R: Julian-Day number to Julian century

julianCenturyAnomaly {oce} | R Documentation

## 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)

### Arguments

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

### Value

Julian century since noon on January 1, 1900.

### Author(s)

Dan Kelley

### References

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

### See Also

Other things related to astronomy: `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")

[Package oce version 1.2-0 Index]