def phase_hunt(sdate=DateTime.now()):
"""Find time of phases of the moon which surround the current date.
Five phases are found, starting and ending with the new moons
which bound the current lunation.
"""
if not hasattr(sdate, 'jdn'):
sdate = DateTime.DateTimeFromJDN(sdate)
adate = sdate + DateTime.RelativeDateTime(days=-45)
k1 = floor(
(adate.year + ((adate.month - 1) * (1.0 / 12.0)) - 1900) * 12.3685)
nt1 = meanphase(adate, k1)
adate = nt1
sdate = sdate.jdn
while 1:
adate = adate + c.synodic_month
k2 = k1 + 1
nt2 = meanphase(adate, k2)
if nt1 <= sdate < nt2:
break
nt1 = nt2
k1 = k2
phases = list(
map(truephase, [k1, k1, k1, k1, k2],
[0 / 4.0, 1 / 4.0, 2 / 4.0, 3 / 4.0, 0 / 4.0]))
return phases
def __str__(self):
if type(self.date) is int:
d = DateTime.DateTimeFromJDN(self.date)
else:
d = self.date
s = "%s for %s, %s (%%%.2f illuminated)" %\
(self.__class__, d.strftime(), self.phase_text,
self.illuminated * 100)
return s
def __init__(self, date=DateTime.now()):
"""MoonPhase constructor.
Give me a date, as either a Julian Day Number or a DateTime
object."""
if not isinstance(date, DateTime.DateTimeType):
self.date = DateTime.DateTimeFromJDN(date)
else:
self.date = date
self.__dict__.update(phase(self.date))
self.phase_text = phase_string(self.phase)
def truephase(k, tphase):
"""Given a K value used to determine the mean phase of the new
moon, and a phase selector (0.0, 0.25, 0.5, 0.75), obtain the
true, corrected phase time."""
apcor = False
# add phase to new moon time
k = k + tphase
# Time in Julian centuries from 1900 January 0.5
t = k / 1236.85
t2 = t * t
t3 = t2 * t
# Mean time of phase
pt = (2415020.75933 + c.synodic_month * k + 0.0001178 * t2 -
0.000000155 * t3 +
0.00033 * dsin(166.56 + 132.87 * t - 0.009173 * t2))
# Sun's mean anomaly
m = 359.2242 + 29.10535608 * k - 0.0000333 * t2 - 0.00000347 * t3
# Moon's mean anomaly
mprime = 306.0253 + 385.81691806 * k + 0.0107306 * t2 + 0.00001236 * t3
# Moon's argument of latitude
f = 21.2964 + 390.67050646 * k - 0.0016528 * t2 - 0.00000239 * t3
if (tphase < 0.01) or (abs(tphase - 0.5) < 0.01):
# Corrections for New and Full Moon
pt = pt + (
(0.1734 - 0.000393 * t) * dsin(m) + 0.0021 * dsin(2 * m) -
0.4068 * dsin(mprime) + 0.0161 * dsin(2 * mprime) -
0.0004 * dsin(3 * mprime) + 0.0104 * dsin(2 * f) -
0.0051 * dsin(m + mprime) - 0.0074 * dsin(m - mprime) +
0.0004 * dsin(2 * f + m) - 0.0004 * dsin(2 * f - m) -
0.0006 * dsin(2 * f + mprime) + 0.0010 * dsin(2 * f - mprime) +
0.0005 * dsin(m + 2 * mprime))
apcor = True
elif (abs(tphase - 0.25) < 0.01) or (abs(tphase - 0.75) < 0.01):
pt = pt + (
(0.1721 - 0.0004 * t) * dsin(m) + 0.0021 * dsin(2 * m) -
0.6280 * dsin(mprime) + 0.0089 * dsin(2 * mprime) -
0.0004 * dsin(3 * mprime) + 0.0079 * dsin(2 * f) -
0.0119 * dsin(m + mprime) - 0.0047 * dsin(m - mprime) +
0.0003 * dsin(2 * f + m) - 0.0004 * dsin(2 * f - m) -
0.0006 * dsin(2 * f + mprime) + 0.0021 * dsin(2 * f - mprime) +
0.0003 * dsin(m + 2 * mprime) + 0.0004 * dsin(m - 2 * mprime) -
0.0003 * dsin(2 * m + mprime))
if (tphase < 0.5):
# First quarter correction
pt = pt + 0.0028 - 0.0004 * dcos(m) + 0.0003 * dcos(mprime)
else:
# Last quarter correction
pt = pt + -0.0028 + 0.0004 * dcos(m) - 0.0003 * dcos(mprime)
apcor = True
if not apcor:
raise ValueError("TRUEPHASE called with invalid phase selector",
tphase)
return DateTime.DateTimeFromJDN(pt)
