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package star
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import (
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"errors"
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"math"
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"time"
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"b612.me/astro/basic"
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)
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var (
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ERR_STAR_NEVER_RISE = errors.New("ERROR:极夜，星星在今日永远在地平线下！")
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ERR_STAR_NEVER_DOWN = errors.New("ERROR:极昼，星星在今日永远在地平线上！")
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)
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// Constellation
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// 计算date对应UTC世界时给定Date坐标赤经、赤纬所在的星座
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func Constellation(ra, dec float64, date time.Time) string {
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jde := basic.Date2JDE(date.UTC())
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return basic.WhichCst(ra, dec, jde)
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}
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// MeanSiderealTime UTC 平恒星时
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func MeanSiderealTime(date time.Time) float64 {
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return basic.MeanSiderealTime(basic.Date2JDE(date.UTC()))
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}
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// ApparentSiderealTime UTC真恒星时
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func ApparentSiderealTime(date time.Time) float64 {
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return basic.ApparentSiderealTime(basic.Date2JDE(date.UTC()))
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}
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// RiseTime 星星升起时间
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//
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// date, 世界时（忽略此处时区）
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// ra，Date瞬时赤经
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// dec，Date瞬时赤纬
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// lon，经度，东正西负
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// lat，纬度，北正南负
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// height，高度
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// aero,是否进行大气修正
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func RiseTime(date time.Time, ra, dec, lon, lat, height float64, aero bool) (time.Time, error) {
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var err error
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if date.Hour() > 12 {
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date = date.Add(time.Hour * -12)
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}
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jde := basic.Date2JDE(date)
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_, loc := date.Zone()
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timezone := float64(loc) / 3600.0
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riseJde := basic.StarRiseTime(jde, ra, dec, lon, lat, height, timezone, aero)
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if riseJde == -2 {
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err = ERR_STAR_NEVER_RISE
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}
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if riseJde == -1 {
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err = ERR_STAR_NEVER_DOWN
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}
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return basic.JDE2DateByZone(riseJde, date.Location(), true), err
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}
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// DownTime 星星升起时间
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//
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// date, 世界时（忽略此处时区）
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// ra，Date瞬时赤经
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// dec，Date瞬时赤纬
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// lon，经度，东正西负
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// lat，纬度，北正南负
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// height，高度
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// aero,是否进行大气修正
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func DownTime(date time.Time, ra, dec, lon, lat, height float64, aero bool) (time.Time, error) {
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var err error
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if date.Hour() > 12 {
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date = date.Add(time.Hour * -12)
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}
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jde := basic.Date2JDE(date)
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_, loc := date.Zone()
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timezone := float64(loc) / 3600.0
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riseJde := basic.StarDownTime(jde, ra, dec, lon, lat, height, timezone, aero)
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if riseJde == -2 {
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err = ERR_STAR_NEVER_RISE
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}
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if riseJde == -1 {
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err = ERR_STAR_NEVER_DOWN
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}
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return basic.JDE2DateByZone(riseJde, date.Location(), true), err
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}
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// HourAngle 恒星时角
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// 返回给定Date赤经、经度、对应date时区date时刻的太阳时角（
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func HourAngle(date time.Time, ra, lon float64) float64 {
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jde := basic.Date2JDE(date)
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_, loc := date.Zone()
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timezone := float64(loc) / 3600.0
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return basic.StarHourAngle(jde, ra, lon, timezone)
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}
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// Azimuth 恒星方位角
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// 返回给定Date赤经赤纬、经纬度、对应date时区date时刻的恒星方位角（正北为0，向东增加）
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func Azimuth(date time.Time, ra, dec, lon, lat float64) float64 {
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jde := basic.Date2JDE(date)
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_, loc := date.Zone()
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timezone := float64(loc) / 3600.0
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return basic.StarAzimuth(jde, ra, dec, lon, lat, timezone)
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}
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// Zenith 恒星高度角
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// 返回给定赤经赤纬、经纬度、对应date时区date时刻的太阳高度角
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func Zenith(date time.Time, ra, dec, lon, lat float64) float64 {
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jde := basic.Date2JDE(date)
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_, loc := date.Zone()
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timezone := float64(loc) / 3600.0
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return basic.StarHeight(jde, ra, dec, lon, lat, timezone)
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}
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// CulminationTime 恒星中天时间
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// 返回给定赤经赤纬、经纬度、对应date时区date时刻的太阳中天日期
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func CulminationTime(date time.Time, ra, lon float64) time.Time {
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jde := basic.Date2JDE(date)
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if jde-math.Floor(jde) < 0.5 {
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jde--
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}
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_, loc := date.Zone()
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timezone := float64(loc) / 3600.0
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calcJde := basic.StarCulminationTime(jde, ra, lon, timezone) - timezone/24.00
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return basic.JDE2DateByZone(calcJde, date.Location(), false)
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}
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// InitStarDatabase 初始化恒星数据库
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func InitStarDatabase() error {
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return basic.LoadStarData()
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}
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// 通过恒星HR编号获取恒星参数
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func GetStarDataByHR(hr int) (basic.StarData, error) {
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return basic.StarDataByHR(hr)
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}
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