oce (version 0.9-20)

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 Meese (1982 equation 15.1). The example reproduces the example provided by Meeuse (1982 example 15.a), with fractional error 3e-8.

Usage

julianCenturyAnomaly(jd)

Arguments

jd

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

Value

Julian century since noon on January 1, 1900.

References

Meeus, Jean, 1982. Astronomical formuae for Calculators. Willmann-Bell. Richmond VA, USA. 201 pages

See Also

Other things related to astronomy: eclipticalToEquatorial, equatorialToLocalHorizontal, julianDay, moonAngle, siderealTime, sunAngle

Other things related to time: ctimeToSeconds, julianDay, numberAsHMS, numberAsPOSIXct, oce.as.POSIXlt, 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")