = illegal E
-3 = illegal AORQ
-4 = illegal DM
-5 = numerical error
Called: slELUE, slUEPV
Notes
1 DATE is the instant for which the prediction is required. It is
in the TT timescale (formerly Ephemeris Time, ET) and is a
Modified Julian Date (JD-2400000.5).
2 The elements are with respect to the J2000 ecliptic and equinox.
3 Three different element-format options are available:
Option JFORM=1, suitable for the major planets:
EPOCH = epoch of elements (TT MJD)
ORBINC = inclination i (radians)
ANODE = longitude of the ascending node, big omega (radians)
PERIH = longitude of perihelion, curly pi (radians)
AORQ = mean distance, a (AU)
E = eccentricity, e (range 0 to <1)
AORL = mean longitude L (radians)
DM = daily motion (radians)
Option JFORM=2, suitable for minor planets:
EPOCH = epoch of elements (TT MJD)
ORBINC = inclination i (radians)
ANODE = longitude of the ascending node, big omega (radians)
PERIH = argument of perihelion, little omega (radians)
AORQ = mean distance, a (AU)
E = eccentricity, e (range 0 to <1)
AORL = mean anomaly M (radians)
Option JFORM=3, suitable for comets:
EPOCH = epoch of perihelion (TT MJD)
ORBINC = inclination i (radians)
ANODE = longitude of the ascending node, big omega (radians)
PERIH = argument of perihelion, little omega (radians)
AORQ = perihelion distance, q (AU)
E = eccentricity, e (range 0 to 10)
4 Unused elements (DM for JFORM=2, AORL and DM for JFORM=3) are
not accessed.
5 The reference frame for the result is with respect to the mean
equator and equinox of epoch J2000.
6 The algorithm was originally adapted from the EPHSLA program of
D.H.P.Jones (private communication, 1996). The method is based
on Stumpff's Universal Variables.
Reference: Everhart, E. & Pitkin, E.T., Am.J.Phys. 51, 712, 1983.
P.T.Wallace Starlink 18 March 1999
Copyright (C) 1999 Rutherford Appleton Laboratory
Copyright (C) 1995 Association of Universities for Research in Astronomy Inc.
.fi
.endhelp
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