oce (version 1.7-8)

julianCenturyAnomaly: 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 reference 1 equation 15.1. The example reproduces the example provided by reference 1 example 15.a, 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

• 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")