# The MIT License (MIT)
#
# Copyright (c) 2016 Samuel Bear Powell
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
import numpy as np
from datetime import datetime
class _sp:
@staticmethod
def calendar_time(dt):
try:
x = dt.year, dt.month, dt.day, dt.hour, dt.minute, dt.second, dt.microsecond
return x
except AttributeError:
try:
return _sp.calendar_time(datetime.utcfromtimestamp(dt)) #will raise OSError if dt is not acceptable
except:
raise TypeError('dt must be datetime object or POSIX timestamp')
@staticmethod
def julian_day(dt):
"""Calculate the Julian Day from a datetime.datetime object in UTC"""
# year and month numbers
yr, mo, dy, hr, mn, sc, us = _sp.calendar_time(dt)
if mo <= 2: # From paper: "if M = 1 or 2, then Y = Y - 1 and M = M + 12"
mo += 12
yr -= 1
# day of the month with decimal time
dy = dy + hr/24.0 + mn/(24.0*60.0) + sc/(24.0*60.0*60.0) + us/(24.0*60.0*60.0*1e6)
# b is equal to 0 for the julian calendar and is equal to (2- A +
# INT(A/4)), A = INT(Y/100), for the gregorian calendar
a = int(yr / 100)
b = 2 - a + int(a / 4)
jd = int(365.25 * (yr + 4716)) + int(30.6001 * (mo + 1)) + dy + b - 1524.5
return jd
@staticmethod
def julian_ephemeris_day(jd, deltat):
"""Calculate the Julian Ephemeris Day from the Julian Day and delta-time = (terrestrial time - universal time) in seconds"""
return jd + deltat / 86400.0
@staticmethod
def julian_century(jd):
"""Caluclate the Julian Century from Julian Day or Julian Ephemeris Day"""
return (jd - 2451545.0) / 36525.0
@staticmethod
def julian_millennium(jc):
"""Calculate the Julian Millennium from Julian Ephemeris Century"""
return jc / 10.0
# Earth Periodic Terms
# Earth Heliocentric Longitude coefficients (L0, L1, L2, L3, L4, and L5 in paper)
_EHL_ = [#L0:
[(175347046, 0.0, 0.0), (3341656, 4.6692568, 6283.07585), (34894, 4.6261, 12566.1517),
(3497, 2.7441, 5753.3849), (3418, 2.8289, 3.5231), (3136, 3.6277, 77713.7715),
(2676, 4.4181, 7860.4194), (2343, 6.1352, 3930.2097), (1324, 0.7425, 11506.7698),
(1273, 2.0371, 529.691), (1199, 1.1096, 1577.3435), (990, 5.233, 5884.927),
(902, 2.045, 26.298), (857, 3.508, 398.149), (780, 1.179, 5223.694),
(753, 2.533, 5507.553), (505, 4.583, 18849.228), (492, 4.205, 775.523),
(357, 2.92, 0.067), (317, 5.849, 11790.629), (284, 1.899, 796.298),
(271, 0.315, 10977.079), (243, 0.345, 5486.778), (206, 4.806, 2544.314),
(205, 1.869, 5573.143), (202, 2.4458, 6069.777), (156, 0.833, 213.299),
(132, 3.411, 2942.463), (126, 1.083, 20.775), (115, 0.645, 0.98),
(103, 0.636, 4694.003), (102, 0.976, 15720.839), (102, 4.267, 7.114),
(99, 6.21, 2146.17), (98, 0.68, 155.42), (86, 5.98, 161000.69),
(85, 1.3, 6275.96), (85, 3.67, 71430.7), (80, 1.81, 17260.15),
(79, 3.04, 12036.46), (71, 1.76, 5088.63), (74, 3.5, 3154.69),
(74, 4.68, 801.82), (70, 0.83, 9437.76), (62, 3.98, 8827.39),
(61, 1.82, 7084.9), (57, 2.78, 6286.6), (56, 4.39, 14143.5),
(56, 3.47, 6279.55), (52, 0.19, 12139.55), (52, 1.33, 1748.02),
(51, 0.28, 5856.48), (49, 0.49, 1194.45), (41, 5.37, 8429.24),
