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.help rdplan Jun99 "Slalib Package"
.nf
SUBROUTINE slRDPL (DATE, NP, ELONG, PHI, RA, DEC, DIAM)
- - - - - - -
R D P L
- - - - - - -
Approximate topocentric apparent RA,Dec of a planet, and its
angular diameter.
Given:
DATE d MJD of observation (JD - 2400000.5)
NP i planet: 1 = Mercury
2 = Venus
3 = Moon
4 = Mars
5 = Jupiter
6 = Saturn
7 = Uranus
8 = Neptune
9 = Pluto
else = Sun
ELONG,PHI d observer's east longitude and geodetic
latitude (radians)
Returned:
RA,DEC d RA, Dec (topocentric apparent, radians)
DIAM d angular diameter (equatorial, radians)
Notes:
1 The date is in a dynamical timescale (TDB, formerly ET) and is
in the form of a Modified Julian Date (JD-2400000.5). For all
practical purposes, TT can be used instead of TDB, and for many
applications UT will do (except for the Moon).
2 The longitude and latitude allow correction for geocentric
parallax. This is a major effect for the Moon, but in the
context of the limited accuracy of the present routine its
effect on planetary positions is small (negligible for the
outer planets). Geocentric positions can be generated by
appropriate use of the routines slDMON and slPLNT.
3 The direction accuracy (arcsec, 1000-3000AD) is of order:
Sun 5
Mercury 2
Venus 10
Moon 30
Mars 50
Jupiter 90
Saturn 90
Uranus 90
Neptune 10
Pluto 1 (1885-2099AD only)
The angular diameter accuracy is about 0.4% for the Moon,
and 0.01% or better for the Sun and planets.
See the slPLNT routine for references.
Called: slGMST, slDT, slEPJ, slDMON, slPVOB, slPRNU,
slPLNT, slDMXV, slDC2S, slDA2P
P.T.Wallace Starlink 26 May 1997
Copyright (C) 1997 Rutherford Appleton Laboratory
Copyright (C) 1995 Association of Universities for Research in Astronomy Inc.
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.endhelp
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