def location(cls, tee):
"""Return location of Beijing; time zone varies with time, tee."""
year = GregorianDate.to_year(ifloor(tee))
if (year < 1929):
return Location(angle(39, 55, 0), angle(116, 25, 0), 43.5, Clock.days_from_hours(1397/180))
else:
return Location(angle(39, 55, 0), angle(116, 25, 0), 43.5, Clock.days_from_hours(8))
def vietnamese_location(tee):
"""Return the location for Vietnamese calendar is Hanoi;
varies with moment, tee. Time zone has changed over the years."""
if (tee < GregorianDate.new_year(1968)):
z = 8
else:
z =7
return Location(angle(21, 2, 0), angle(105, 51, 0), 12, Clock.days_from_hours(z))
def obliquity(cls, tee):
"""Return (mean) obliquity of ecliptic at moment tee."""
c = cls.julian_centuries(tee)
return (angle(23, 26, mpf(21.448)) +
poly(c, [mpf(0),
angle(0, 0, mpf(-46.8150)),
angle(0, 0, mpf(-0.00059)),
angle(0, 0, mpf(0.001813))]))
def korean_location(tee):
"""Return the location for Korean calendar; varies with moment, tee."""
# Seoul city hall at a varying time zone.
if (tee < GregorianDate(1908, MonthOfYear.April, 1).to_fixed()):
#local mean time for longitude 126 deg 58 min
z = 3809/450
elif (tee < GregorianDate(1912, MonthOfYear.January, 1).to_fixed()):
z = 8.5
elif (tee < GregorianDate(1954, MonthOfYear.March, 21).to_fixed()):
z = 9
elif (tee < GregorianDate(1961, MonthOfYear.August, 10).to_fixed()):
z = 8.5
else:
z = 9
return Location(angle(37, 34, 0), angle(126, 58, 0), 0, Clock.days_from_hours(z))
def arcsin(cls, amp):
"""Return the inverse of Hindu sine function of amp."""
if (amp < 0):
return -cls.arcsin(-amp)
else:
pos = next_int(0, lambda k: amp <= cls.sine_table(k))
below = cls.sine_table(pos - 1)
return (angle(0, 225, 0) * (pos - 1 + ((amp - below) / (cls.sine_table(pos) - below))))
def daily_motion(cls, date):
"""Return the sidereal daily motion of sun on date, date."""
mean_motion = 360 / cls.SIDEREAL_YEAR
anomaly = cls.mean_position(date, cls.ANOMALISTIC_YEAR)
epicycle = 14/360 - abs(cls.sine(anomaly)) / 1080
entry = quotient(float(anomaly), angle(0, 225, 0))
sine_table_step = cls.sine_table(entry + 1) - cls.sine_table(entry)
factor = -3438/225 * sine_table_step * epicycle
return mean_motion * (factor + 1)
def japanese_location(tee):
"""Return the location for Japanese calendar; varies with moment, tee."""
year = GregorianDate.to_year(ifloor(tee))
if (year < 1888):
# Tokyo (139 deg 46 min east) local time
loc = Location(mpf(35.7), angle(139, 46, 0), 24, Clock.days_from_hours(9 + 143/450))
else:
# Longitude 135 time zone
loc = Location(35, 135, 0, Clock.days_from_hours(9))
return loc
def refraction(self, tee):
"""Return refraction angle at location 'location' and time 'tee'."""
h = max(0, self.elevation)
cap_R = 6.372E6
dip = arccos_degrees(cap_R / (cap_R + h))
return angle(0, 50, 0) + dip + secs(19) * math.sqrt(h)
ignoring parallax and refraction. Adapted from 'Astronomical
Algorithms' by Jean Meeus, Willmann_Bell, Inc., 1998."""
lamb = Lunar.lunar_longitude(tee)
beta = Lunar.lunar_latitude(tee)
alpha = Astro.right_ascension(tee, beta, lamb)
delta = Astro.declination(tee, beta, lamb)
theta0 = Astro.sidereal_from_moment(tee)
cap_H = mod(theta0 + self.longitude - alpha, 360)
altitude = arcsin_degrees(
(sin_degrees(self.latitude) * sin_degrees(delta)) +
(cos_degrees(self.latitude) * cos_degrees(delta) * cos_degrees(cap_H)))
return mod(altitude + 180, 360) - 180
def visible_crescent(self, date):
"""Return S. K. Shaukat's criterion for likely
visibility of crescent moon on eve of date 'date',
at location 'location'."""