(41, 2.4, 19651.05), (39, 6.17, 10447.39), (37, 6.04, 10213.29),
(37, 2.57, 1059.38), (36, 1.71, 2352.87), (36, 1.78, 6812.77),
(33, 0.59, 17789.85), (30, 0.44, 83996.85), (30, 2.74, 1349.87),
(25, 3.16, 4690.48)],
#L1:
[(628331966747, 0.0, 0.0), (206059, 2.678235, 6283.07585), (4303, 2.6351, 12566.1517),
(425, 1.59, 3.523), (119, 5.796, 26.298), (109, 2.966, 1577.344),
(93, 2.59, 18849.23), (72, 1.14, 529.69), (68, 1.87, 398.15),
(67, 4.41, 5507.55), (59, 2.89, 5223.69), (56, 2.17, 155.42),
(45, 0.4, 796.3), (36, 0.47, 775.52), (29, 2.65, 7.11),
(21, 5.34, 0.98), (19, 1.85, 5486.78), (19, 4.97, 213.3),
(17, 2.99, 6275.96), (16, 0.03, 2544.31), (16, 1.43, 2146.17),
(15, 1.21, 10977.08), (12, 2.83, 1748.02), (12, 3.26, 5088.63),
(12, 5.27, 1194.45), (12, 2.08, 4694), (11, 0.77, 553.57),
(10, 1.3, 3286.6), (10, 4.24, 1349.87), (9, 2.7, 242.73),
(9, 5.64, 951.72), (8, 5.3, 2352.87), (6, 2.65, 9437.76),
(6, 4.67, 4690.48)],
#L2:
[(52919, 0.0, 0.0), (8720, 1.0721, 6283.0758), (309, 0.867, 12566.152),
(27, 0.05, 3.52), (16, 5.19, 26.3), (16, 3.68, 155.42),
(10, 0.76, 18849.23), (9, 2.06, 77713.77), (7, 0.83, 775.52),
(5, 4.66, 1577.34), (4, 1.03, 7.11), (4, 3.44, 5573.14),
(3, 5.14, 796.3), (3, 6.05, 5507.55), (3, 1.19, 242.73),
(3, 6.12, 529.69), (3, 0.31, 398.15), (3, 2.28, 553.57),
(2, 4.38, 5223.69), (2, 3.75, 0.98)],
#L3:
[(289, 5.844, 6283.076), (35, 0.0, 0.0,), (17, 5.49, 12566.15),
(3, 5.2, 155.42), (1, 4.72, 3.52), (1, 5.3, 18849.23),
(1, 5.97, 242.73)],
#L4:
[(114, 3.142, 0.0), (8, 4.13, 6283.08), (1, 3.84, 12566.15)],
#L5:
[(1, 3.14, 0.0)]
]
#Earth Heliocentric Longitude coefficients (B0 and B1 in paper)
_EHB_ = [ #B0:
[(280, 3.199, 84334.662), (102, 5.422, 5507.553), (80, 3.88, 5223.69),
(44, 3.7, 2352.87), (32, 4.0, 1577.34)],
#B1:
[(9, 3.9, 5507.55), (6, 1.73, 5223.69)]
]
#Earth Heliocentric Radius coefficients (R0, R1, R2, R3, R4)
_EHR_ = [#R0:
[(100013989, 0.0, 0.0), (1670700, 3.0984635, 6283.07585), (13956, 3.05525, 12566.1517),
(3084, 5.1985, 77713.7715), (1628, 1.1739, 5753.3849), (1576, 2.8469, 7860.4194),
(925, 5.453, 11506.77), (542, 4.564, 3930.21), (472, 3.661, 5884.927),
(346, 0.964, 5507.553), (329, 5.9, 5223.694), (307, 0.299, 5573.143),
(243, 4.273, 11790.629), (212, 5.847, 1577.344), (186, 5.022, 10977.079),
(175, 3.012, 18849.228), (110, 5.055, 5486.778), (98, 0.89, 6069.78),
(86, 5.69, 15720.84), (86, 1.27, 161000.69), (85, 0.27, 17260.15),
(63, 0.92, 529.69), (57, 2.01, 83996.85), (56, 5.24, 71430.7),
(49, 3.25, 2544.31), (47, 2.58, 775.52), (45, 5.54, 9437.76),
(43, 6.01, 6275.96), (39, 5.36, 4694), (38, 2.39, 8827.39),
(37, 0.83, 19651.05), (37, 4.9, 12139.55), (36, 1.67, 12036.46),
(35, 1.84, 2942.46), (33, 0.24, 7084.9), (32, 0.18, 5088.63),
(32, 1.78, 398.15), (28, 1.21, 6286.6), (28, 1.9, 6279.55),
(26, 4.59, 10447.39)],
#R1:
[(103019, 1.10749, 6283.07585), (1721, 1.0644, 12566.1517), (702, 3.142, 0.0),
(32, 1.02, 18849.23), (31, 2.84, 5507.55), (25, 1.32, 5223.69),
(18, 1.42, 1577.34), (10, 5.91, 10977.08), (9, 1.42, 6275.96),
(9, 0.27, 5486.78)],
#R2:
