Equatorial coordinates for celectial objects (ephemerides)

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Description

These functions compute equatorial coordinates of celestial objects at given day, their phase, position of the limb, distance from earth and the magnitude.

Usage

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sun(jday = jd())
mercury(jday = jd())
venus(jday = jd())
mars(jday = jd())
jupiter(jday = jd())
saturn(jday = jd())
uranus(jday = jd())
neptune(jday = jd())
pluto(jday = jd())

Arguments

jday

Julian Day number

Details

The algorithms used here are fairly simple and not with top-accuracy.

Sun is assumed to be always on ecliptic and no eccentric anomaly is considered. The accuracy should be within 10s of right ascension and few minutes of declination.

Planets position are calculated without solving the Kepler Equation and considering perturbations, so the accuracy is similar.

Value

An object of class "eqc, apos, data.frame", containing a row for each day, and following columns:

ra

Right Ascension

d

Declination

phase

Percentage of bright area visible from Earth

angle

Angle between the limb and north-south equatorial axis

dist

Distance from Earth in AUs

size

Size in arcsecs

mag

Magnitude

Author(s)

Lukasz Komsta

Examples

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options(latitude=51.25,longitude=22.5)	# Lublin, Poland
j=jd(length=30)				# Next 30 days
sun(j) 					# Equatorial position
as.hoc(sun(j),j)			# Horizontal position at current time