palRdplan

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palRdplan

Approximate topocentric apparent RA,Dec of a planet

Description:

Approximate topocentric apparent RA,Dec of a planet, and its angular diameter.

Invocation

void palRdplan( double date, int np, double elong, double phi, double

*

ra, double

*

dec, double

*

diam );

Arguments

date = double (Given)

MJD of observation (JD-2400000.5) in TDB. For all practical purposes TT can be used instead of TDB, and for many applications UT will do (except for the Moon).

np = int (Given)

Planet: 1 = Mercury 2 = Venus 3 = Moon 4 = Mars 5 = Jupiter 6 = Saturn 7 = Uranus 8 = Neptune else = Sun

elong = double (Given)

Observer’ s east longitude (radians)

phi = double (Given)

Observer’ s geodetic latitude (radians)

ra = double $*$ (Returned)

RA (topocentric apparent, radians)

dec = double $*$ (Returned)

Dec (topocentric apparent, radians)

diam = double $*$ (Returned)

Angular diameter (equatorial, radians)

Notes:

Unlike with slaRdplan, Pluto is not supported.
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 palDmoon and eraPlan94.

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