def solar_north(t=None):
"""Returns the position of the Solar north pole in degrees."""
jd = util.julian_day(t)
T = util.julian_centuries(t)
ob1 = true_obliquity_of_ecliptic(t)
theta = (jd - 2398220)*360/25.38
# in degrees
i = 7.25
k = 74.3646 + 1.395833 * T
lamda = true_longitude(t) - 0.00569
omega = apparent_longitude(t)
lamda2 = lamda - 0.00479 * math.sin(np.radians(omega))
diff = np.radians(lamda - k)
x = np.degrees(math.atan(-math.cos(np.radians(lamda2)*math.tan(np.radians(ob1)))))
y = np.degrees(math.atan(-math.cos(diff)*math.tan(np.radians(i))))
result = x + y
return result
def heliographic_solar_center(t=None):
"""Returns the position of the solar center in heliographic coordinates."""
jd = util.julian_day(t)
T = util.julian_centuries(t)
# Heliographic coordinates in degrees
theta = (jd - 2398220) * 360 / 25.38
i = 7.25
k = 74.3646 + 1.395833 * T
lamda = true_longitude(t) - 0.00569
omega = apparent_longitude(t)
lamda2 = lamda - 0.00479 * math.sin(np.radians(omega))
diff = np.radians(lamda - k)
# Latitude at center of disk (deg):
he_lat = np.degrees(math.asin(math.sin(diff) * math.sin(np.radians(i))))
# Longitude at center of disk (deg):
y = -math.sin(diff) * math.cos(np.radians(i))
x = -math.cos(diff)
rpol = cmath.polar(complex(x, y))
he_lon = np.degrees(rpol[1]) - theta
he_lon = he_lon % 360
if he_lon < 0:
he_lon = he_lon + 360.0
return [he_lon, he_lat]
def test_julian_day():
assert util.julian_day('1900-01-01 12:00') == 2415021.0
assert util.julian_day(LANDING) == 2439159.5
result = util.julian_day('2000-03-01 15:30:26')
assert_almost_equal(result, 2451605.1461111, decimal=3)
def carrington_rotation_number(t=None):
"""Return the Carrington Rotation number"""
jd = util.julian_day(t)
result = (1.0 / 27.2753) * (jd - 2398167.0) + 1.0
return result