[(4359, 5.7846, 6283.0758), (124, 5.579, 12566.152), (12, 3.14, 0.0),
(9, 3.63, 77713.77), (6, 1.87, 5573.14), (3, 5.47, 18849)],
#R3:
[(145, 4.273, 6283.076), (7, 3.92, 12566.15)],
#R4:
[(4, 2.56, 6283.08)]
]
@staticmethod
def heliocentric_longitude(jme):
"""Compute the Earth Heliocentric Longitude (L) in degrees given the Julian Ephemeris Millennium"""
#L5, ..., L0
Li = [sum(a*np.cos(b + c*jme) for a,b,c in abcs) for abcs in reversed(_sp._EHL_)]
L = np.polyval(Li, jme) / 1e8
L = np.rad2deg(L) % 360
return L
@staticmethod
def heliocentric_latitude(jme):
"""Compute the Earth Heliocentric Latitude (B) in degrees given the Julian Ephemeris Millennium"""
Bi = [sum(a*np.cos(b + c*jme) for a,b,c in abcs) for abcs in reversed(_sp._EHB_)]
B = np.polyval(Bi, jme) / 1e8
B = np.rad2deg(B) % 360
return B
@staticmethod
def heliocentric_radius(jme):
"""Compute the Earth Heliocentric Radius (R) in astronimical units given the Julian Ephemeris Millennium"""
Ri = [sum(a*np.cos(b + c*jme) for a,b,c in abcs) for abcs in reversed(_sp._EHR_)]
R = np.polyval(Ri, jme) / 1e8
return R
@staticmethod
def heliocentric_position(jme):
"""Compute the Earth Heliocentric Longitude, Latitude, and Radius given the Julian Ephemeris Millennium
Returns (L, B, R) where L = longitude in degrees, B = latitude in degrees, and R = radius in astronimical units
"""
return _sp.heliocentric_longitude(jme), _sp.heliocentric_latitude(jme), _sp.heliocentric_radius(jme)
@staticmethod
def geocentric_position(helio_pos):
"""Compute the geocentric latitude (Theta) and longitude (beta) (in degrees) of the sun given the earth's heliocentric position (L, B, R)"""
L,B,R = helio_pos
th = L + 180
b = -B
return (th, b)
#Nutation Longitude and Obliquity coefficients (Y)
_NLOY_ = [(0, 0, 0, 0, 1), (-2, 0, 0, 2, 2), (0, 0, 0, 2, 2),
(0, 0, 0, 0, 2), (0, 1, 0, 0, 0), (0, 0, 1, 0, 0),
(-2, 1, 0, 2, 2), (0, 0, 0, 2, 1), (0, 0, 1, 2, 2),
(-2, -1, 0, 2, 2), (-2, 0, 1, 0, 0), (-2, 0, 0, 2, 1),
(0, 0, -1, 2, 2), (2, 0, 0, 0, 0), (0, 0, 1, 0, 1),
(2, 0, -1, 2, 2), (0, 0, -1, 0, 1), (0, 0, 1, 2, 1),
(-2, 0, 2, 0, 0), (0, 0, -2, 2, 1), (2, 0, 0, 2, 2),
(0, 0, 2, 2, 2), (0, 0, 2, 0, 0), (-2, 0, 1, 2, 2),
(0, 0, 0, 2, 0), (-2, 0, 0, 2, 0), (0, 0, -1, 2, 1),
(0, 2, 0, 0, 0), (2, 0, -1, 0, 1), (-2, 2, 0, 2, 2),
(0, 1, 0, 0, 1), (-2, 0, 1, 0, 1), (0, -1, 0, 0, 1),
(0, 0, 2, -2, 0), (2, 0, -1, 2, 1), (2, 0, 1, 2, 2),
(0, 1, 0, 2, 2), (-2, 1, 1, 0, 0), (0, -1, 0, 2, 2),
(2, 0, 0, 2, 1), (2, 0, 1, 0, 0), (-2, 0, 2, 2, 2),
(-2, 0, 1, 2, 1), (2, 0, -2, 0, 1), (2, 0, 0, 0, 1),
(0, -1, 1, 0, 0), (-2, -1, 0, 2, 1), (-2, 0, 0, 0, 1),
(0, 0, 2, 2, 1), (-2, 0, 2, 0, 1), (-2, 1, 0, 2, 1),
(0, 0, 1, -2, 0), (-1, 0, 1, 0, 0), (-2, 1, 0, 0, 0),
(1, 0, 0, 0, 0), (0, 0, 1, 2, 0), (0, 0, -2, 2, 2),
(-1, -1, 1, 0, 0), (0, 1, 1, 0, 0), (0, -1, 1, 2, 2),
(2, -1, -1, 2, 2), (0, 0, 3, 2, 2), (2, -1, 0, 2, 2)]
#Nutation Longitude and Obliquity coefficients (a,b)
_NLOab_ = [(-171996, -174.2), (-13187, -1.6), (-2274, -0.2), (2062, 0.2), (1426, -3.4), (712, 0.1),
