44 lines
1.6 KiB
Go
44 lines
1.6 KiB
Go
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package saturn
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import (
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"time"
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"b612.me/astro/basic"
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"b612.me/astro/calendar"
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)
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// RingInfo 土星环观测参数 / Saturn ring observing parameters.
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type RingInfo struct {
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// EarthLatitude 地球在土星环面上的土星心纬度 B，单位度 / Saturnicentric latitude of Earth, degrees.
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EarthLatitude float64
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// SunLatitude 太阳在土星环面上的土星心纬度 B'，单位度 / Saturnicentric latitude of Sun, degrees.
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SunLatitude float64
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// PositionAngle 土星环北半短轴位置角，单位度 / position angle of the northern semiminor axis, degrees.
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PositionAngle float64
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// DeltaU 太阳和地球在环面内的土星心黄经差，单位度 / difference of Saturnicentric ring longitudes, degrees.
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DeltaU float64
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// MajorAxis 土星环外缘长轴，单位角秒 / outer ring major axis, arcseconds.
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MajorAxis float64
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// MinorAxis 土星环外缘短轴，单位角秒 / outer ring minor axis, arcseconds.
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MinorAxis float64
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}
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// Ring 土星环观测参数 / Saturn ring observing parameters.
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func Ring(date time.Time) RingInfo {
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return RingN(date, -1)
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}
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// RingN 土星环观测参数（截断版） / truncated Saturn ring observing parameters.
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func RingN(date time.Time, n int) RingInfo {
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jde := calendar.Date2JDE(date.UTC())
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earthLatitude, sunLatitude, positionAngle, deltaU, majorAxis, minorAxis := basic.SaturnRingParametersN(basic.TD2UT(jde, true), n)
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return RingInfo{
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EarthLatitude: earthLatitude,
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SunLatitude: sunLatitude,
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PositionAngle: positionAngle,
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DeltaU: deltaU,
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MajorAxis: majorAxis,
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MinorAxis: minorAxis,
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}
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}
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