sidereal

Documentation

Overview

Sidereal: Chapter 12, Sidereal Time at Greenwich.

Index

• func Apparent(jd float64) unit.Time
• func Apparent0UT(jd float64) unit.Time
• func Mean(jd float64) unit.Time
• func Mean0UT(jd float64) unit.Time

Examples

• Mean (A)
• Mean (B)

Functions

func Apparent

func Apparent(jd float64) unit.Time

Apparent returns apparent sidereal time at Greenwich for the given JD.

Apparent is mean plus the nutation in right ascension.

The result is in the range [0,86400). 计算格林威治瞬时视恒星时

func Apparent0UT

func Apparent0UT(jd float64) unit.Time

Apparent0UT returns apparent sidereal time at Greenwich at 0h UT on the given JD.

The result is in the range [0,86400). 计算格林威治0h UT视恒星时

func Mean

func Mean(jd float64) unit.Time

Mean returns mean sidereal time at Greenwich for a given JD.

Computation is by IAU 1982 coefficients. The result is in the range [0,86400). 计算格林威治 jd 时刻的瞬时平恒星时,化简结果至一天范围之内

Example (A)

// Example 12.a, p. 88.
jd := 2446895.5
s := sidereal.Mean(jd)
sa := sidereal.Apparent(jd)
fmt.Printf("%.4d\n", sexa.FmtTime(s))
fmt.Printf("%.4d\n", sexa.FmtTime(sa))

Output:

13ʰ10ᵐ46ˢ.3668
13ʰ10ᵐ46ˢ.1351

Example (B)

// Example 12.b, p. 89.
jd := julian.TimeToJD(time.Date(1987, 4, 10, 19, 21, 0, 0, time.UTC))
fmt.Printf("%.4d\n", sexa.FmtTime(sidereal.Mean(jd)))

Output:

8ʰ34ᵐ57ˢ.0896

func Mean0UT

func Mean0UT(jd float64) unit.Time

Mean0UT returns mean sidereal time at Greenwich at 0h UT on the given JD.

The result is in the range [0,86400). 计算格林威治 0h UT 平恒星时，并化简为单位为秒一天之内的值[0,86400).