(-517, 1.2), (-386, -0.4), (-301, 0), (217, -0.5), (-158, 0), (129, 0.1),
(123, 0), (63, 0), (63, 0.1), (-59, 0), (-58, -0.1), (-51, 0),
(48, 0), (46, 0), (-38, 0), (-31, 0), (29, 0), (29, 0),
(26, 0), (-22, 0), (21, 0), (17, -0.1), (16, 0), (-16, 0.1),
(-15, 0), (-13, 0), (-12, 0), (11, 0), (-10, 0), (-8, 0),
(7, 0), (-7, 0), (-7, 0), (-7, 0), (6, 0), (6, 0),
(6, 0), (-6, 0), (-6, 0), (5, 0), (-5, 0), (-5, 0),
(-5, 0), (4, 0), (4, 0), (4, 0), (-4, 0), (-4, 0),
(-4, 0), (3, 0), (-3, 0), (-3, 0), (-3, 0), (-3, 0),
(-3, 0), (-3, 0), (-3, 0)]
#Nutation Longitude and Obliquity coefficients (c,d)
_NLOcd_ = [(92025, 8.9), (5736, -3.1), (977, -0.5), (-895, 0.5),
(54, -0.1), (-7, 0), (224, -0.6), (200, 0),
(129, -0.1), (-95, 0.3), (0, 0), (-70, 0),
(-53, 0), (0, 0), (-33, 0), (26, 0),
(32, 0), (27, 0), (0, 0), (-24, 0),
(16, 0), (13, 0), (0, 0), (-12, 0),
(0, 0), (0, 0), (-10, 0), (0, 0),
(-8, 0), (7, 0), (9, 0), (7, 0),
(6, 0), (0, 0), (5, 0), (3, 0),
(-3, 0), (0, 0), (3, 0), (3, 0),
(0, 0), (-3, 0), (-3, 0), (3, 0),
(3, 0), (0, 0), (3, 0), (3, 0),
(3, 0)]
@staticmethod
def ecliptic_obliquity(jme, delta_epsilon):
"""Calculate the true obliquity of the ecliptic (epsilon, in degrees) given the Julian Ephemeris Millennium and the obliquity"""
u = jme/10
e0 = np.polyval([2.45, 5.79, 27.87, 7.12, -39.05, -249.67, -51.38, 1999.25, -1.55, -4680.93, 84381.448], u)
e = e0/3600.0 + delta_epsilon
return e
@staticmethod
def nutation_obliquity(jce):
"""compute the nutation in longitude (delta_psi) and the true obliquity (epsilon) given the Julian Ephemeris Century"""
#mean elongation of the moon from the sun, in radians:
#x0 = 297.85036 + 445267.111480*jce - 0.0019142*(jce**2) + (jce**3)/189474
x0 = np.deg2rad(np.polyval([1./189474, -0.0019142, 445267.111480, 297.85036],jce))
#mean anomaly of the sun (Earth), in radians:
x1 = np.deg2rad(np.polyval([-1/3e5, -0.0001603, 35999.050340, 357.52772], jce))
#mean anomaly of the moon, in radians:
x2 = np.deg2rad(np.polyval([1./56250, 0.0086972, 477198.867398, 134.96298], jce))
#moon's argument of latitude, in radians:
x3 = np.deg2rad(np.polyval([1./327270, -0.0036825, 483202.017538, 93.27191], jce))
#Longitude of the ascending node of the moon's mean orbit on the ecliptic
# measured from the mean equinox of the date, in radians
x4 = np.deg2rad(np.polyval([1./45e4, 0.0020708, -1934.136261, 125.04452], jce))
x = (x0, x1, x2, x3, x4)
dp = 0.0
for y, ab in zip(_sp._NLOY_, _sp._NLOab_):
a,b = ab
dp += (a + b*jce)*np.sin(np.dot(x, y))
dp = np.rad2deg(dp)/36e6
de = 0.0
for y, cd in zip(_sp._NLOY_, _sp._NLOcd_):
c,d = cd
de += (c + d*jce)*np.cos(np.dot(x, y))
de = np.rad2deg(de)/36e6
e = _sp.ecliptic_obliquity(_sp.julian_millennium(jce), de)
return dp, e
@staticmethod
def abberation_correction(R):
"""Calculate the abberation correction (delta_tau, in degrees) given the Earth Heliocentric Radius (in AU)"""
return -20.4898/(3600*R)
@staticmethod
def sun_longitude(helio_pos, delta_psi):
"""Calculate the apparent sun longitude (lambda, in degrees) and geocentric longitude (beta, in degrees) given the earth heliocentric position and delta_psi"""
