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213
server/celestial.mjs
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213
server/celestial.mjs
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const RAD = Math.PI / 180
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const DEG = 180 / Math.PI
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function jdn(date) {
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return (date instanceof Date ? date : new Date(date)) / 86400000 + 2440587.5
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}
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function jdnToDate(jd) {
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return new Date((jd - 2440587.5) * 86400000)
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}
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function sunPosition(lat, lon, date = new Date()) {
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const d = jdn(date) - 2451545.0
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const L = (280.46 + 0.9856474 * d) % 360
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const g = (357.528 + 0.9856003 * d) % 360
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const lam = L + 1.915 * Math.sin(g * RAD) + 0.02 * Math.sin(2 * g * RAD)
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const eps = 23.439 - 0.0000004 * d
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const sinL = Math.sin(lam * RAD)
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const ra = Math.atan2(Math.cos(eps * RAD) * sinL, Math.cos(lam * RAD)) * DEG
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const dec = Math.asin(Math.sin(eps * RAD) * sinL) * DEG
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const UT = date.getUTCHours() + date.getUTCMinutes() / 60 + date.getUTCSeconds() / 3600
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const GMST = (6.697375 + 0.0657098242 * d + UT) % 24
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const LMST = (GMST + lon / 15) % 24
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const ha = LMST * 15 - ra
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const elev = Math.asin(
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Math.sin(lat * RAD) * Math.sin(dec * RAD) +
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Math.cos(lat * RAD) * Math.cos(dec * RAD) * Math.cos(ha * RAD)
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) * DEG
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const az = Math.atan2(
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-Math.sin(ha * RAD),
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Math.tan(dec * RAD) * Math.cos(lat * RAD) - Math.sin(lat * RAD) * Math.cos(ha * RAD)
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) * DEG
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return {
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sun_elevation: Math.round(elev * 10) / 10,
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sun_azimuth: Math.round(((az + 360) % 360) * 10) / 10,
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}
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}
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function sunriseSunset(lat, lon, date = new Date()) {
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const d = Math.floor(jdn(date)) - 2451545
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const noon = 2451545 + 0.0009 + ((-lon) / 360) + Math.round(d - (-lon) / 360)
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const M = (357.5291 + 0.98560028 * (noon - 2451545)) % 360
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const C = 1.9148 * Math.sin(M * RAD) + 0.02 * Math.sin(2 * M * RAD) + 0.0003 * Math.sin(3 * M * RAD)
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const lam = (M + C + 180 + 102.9372) % 360
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const jnoon = noon + 0.0053 * Math.sin(M * RAD) - 0.0069 * Math.sin(2 * lam * RAD)
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const dec = Math.asin(Math.sin(23.4397 * RAD) * Math.sin(lam * RAD)) * DEG
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const cosH = (Math.sin(-0.8333 * RAD) - Math.sin(lat * RAD) * Math.sin(dec * RAD)) / (Math.cos(lat * RAD) * Math.cos(dec * RAD))
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if (Math.abs(cosH) > 1) {
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return { sun_sunrise: null, sun_sunset: null, sun_solar_noon: jdnToDate(jnoon).toISOString(), sun_polar: cosH < -1 ? 'day' : 'night' }
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}
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const H = Math.acos(cosH) * DEG
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const rise = jdnToDate(jnoon - H / 360)
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const set = jdnToDate(jnoon + H / 360)
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const noon_d = jdnToDate(jnoon)
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// Round to nearest second, drop milliseconds
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const fmt = d => new Date(Math.round(d.getTime() / 1000) * 1000).toISOString()
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return {
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sun_sunrise: fmt(rise),
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sun_sunset: fmt(set),
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sun_solar_noon: fmt(noon_d),
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sun_day_length_hours: Math.round((set - rise) / 36000) / 100,
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sun_golden_hour_morning_start: fmt(new Date(rise - 30 * 60000)),
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sun_golden_hour_morning_end: fmt(new Date(rise + 30 * 60000)),
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sun_golden_hour_evening_start: fmt(new Date(set - 30 * 60000)),
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sun_golden_hour_evening_end: fmt(new Date(set + 30 * 60000)),
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}
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}
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// Smooth sunspot number approximation from solar flux F10.7
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// SSN ≈ 1.61 * F10.7 - 63.7 (linear regression, valid for F10.7 > 70)
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export function ssnFromFlux(f107) {
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if (!f107) return null
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return Math.max(0, Math.round(1.61 * f107 - 63.7))
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}
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export function sunActivityLabel(f107) {
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if (!f107) return null
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if (f107 < 80) return 'Very Low'
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if (f107 < 100) return 'Low'
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if (f107 < 150) return 'Moderate'
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if (f107 < 200) return 'High'
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return 'Very High'
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}
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function moonPhase(date = new Date()) {
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const jd = jdn(date)
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const cycle = 29.53058867
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const known = 2451550.1
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const phase = ((jd - known) % cycle + cycle) % cycle
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const illum = Math.round((1 - Math.cos(phase / cycle * 2 * Math.PI)) / 2 * 100)
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let name
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if (phase < 1.85) name = 'New Moon'
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else if (phase < 7.38) name = 'Waxing Crescent'
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else if (phase < 9.22) name = 'First Quarter'
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else if (phase < 14.76) name = 'Waxing Gibbous'
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else if (phase < 16.61) name = 'Full Moon'
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else if (phase < 22.15) name = 'Waning Gibbous'
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else if (phase < 23.99) name = 'Last Quarter'
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else name = 'Waning Crescent'
