Convert Ecliptical Coordinate to Equatorial Coordinate

Convert from ecliptical to equatorial coordinates, using equations 8.3 and 8.4 of reference 1, or, equivalently, equations 12.3 and 12.4 of reference 2.

Usage

eclipticalToEquatorial(lambda, beta, epsilon)

Arguments

lambda

longitude, in degrees, or a data frame containing lambda, beta, and epsilon, in which case the next to arguments are ignored

beta

geocentric latitude, in degrees

epsilon

obliquity of the ecliptic, in degrees

Value

A data frame containing columns rightAscension and declination both in degrees.

Details

The code is based on reference 1; see moonAngle() for comments on the differences in formulae found in reference 2. Indeed, reference 2 is only cited here in case readers want to check the ideas of the formulae; DK has found that reference 2 is available to him via his university library inter-library loan system, whereas he owns a copy of reference 1.

References

• Meeus, Jean. Astronomical Formulas for Calculators. Second Edition. Richmond, Virginia, USA: Willmann-Bell, 1982.

• Meeus, Jean. Astronomical Algorithms. Second Edition. Richmond, Virginia, USA: Willmann-Bell, 1991.

See also

Other things related to astronomy: angle2hms(), equatorialToLocalHorizontal(), julianCenturyAnomaly(), julianDay(), moonAngle(), siderealTime(), sunAngle(), sunDeclinationRightAscension()

Author

Dan Kelley, based on formulae in references 1 and 2.