L,B,R = helio_pos
theta = L + 180 #geocentric latitude
beta = -B
ll = theta + delta_psi + _sp.abberation_correction(R)
return ll, beta
@staticmethod
def greenwich_sidereal_time(jd, delta_psi, epsilon):
"""Calculate the apparent Greenwich sidereal time (v, in degrees) given the Julian Day"""
jc = _sp.julian_century(jd)
#mean sidereal time at greenwich, in degrees:
v0 = (280.46061837 + 360.98564736629*(jd - 2451545) + 0.000387933*(jc**2) - (jc**3)/38710000) % 360
v = v0 + delta_psi*np.cos(np.deg2rad(epsilon))
return v
@staticmethod
def sun_ra_decl(llambda, epsilon, beta):
"""Calculate the sun's geocentric right ascension (alpha, in degrees) and declination (delta, in degrees)"""
l, e, b = map(np.deg2rad, (llambda, epsilon, beta))
alpha = np.arctan2(np.sin(l)*np.cos(e) - np.tan(b)*np.sin(e), np.cos(l)) #x1 / x2
alpha = np.rad2deg(alpha) % 360
delta = np.arcsin(np.sin(b)*np.cos(e) + np.cos(b)*np.sin(e)*np.sin(l))
delta = np.rad2deg(delta)
return alpha, delta
@staticmethod
def sun_topo_ra_decl_hour(latitude, longitude, elevation, jd, delta_t = 0):
"""Calculate the sun's topocentric right ascension (alpha'), declination (delta'), and hour angle (H')"""
jde = _sp.julian_ephemeris_day(jd, delta_t)
jce = _sp.julian_century(jde)
jme = _sp.julian_millennium(jce)
helio_pos = _sp.heliocentric_position(jme)
R = helio_pos[-1]
phi, sigma, E = latitude, longitude, elevation
#equatorial horizontal parallax of the sun, in radians
xi = np.deg2rad(8.794/(3600*R)) #
#rho = distance from center of earth in units of the equatorial radius
#phi-prime = geocentric latitude
#NB: These equations look like their based on WGS-84, but are rounded slightly
# The WGS-84 reference ellipsoid has major axis a = 6378137 m, and flattening factor 1/f = 298.257223563
# minor axis b = a*(1-f) = 6356752.3142 = 0.996647189335*a
u = np.arctan(0.99664719*np.tan(phi)) #
x = np.cos(u) + E*np.cos(phi)/6378140 #rho sin(phi-prime)
y = 0.99664719*np.sin(u) + E*np.sin(phi)/6378140 #rho cos(phi-prime)
delta_psi, epsilon = _sp.nutation_obliquity(jce) #
llambda, beta = _sp.sun_longitude(helio_pos, delta_psi) #
alpha, delta = _sp.sun_ra_decl(llambda, epsilon, beta) #
v = _sp.greenwich_sidereal_time(jd, delta_psi, epsilon) #
H = v + longitude - alpha #
Hr, dr = map(np.deg2rad,(H,delta))
dar = np.arctan2(-x*np.sin(xi)*np.sin(Hr), np.cos(dr)-x*np.sin(xi)*np.cos(Hr))
delta_alpha = np.rad2deg(dar) #
alpha_prime = alpha + delta_alpha #
delta_prime = np.rad2deg(np.arctan2((np.sin(dr) - y*np.sin(xi))*np.cos(dar), np.cos(dr) - y*np.sin(xi)*np.cos(Hr))) #
H_prime = H - delta_alpha #
return alpha_prime, delta_prime, H_prime
@staticmethod
def sun_topo_azimuth_zenith(latitude, delta_prime, H_prime, temperature=14.6, pressure=1013):
"""Compute the sun's topocentric azimuth and zenith angles
azimuth is measured eastward from north, zenith from vertical
temperature = average temperature in C (default is 14.6 = global average in 2013)
pressure = average pressure in mBar (default 1013 = global average)
