// Apparent0UT returns apparent sidereal time at Greenwich at 0h UT
// on the given JD.
//
// The result is in seconds of time and is in the range [0,86400).
func Apparent0UT(jd float64) float64 {
j0, f := math.Modf(jd + .5)
cen := (j0 - .5 - base.J2000) / 36525
s := base.Horner(cen, iau82...) + f*1.00273790935*86400
n := nutation.NutationInRA(j0) // angle (radians) of RA
ns := n * 3600 * 180 / math.Pi / 15 // convert RA to time in seconds
return base.PMod(s+ns, 86400)
}
// Apparent0UT returns apparent sidereal time at Greenwich at 0h UT
// on the given JD.
//
// The result is in the range [0,86400).
func Apparent0UT(jd float64) unit.Time {
j0, f := math.Modf(jd + .5)
cen := (j0 - .5 - base.J2000) / 36525
s := unit.Time(base.Horner(cen, iau82...)) +
unit.TimeFromDay(f*1.00273790935)
n := nutation.NutationInRA(j0) // HourAngle
return (s + n.Time()).Mod1()
}
// Apparent returns apparent sidereal time at Greenwich for the given JD.
//
// Apparent is mean plus the nutation in right ascension.
//
// The result is in seconds of time and is in the range [0,86400).
func Apparent(jd float64) float64 {
s := mean(jd) // seconds of time
n := nutation.NutationInRA(jd) // angle (radians) of RA
ns := n * 3600 * 180 / math.Pi / 15 // convert RA to time in seconds
return base.PMod(s+ns, 86400)
}
// 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).
func Apparent(jd float64) unit.Time {
s := mean(jd) // Time
n := nutation.NutationInRA(jd) // HourAngle
return (s + n.Time()).Mod1()
}