74 lines
2.5 KiB
Go
74 lines
2.5 KiB
Go
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package venus
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import (
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"time"
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"b612.me/astro/basic"
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)
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// TransitInfo 地心金星凌日信息 / geocentric Venus transit information.
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//
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// Start、Greatest、End、InternalStart、InternalEnd 都保持调用者输入的时区。
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// 内切接触不存在时 InternalStart / InternalEnd 为零值。
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// Start, Greatest, End, InternalStart, and InternalEnd preserve the caller's timezone.
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// InternalStart and InternalEnd are zero values when internal contacts do not exist.
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type TransitInfo struct {
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Valid bool
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Start time.Time
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InternalStart time.Time
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Greatest time.Time
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InternalEnd time.Time
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End time.Time
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Duration time.Duration
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InternalDuration time.Duration
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MinimumSeparationArcsec float64
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SunSemidiameterArcsec float64
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PlanetSemidiameterArcsec float64
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HasInternal bool
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}
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// NextTransit 下一次地心金星凌日 / next geocentric Venus transit.
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func NextTransit(date time.Time) TransitInfo {
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return transitInfoFromBasic(basic.NextVenusTransit(basic.Date2JDE(date.UTC())), date.Location())
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}
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// LastTransit 上一次地心金星凌日 / previous geocentric Venus transit.
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func LastTransit(date time.Time) TransitInfo {
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return transitInfoFromBasic(basic.LastVenusTransit(basic.Date2JDE(date.UTC())), date.Location())
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}
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// ClosestTransit 最近一次地心金星凌日 / closest geocentric Venus transit.
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func ClosestTransit(date time.Time) TransitInfo {
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return transitInfoFromBasic(basic.ClosestVenusTransit(basic.Date2JDE(date.UTC())), date.Location())
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}
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func transitInfoFromBasic(result basic.PlanetTransitResult, loc *time.Location) TransitInfo {
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if !result.Valid {
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return TransitInfo{}
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}
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start := basic.JDE2DateByZone(result.ExternalIngress, loc, false)
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greatest := basic.JDE2DateByZone(result.Greatest, loc, false)
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end := basic.JDE2DateByZone(result.ExternalEgress, loc, false)
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info := TransitInfo{
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Valid: true,
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Start: start,
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Greatest: greatest,
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End: end,
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Duration: end.Sub(start),
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MinimumSeparationArcsec: result.MinimumSeparationArcsec,
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SunSemidiameterArcsec: result.SunSemidiameterArcsec,
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PlanetSemidiameterArcsec: result.PlanetSemidiameterArcsec,
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HasInternal: result.HasInternal,
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}
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if result.HasInternal {
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info.InternalStart = basic.JDE2DateByZone(result.InternalIngress, loc, false)
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info.InternalEnd = basic.JDE2DateByZone(result.InternalEgress, loc, false)
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info.InternalDuration = info.InternalEnd.Sub(info.InternalStart)
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}
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return info
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}
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