"""
phi = np.deg2rad(latitude)
dr, Hr = map(np.deg2rad,(delta_prime, H_prime))
P, T = pressure, temperature
e0 = np.rad2deg(np.arcsin(np.sin(phi)*np.sin(dr) + np.cos(phi)*np.cos(dr)*np.cos(Hr)))
tmp = np.deg2rad(e0 + 10.3/(e0+5.11))
delta_e = (P/1010.0)*(283.0/(273+T))*(1.02/(60*np.tan(tmp)))
e = e0 + delta_e
zenith = 90 - e
gamma = np.rad2deg(np.arctan2(np.sin(Hr), np.cos(Hr)*np.sin(phi) - np.tan(dr)*np.cos(phi))) % 360
Phi = (gamma + 180) % 360 #azimuth from north
return Phi, zenith
@staticmethod
def norm_lat_lon(lat,lon):
if lat < -90 or lat > 90:
#convert to cartesian and back
x = cos(deg2rad(lon))*cos(deg2rad(lat))
y = sin(deg2rad(lon))*cos(deg2rad(lat))
z = sin(deg2rad(lat))
r = sqrt(x**2 + y**2 + z**2)
lon = rad2deg(arctan2(y,x)) % 360
lat = rad2deg(arcsin(z/r))
elif lon < 0 or lon > 360:
lon = lon % 360
return lat,lon
@staticmethod
def topo_pos(t,lat,lon,elev,temp,press,dt):
"""compute RA,dec,H, all in degrees"""
lat,lon = _sp.norm_lat_lon(lat,lon)
jd = _sp.julian_day(t)
RA, dec, H = _sp.sun_topo_ra_decl_hour(lat, lon, elev, jd, dt)
return RA, dec, H
@staticmethod
def pos(t,lat,lon,elev,temp,press,dt):
"""Compute azimute,zenith,RA,dec,H all in degrees"""
lat,lon = _sp.norm_lat_lon(lat,lon)
jd = _sp.julian_day(t)
RA, dec, H = _sp.sun_topo_ra_decl_hour(lat, lon, elev, jd, dt)
azimuth, zenith = _sp.sun_topo_azimuth_zenith(lat, dec, H, temp, press)
return azimuth,zenith,RA,dec,H
def julian_day(dt):
"""Convert UTC datetimes or UTC timestamps to Julian days
Parameters
----------
dt : array_like
UTC datetime objects or UTC timestamps (as per datetime.utcfromtimestamp)
Returns
-------
jd : ndarray
datetimes converted to fractional Julian days
"""
dts = np.array(dt)
if len(dts.shape) == 0:
return _sp.julian_day(dt)
jds = np.empty(dts.shape)
for i,d in enumerate(dts.flat):
jds.flat[i] = _sp.julian_day(d)
return jds
def arcdist(p0,p1,radians=False):
"""Angular distance between azimuth,zenith pairs
Parameters
----------
p0 : array_like, shape (..., 2)
p1 : array_like, shape (..., 2)
p[...,0] = azimuth angles, p[...,1] = zenith angles
radians : boolean (default False)
If False, angles are in degrees, otherwise in radians
Returns
-------
ad : array_like, shape is broadcast(p0,p1).shape
Arcdistances between corresponding pairs in p0,p1
In degrees by default, in radians if radians=True
"""
#formula comes from translating points into cartesian coordinates
#taking the dot product to get the cosine between the two vectors
#then arccos to return to angle, and simplify everything assuming real inputs
p0,p1 = np.array(p0), np.array(p1)
if not radians:
p0,p1 = np.deg2rad(p0), np.deg2rad(p1)
a0,z0 = p0[...,0], p0[...,1]
a1,z1 = p1[...,0], p1[...,1]
d = np.arccos(np.cos(z0)*np.cos(z1)+np.cos(a0-a1)*np.sin(z0)*np.sin(z1))
if radians:
return d
else:
return np.rad2deg(d)
def observed_sunpos(dt, latitude, longitude, elevation, temperature=None, pressure=None, delta_t=0, radians=False):
"""Compute the observed coordinates of the sun as viewed at the given time and location.
