def _from_string_time (cls, s, ** kw) :
future = kw.get ("future")
date = kw.get ("date") or CAL.Date ()
now = kw.get ("time") or CAL.Time ()
time = CAL.Time.from_string (s)
if future and time < now :
date += 1
return cls.combine (date, time)
def _to_local_time(self, hours_ut):
dt = CAL.Date_Time.combine(self.day, self.time_ut)
delta = self.loc.tz.utcoffset(dt._body)
return CAL.Time(time=(dt + delta)._body.time())
class Time (TFL.Meta.Object) :
"""Model astronomical time for a single Date.
### Example 12.a of J. Meeus, p. 88
>>> date = CAL.Date (1987, 4, 10)
>>> xa = Time (date)
>>> print (portable_repr (xa.t))
-0.127296372348
>>> print (xa.mean_sidereal_time)
13:10:46.366826
>>> print (xa.sidereal_time)
13:10:46.357311
### Example 12.b of J. Meeus, p. 89
>>> dt = CAL.Date_Time (1987, 4, 10, 19, 21, 0)
>>> xb = Time (dt)
>>> print (portable_repr (xb.t))
-0.127274298426
>>> print (xb.mean_sidereal_time)
08:34:57.089579
"""
time = CAL.Time (0)
def __init__ (self, date) :
"""`date` must be in UT."""
if isinstance (date, CAL.Date_Time) :
self.time = date.as_time ()
self.date = date
self.JC_2k = self.t = t = date.JC_J2000
self.JC_2k_squared = self.t2 = t2 = t * t
self.JC_2k_cubed = self.t3 = t * t2
# end def __init__
@Once_Property
def eccentriticy_earth_orbit (self) :
"""Eccentricity of earth's orbit (unitless)."""
### Eq. (25.4)
return 0.016708634 - self.t * 0.000042037 - self.t2 * 0.0000001267
# end def eccentriticy_earth_orbit
@Once_Property
def geometric_mean_anomaly_sun (self) :
"""Geometric mean anomaly of the sun (in degrees)."""
### Eq. (25.3)
return Angle_D.normalized \
(357.52911 + self.t * 35999.05029 - self.t2 * 0.0001537)
# end def geometric_mean_anomaly_sun
@Once_Property
def geometric_mean_longitude_moon (self) :
"""Geometric mean longitude of the moon (in degrees)."""
### see J. Meeus, p. 144;
return Angle_D.normalized \
(218.3165 + self.t * 481267.8813)
# end def geometric_mean_longitude_moon
@Once_Property
def geometric_mean_longitude_sun (self) :
"""Geometric mean longitude of the sun (in degrees)."""
### see J. Meeus, p. 144; Eq. (25.2)
return Angle_D.normalized \
( 280.46646
+ self.t * 36000.76983
+ self.t2 * 0.0003032
)
# end def geometric_mean_longitude_sun
@Once_Property
def longitude_ascending_node_moon (self) :
"""Longitude of the (mean) ascending node of the moon's orbit on the
ecliptic.
"""
### see J. Meeus, p. 144; p.343, Eq. (47.7)
return Angle_D \
( 125.04452
- self.t * 1934.136261
+ self.t2 * 0.0020708
+ self.t3 / 450000.0
)
# end def longitude_ascending_node_moon
@Once_Property
def mean_obliquity_ecliptic (self) :
"""Mean obliquity of the ecliptic (in degrees)."""
### see J. Meeus, p. 147, Eq. (22.2)
return \
( Angle_D (23, 26, 21.448)
- Angle_D (seconds = 46.815000) * self.t
- Angle_D (seconds = 0.000590) * self.t2
+ Angle_D (seconds = 0.001813) * self.t3
)
# end def mean_obliquity_ecliptic
@Once_Property
def mean_sidereal_deg (self) :
"""Mean sidereal time at `self.date` and `self.time` in degrees."""
seconds = self.time.seconds
if seconds == 0 :
### J. Meeus, eq. (12.3), p. 87
result = 100.46061837 + 36000.770053608 * self.t
else :
### J. Meeus, eq. (12.4), p. 88
result = \
( 280.46061837
+ 360.98564736629 * (self.date.JD - 2451545.0)
)
### J. Meeus, eq. (12.3 + 12.4), p. 87
result += 0.000387933 * self.t2 - self.t3 / 38710000.0
return result % 360.0
# end def mean_sidereal_deg
@Once_Property
def mean_sidereal_time (self) :
"""Mean sidereal time at `self.date` and `self.time`."""
return CAL.Time.from_degrees (self.mean_sidereal_deg)
# end def mean_sidereal_time
@Once_Property
def nutation_longitude (self) :
"""Nutation in longitude (delta-phi)."""
### see J. Meeus, pp. 143–4
omega = self.longitude_ascending_node_moon
om_2 = omega * 2
ls_2 = self.geometric_mean_longitude_sun * 2
lm_2 = self.geometric_mean_longitude_moon * 2
result = \
( Angle_D (seconds = -17.20) * omega.sin
- Angle_D (seconds = - 1.32) * ls_2.sin
- Angle_D (seconds = 0.23) * lm_2.sin
+ Angle_D (seconds = 0.21) * om_2.sin
)
return result
# end def nutation_longitude
@Once_Property
def nutation_obliquity (self) :
"""Nutation in obliquity (delta-epsilon)."""
### see J. Meeus, pp. 143–4
omega = self.longitude_ascending_node_moon
om_2 = omega * 2
ls_2 = self.geometric_mean_longitude_sun * 2
lm_2 = self.geometric_mean_longitude_moon * 2
result = \
( Angle_D (seconds = 9.20) * omega.cos
+ Angle_D (seconds = 0.57) * ls_2.cos
+ Angle_D (seconds = 0.10) * lm_2.cos
- Angle_D (seconds = 0.09) * om_2.cos
)
return result
# end def nutation_obliquity
@Once_Property
def obliquity_corrected (self) :
"""Corrected obliquity of the ecliptic (in degrees)."""
### Eq. (25.8)
return \
( self.mean_obliquity_ecliptic
+ 0.00256 * self.longitude_ascending_node_moon.cos
)
# end def obliquity_corrected
@Once_Property
def sidereal_deg (self) :
"""Apparent sidereal time at `self.date` and `self.time` in degrees."""
### see J. Meeus, p. 95
result = \
( Angle_D.normalized (self.mean_sidereal_deg)
+ (self.nutation_longitude / 15) * self.obliquity_corrected.cos
)
return result
# end def sidereal_deg
@Once_Property
def sidereal_time (self) :
"""Apparent sidereal time at `self.date` and `self.time`."""
return CAL.Time.from_degrees (self.sidereal_deg)
def as_time (self) :
"""Return `self` converted to pure `Time`."""
return CAL.Time (time = self._body.time ())