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return { moon_phase: name, moon_illumination_pct: illum }
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}
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function nextMoonEvents(date = new Date()) {
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const cycle = 29.53058867
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const jd = jdn(date)
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const known = 2451550.1
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const phase = ((jd - known) % cycle + cycle) % cycle
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const toNew = (cycle - phase) % cycle
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const toFull = phase < 14.76 ? 14.76 - phase : cycle - phase + 14.76
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return {
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moon_next_new: jdnToDate(jd + toNew).toISOString(),
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moon_next_full: jdnToDate(jd + toFull).toISOString(),
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}
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}
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function moonriseMoonset(lat, lon, date = new Date()) {
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const base = new Date(date)
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base.setUTCHours(0, 0, 0, 0)
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let prev = null
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let moonrise = null
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let moonset = null
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// Scan 48h in 10min steps — covers edge cases where moon rises/sets next UTC day
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for (let m = 0; m <= 2880; m += 10) {
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const t = new Date(base.getTime() + m * 60000)
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const d = jdn(t) - 2451545
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const L = (218.316 + 13.176396 * d) % 360
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const M = (134.963 + 13.064993 * d) % 360
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const F = (93.272 + 13.229350 * d) % 360
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const lon_ = L + 6.289 * Math.sin(M * RAD)
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const b = 5.128 * Math.sin(F * RAD)
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const dec = Math.asin(
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Math.sin(b * RAD) * Math.cos(23.4397 * RAD) +
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Math.cos(b * RAD) * Math.sin(23.4397 * RAD) * Math.sin(lon_ * RAD)
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) * DEG
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const GMST = (6.697375 + 0.0657098242 * d + (t.getUTCHours() + t.getUTCMinutes() / 60)) % 24
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const LMST = (GMST + lon / 15) % 24
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const ra = Math.atan2(
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Math.sin(lon_ * RAD) * Math.cos(23.4397 * RAD) - Math.tan(b * RAD) * Math.sin(23.4397 * RAD),
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Math.cos(lon_ * RAD)
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) * DEG
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const ha = LMST * 15 - ra
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const elev = Math.asin(
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Math.sin(lat * RAD) * Math.sin(dec * RAD) +
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Math.cos(lat * RAD) * Math.cos(dec * RAD) * Math.cos(ha * RAD)
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) * DEG
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if (prev !== null) {
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if (prev < 0 && elev >= 0 && !moonrise) moonrise = new Date(t.getTime() - 5 * 60000).toISOString()
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if (prev >= 0 && elev < 0 && !moonset) moonset = new Date(t.getTime() - 5 * 60000).toISOString()
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}
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prev = elev
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if (moonrise && moonset) break
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}
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return { moon_moonrise: moonrise, moon_moonset: moonset }
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}
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function nextSolsticeEquinox(date = new Date()) {
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const y = date.getFullYear()
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const events = [
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{ name: 'March Equinox', date: new Date(Date.UTC(y, 2, 20)) },
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{ name: 'June Solstice', date: new Date(Date.UTC(y, 5, 21)) },
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{ name: 'September Equinox', date: new Date(Date.UTC(y, 8, 22)) },
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{ name: 'December Solstice', date: new Date(Date.UTC(y, 11, 21)) },
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{ name: 'March Equinox', date: new Date(Date.UTC(y+1, 2, 20)) },
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]
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const next = events.find(e => e.date > date)
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const prev = [...events].reverse().find(e => e.date <= date)
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return {
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season_next_event: next.name,
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season_next_event_date: next.date.toISOString(),
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season_last_event: prev?.name || null,
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season_last_event_date: prev?.date.toISOString() || null,
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}
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}
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export function getCelestialCurrent(lat, lon, date = new Date()) {
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return {
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...sunPosition(lat, lon, date),
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...sunriseSunset(lat, lon, date),
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...moonPhase(date),
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...nextMoonEvents(date),
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...moonriseMoonset(lat, lon, date),
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...nextSolsticeEquinox(date),
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}
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}
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export function getCelestialHourly(lat, lon, hours) {
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return hours.map(({ time }) => {
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const d = new Date(time)
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const pos = sunPosition(lat, lon, d)
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const phase = moonPhase(d)
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return { time, ...pos, moon_illumination_pct: phase.moon_illumination_pct, moon_phase: phase.moon_phase }
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})
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}
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export function getCelestialDaily(lat, lon, days) {
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return days.map(({ time }) => {
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const d = new Date(time)
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return {
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time,
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...sunriseSunset(lat, lon, d),
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...moonPhase(d),
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...nextMoonEvents(d),
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...moonriseMoonset(lat, lon, d),
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}
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})
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}
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