Parameters
----------
dt : array_like of datetime or float
UTC datetime objects or UTC timestamps (as per datetime.utcfromtimestamp) representing the times of observations
latitude, longitude : array_like of float
decimal degrees, positive for north of the equator and east of Greenwich
elevation : array_like of float
meters, relative to the WGS-84 ellipsoid
temperature : None or array_like of float, optional
celcius, default is 14.6 (global average in 2013)
pressure : None or array_like of float, optional
millibar, default is 1013 (global average in ??)
delta_t : array_like of float, optional
seconds, default is 0, difference between the earth's rotation time (TT) and universal time (UT)
radians : bool, optional
return results in radians if True, degrees if False (default)
Returns
-------
coords : ndarray, (...,2)
The shape of the array is parameters broadcast together, plus a final dimension for the coordinates.
coords[...,0] = observed azimuth angle, measured eastward from north
coords[...,1] = observed zenith angle, measured down from vertical
"""
if temperature is None:
temperature = 14.6
if pressure is None:
pressure = 1013
#6367444 = radius of earth
#numpy broadcasting
b = np.broadcast(dt,latitude,longitude,elevation,temperature,pressure,delta_t)
res = np.empty(b.shape+(2,))
res_vec = res.reshape((-1,2))
for i,x in enumerate(b):
res_vec[i] = _sp.pos(*x)[:2]
if radians:
res = np.deg2rad(res)
return res
def topocentric_sunpos(dt, latitude, longitude, temperature=None, pressure=None, delta_t=0, radians=False):
"""Compute the topocentric coordinates of the sun as viewed at the given time and location.
Parameters
----------
dt : array_like of datetime or float
UTC datetime objects or UTC timestamps (as per datetime.utcfromtimestamp) representing the times of observations
latitude, longitude : array_like of float
decimal degrees, positive for north of the equator and east of Greenwich
elevation : array_like of float
meters, relative to the WGS-84 ellipsoid
temperature : None or array_like of float, optional
celcius, default is 14.6 (global average in 2013)
pressure : None or array_like of float, optional
millibar, default is 1013 (global average in ??)
delta_t : array_like of float, optional
seconds, default is 0, difference between the earth's rotation time (TT) and universal time (UT)
radians : bool, optional
return results in radians if True, degrees if False (default)
Returns
-------
coords : ndarray, (...,3)
The shape of the array is parameters broadcast together, plus a final dimension for the coordinates.
coords[...,0] = topocentric right ascension
coords[...,1] = topocentric declination
coords[...,2] = topocentric hour angle
"""
if temperature is None:
temperature = 14.6
if pressure is None:
pressure = 1013
#6367444 = radius of earth
#numpy broadcasting
b = np.broadcast(dt,latitude,longitude,elevation,temperature,pressure,delta_t)
res = np.empty(b.shape+(2,))
res_vec = res.reshape((-1,2))
for i,x in enumerate(b):
res_vec[i] = _sp.topo_pos(*x)
if radians:
res = np.deg2rad(res)
return res
def sunpos(dt, latitude, longitude, elevation, temperature=None, pressure=None, delta_t=0, radians=False):
"""Compute the observed and topocentric coordinates of the sun as viewed at the given time and location.
Parameters
----------
dt : array_like of datetime or float
UTC datetime objects or UTC timestamps (as per datetime.utcfromtimestamp) representing the times of observations
latitude, longitude : array_like of float
decimal degrees, positive for north of the equator and east of Greenwich
elevation : array_like of float
meters, relative to the WGS-84 ellipsoid
temperature : None or array_like of float, optional
celcius, default is 14.6 (global average in 2013)
pressure : None or array_like of float, optional
millibar, default is 1013 (global average in ??)
delta_t : array_like of float, optional
seconds, default is 0, difference between the earth's rotation time (TT) and universal time (UT)
radians : bool, optional
return results in radians if True, degrees if False (default)
Returns
-------
coords : ndarray, (...,5)
The shape of the array is parameters broadcast together, plus a final dimension for the coordinates.
