oce (version 1.8-3)

julianCenturyAnomaly: Convert Julian-Day-Number to Julian Century

Description

Convert a Julian-Day number to a time in julian centuries since noon on January 1, 1900. The method follows Equation 15.1 in Reference 1. The example reproduces the Example 15.a of the same source, with fractional error 3e-8.

Usage

julianCenturyAnomaly(jd)

Value

Julian century since noon on January 1, 1900.

Arguments

jd

a julian day number, e.g. as given by julianDay().

Author

Dan Kelley

References

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

See Also

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

Other things related to time: ctimeToSeconds(), julianDay(), numberAsHMS(), numberAsPOSIXct(), secondsToCtime(), unabbreviateYear()

Examples

t <- ISOdatetime(1978, 11, 13, 4, 35, 0, tz = "UTC")
jca <- julianCenturyAnomaly(julianDay(t))
cat(format(t), "is Julian Century anomaly", format(jca, digits = 8), "\n")