tee = self.universal_from_standard(self.dusk(date - 1, mpf(4.5)))
phase = Lunar.lunar_phase(tee)
altitude = self.lunar_altitude(tee)
arc_of_light = arccos_degrees(cos_degrees(Lunar.lunar_latitude(tee)) * cos_degrees(phase))
return ((Lunar.NEW < phase < Lunar.FIRST_QUARTER) and
(mpf(10.6) <= arc_of_light <= 90) and
(altitude > mpf(4.1)))
MECCA = Location(angle(21, 25, 24), angle(39, 49, 24), 298, Clock.days_from_hours(3))
JERUSALEM = Location(31.8, 35.2, 800, Clock.days_from_hours(2))
BRUXELLES = Location(angle(4, 21, 17), angle(50, 50, 47), 800, Clock.days_from_hours(1))
URBANA = Location(40.1, -88.2, 225, Clock.days_from_hours(-6))
GREENWHICH = Location(51.4777815, 0, 46.9, Clock.days_from_hours(0))
def yoga(date):
"""Return the Hindu yoga on date, date."""
return ifloor(mod((HinduSolarDate.longitude(date) + HinduLunarDate.longitude(date)) / angle(0, 800, 0), 27)) + 1
def hindu_lunar_station(date):
"""Return the Hindu lunar station (nakshatra) at sunrise on date, date."""
critical = HinduDate.sunrise(date)
return quotient(HinduLunarDate.longitude(critical), angle(0, 800, 0)) + 1
def alt_sunrise(cls, date):
"""Return the astronomical sunrise at Hindu location on date, date,
per Lahiri, rounded to nearest minute, as a rational number."""
rise = cls.UJJAIN.dawn(date, angle(0, 47, 0))
return 1/24 * 1/60 * iround(rise * 24 * 60)
def sine(cls, theta):
"""Return the linear interpolation for angle, theta, in Hindu table."""
entry = theta / angle(0, 225, 0)
fraction = mod(entry, 1)
return ((fraction * cls.sine_table(iceiling(entry))) + ((1 - fraction) * cls.sine_table(ifloor(entry))))
def sine_table(cls, entry):
"""Return the value for entry in the Hindu sine table.
Entry, entry, is an angle given as a multiplier of 225'."""
exact = 3438 * sin_degrees(entry * angle(0, 225, 0))
error = 0.215 * signum(exact) * signum(abs(exact) - 1716)
return iround(exact + error) / 3438
def equation_of_time(cls, date):
"""Return the time from true to mean midnight of date, date."""
offset = cls.sine(cls.mean_position(date, cls.ANOMALISTIC_YEAR))
equation_sun = (offset * angle(57, 18, 0) * (14/360 - (abs(offset) / 1080)))
return ((cls.daily_motion(date) / 360) * (equation_sun / 360) * cls.SIDEREAL_YEAR)
def precise_obliquity(cls, tee):
"""Return precise (mean) obliquity of ecliptic at moment tee."""
u = cls.julian_centuries(tee) / 100
#assert(abs(u) < 1,
# 'Error! This formula is valid for +/-10000 years around J2000.0')
return (poly(u, [angle(23, 26, mpf(21.448)),
angle(0, 0, mpf(-4680.93)),
angle(0, 0, mpf(- 1.55)),
angle(0, 0, mpf(+1999.25)),
angle(0, 0, mpf(- 51.38)),
angle(0, 0, mpf(- 249.67)),
angle(0, 0, mpf(- 39.05)),
angle(0, 0, mpf(+ 7.12)),
angle(0, 0, mpf(+ 27.87)),
angle(0, 0, mpf(+ 5.79)),
angle(0, 0, mpf(+ 2.45))]))
elif month == HebrewMonth.KISLEV and day < 30:
extra = [DayOfWeek.Monday, DayOfWeek.Wednesday, DayOfWeek.Friday]
elif month == HebrewMonth.KISLEV and day == 30:
extra = [DayOfWeek.Monday]
elif month in [HebrewMonth.TEVET, HebrewMonth.SHEVAT]:
extra = [DayOfWeek.Sunday, DayOfWeek.Monday]
elif month == HebrewMonth.ADAR and day < 30:
extra = [DayOfWeek.Sunday, DayOfWeek.Monday]
else:
extra = [DayOfWeek.Sunday]
basic.extend(extra)
return map(lambda x: DayOfWeek.from_fixed(x + n), basic)
JAFFA = Location(angle(32, 1, 60), angle(34, 45, 0), 0, Clock.days_from_hours(2))
class HebrewObservationalDate(YearMonthDay):
def __init__(self, year, month, day):
YearMonthDay.__init__(self, year, month, day)
def to_fixed(self):
"""Return fixed date equivalent to Observational Hebrew date."""
year1 = self.year - 1 if self.month >= HebrewMonth.TISHRI else self.year
start = HebrewDate(year1, HebrewMonth.NISAN, 1).to_fixed()
g_year = GregorianDate.to_year(start + 60)
new_year = self.new_year(g_year)
midmonth = new_year + iround(29.5 * (self.month - 1)) + 15
return JAFFA.phasis_on_or_before(midmonth) + self.day - 1
