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astro/basic/star.go

97 lines
2.6 KiB
Go

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package basic
import (
. "b612.me/astro/tools"
)
// StarHeight 星体的高度角
// 传入 jde时间、瞬时赤经、瞬时赤纬、经度、纬度、时区jde时间应为时区时间
// 返回高度角,单位为度
func StarHeight(jde, ra, dec, lon, lat, timezone float64) float64 {
// 转换为世界时
utcJde := jde - timezone/24.0
// 计算视恒星时
st := Limit360(SeeStarTime(utcJde)*15 + lon)
// 计算时角
H := Limit360(st - ra)
// 高度角、时角与天球座标三角转换公式
// sin(h)=sin(lat)*sin(dec)+cos(dec)*cos(lat)*cos(H)
sinHeight := Sin(lat)*Sin(dec) + Cos(dec)*Cos(lat)*Cos(H)
return ArcSin(sinHeight)
}
//StarAzimuth 星体的方位角
// 传入 jde时间、瞬时赤经、瞬时赤纬、经度、纬度、时区jde时间应为时区时间
// 返回方位角单位为度正北为0度数顺时针增加取值范围[0-360)
func StarAzimuth(jde, ra, dec, lon, lat, timezone float64) float64 {
// 转换为世界时
utcJde := jde - timezone/24.0
// 计算视恒星时
st := Limit360(SeeStarTime(utcJde)*15 + lon)
// 计算时角
H := Limit360(st - ra)
// 三角转换公式
tanAzimuth := Sin(H) / (Cos(H)*Sin(lat) - Tan(dec)*Cos(lat))
Azimuth := ArcTan(tanAzimuth)
if Azimuth < 0 {
if H/15 < 12 {
return Azimuth + 360
}
return Azimuth + 180
}
if H/15 < 12 {
return Azimuth + 180
}
return Azimuth
}
//StarHourAngle 星体的时角
// 传入 jde时间、瞬时赤经、瞬时赤纬、经度、时区jde时间应为时区时间
// 返回时角
func StarHourAngle(jde, ra, lon, timezone float64) float64 {
// 转换为世界时
utcJde := jde - timezone/24.0
// 计算视恒星时
st := Limit360(SeeStarTime(utcJde)*15 + lon)
// 计算时角
return Limit360(st - ra)
}
// TrueStarTime 不含章动下的恒星时
func TrueStarTime(JD float64) float64 {
T := (JD - 2451545) / 36525
return (Limit360(280.46061837+360.98564736629*(JD-2451545.0)+0.000387933*T*T-T*T*T/38710000) / 15)
}
// SeeStarTime 视恒星时,计算章动
func SeeStarTime(JD float64) float64 {
tmp := TrueStarTime(JD)
return tmp + HJZD(JD)*Cos(Sita(JD))/15
}
func StarAngle(RA, DEC, JD, Lon, Lat, TZ float64) float64 {
//JD=JD-8/24+TZ/24;
calcjd := JD - TZ/24
st := Limit360(SeeStarTime(calcjd)*15 + Lon)
H := Limit360(st - RA)
tmp2 := Sin(H) / (Cos(H)*Sin(Lat) - Tan(DEC)*Cos(Lat))
Angle := ArcTan(tmp2)
if Angle < 0 {
if H/15 < 12 {
return Angle + 360
} else {
return Angle + 180
}
} else {
if H/15 < 12 {
return Angle + 180
} else {
return Angle
}
}
}
func StarRiseTime(jde, ra, dec, lon, lat, height, timezone float64, aero bool) (float64, error) {
return 0, nil
}