coords[...,0] = observed azimuth angle, measured eastward from north
coords[...,1] = observed zenith angle, measured down from vertical
coords[...,2] = topocentric right ascension
coords[...,3] = topocentric declination
coords[...,4] = topocentric hour angle
"""
if temperature is None:
temperature = 14.6
if pressure is None:
pressure = 1013
#6367444 = radius of earth
#numpy broadcasting
b = np.broadcast(dt,latitude,longitude,elevation,temperature,pressure,delta_t)
res = np.empty(b.shape+(5,))
res_vec = res.reshape((-1,5))
for i,x in enumerate(b):
res_vec[i] = _sp.pos(*x)
if radians:
res = np.deg2rad(res)
return res
def main(args):
az, zen, ra, dec, h = sunpos(args.t, args.lat, args.lon, args.elev, args.temp, args.p, args.dt, args.rad)
if args.csv:
#machine readable
print('{t}, {dt}, {lat}, {lon}, {elev}, {temp}, {p}, {az}, {zen}, {ra}, {dec}, {h}'.format(t=args.t, dt=args.dt, lat=args.lat, lon=args.lon, elev=args.elev,temp=args.temp, p=args.p,az=az, zen=zen, ra=ra, dec=dec, h=h))
else:
dr='deg'
if args.rad:
dr='rad'
print("Computing sun position at T = {t} + {dt} s".format(t=args.t, dt=args.dt))
print("Lat, Lon, Elev = {lat} deg, {lon} deg, {elev} m".format(lat=args.lat, lon=args.lon, elev=args.elev))
print("T, P = {temp} C, {press} mbar".format(temp=args.temp, press=args.p))
print("Results:")
print("Azimuth, zenith = {az} {dr}, {zen} {dr}".format(az=az,zen=zen,dr=dr))
print("RA, dec, H = {ra} {dr}, {dec} {dr}, {h} {dr}".format(ra=ra, dec=dec, h=h, dr=dr))
if __name__ == '__main__':
from argparse import ArgumentParser
import datetime, sys
parser = ArgumentParser(prog='sunposition',description='Compute sun position parameters given the time and location')
parser.add_argument('--version',action='version',version='%(prog)s 1.0')
parser.add_argument('--citation',dest='cite',action='store_true',help='Print citation information')
parser.add_argument('-t,--time',dest='t',type=str,default='now',help='"now" or date and time (UTC) in "YYYY-MM-DD hh:mm:ss.ssssss" format or a (UTC) POSIX timestamp')
parser.add_argument('-lat,--latitude',dest='lat',type=float,default=51.48,help='latitude, in decimal degrees, positive for north')
parser.add_argument('-lon,--longitude',dest='lon',type=float,default=0.0,help='longitude, in decimal degrees, positive for east')
parser.add_argument('-e,--elevation',dest='elev',type=float,default=0,help='elevation, in meters')
parser.add_argument('-T,--temperature',dest='temp',type=float,default=14.6,help='temperature, in degrees celcius')
parser.add_argument('-p,--pressure',dest='p',type=float,default=1013.0,help='atmospheric pressure, in millibar')
parser.add_argument('-dt',type=float,default=0.0,help='difference between earth\'s rotation time (TT) and universal time (UT1)')
parser.add_argument('-r,--radians',dest='rad',action='store_true',help='Output in radians instead of degrees')
parser.add_argument('--csv',dest='csv',action='store_true',help='Comma separated values (time,dt,lat,lon,elev,temp,pressure,az,zen,RA,dec,H)')
args = parser.parse_args()
if args.cite:
print("Implementation: Samuel Bear Powell, 2016")
print("Algorithm:")
print("Ibrahim Reda, Afshin Andreas, \"Solar position algorithm for solar radiation applications\", Solar Energy, Volume 76, Issue 5, 2004, Pages 577-589, ISSN 0038-092X, doi:10.1016/j.solener.2003.12.003")
sys.exit(0)
if args.t == "now":
args.t = datetime.datetime.utcnow()
elif ":" in args.t and "-" in args.t:
try:
args.t = datetime.datetime.strptime(args.t,'%Y-%m-%d %H:%M:%S.%f') #with microseconds
except:
try:
args.t = datetime.datetime.strptime(args.t,'%Y-%m-%d %H:%M:%S.') #without microseconds
except:
args.t = datetime.datetime.strptime(args.t,'%Y-%m-%d %H:%M:%S')
else:
args.t = datetime.datetime.utcfromtimestamp(int(args.t))
main(args)
