isofit.core.sunposition

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 – datetimes converted to fractional Julian days

Return type:

ndarray

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 – Arcdistances between corresponding pairs in p0,p1 In degrees by default, in radians if radians=True

Return type:

array_like, shape is broadcast(p0,p1).shape

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) – UTC datetime objects or UTC timestamps (as per datetime.utcfromtimestamp) representing the times of observations

• latitude (array_like) – decimal degrees, positive for north of the equator and east of Greenwich

• longitude (array_like) – decimal degrees, positive for north of the equator and east of Greenwich

• elevation (array_like) – meters, relative to the WGS-84 ellipsoid

• temperature (array_like or None, optional) – celcius, default is 14.6 (global average in 2013)

• pressure (array_like or None, optional) – millibar, default is 1013 (global average in ??)

• delta_t (array_like, optional) – seconds, default is 0, difference between the earth’s rotation time (TT) and universal time (UT)

• radians ({True, False}, optional) – return results in radians if True, degrees if False (default)

Returns:

coords – 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

Return type:

ndarray, (…,2)

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) – UTC datetime objects or UTC timestamps (as per datetime.utcfromtimestamp) representing the times of observations

• latitude (array_like) – decimal degrees, positive for north of the equator and east of Greenwich

• longitude (array_like) – decimal degrees, positive for north of the equator and east of Greenwich

• elevation (array_like) – meters, relative to the WGS-84 ellipsoid

• temperature (array_like or None, optional) – celcius, default is 14.6 (global average in 2013)

• pressure (array_like or None, optional) – millibar, default is 1013 (global average in ??)

• delta_t (array_like, optional) – seconds, default is 0, difference between the earth’s rotation time (TT) and universal time (UT)

• radians ({True, False}, optional) – return results in radians if True, degrees if False (default)

Returns:

coords – 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

Return type:

ndarray, (…,3)

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) – UTC datetime objects or UTC timestamps (as per datetime.utcfromtimestamp) representing the times of observations

• latitude (array_like) – decimal degrees, positive for north of the equator and east of Greenwich

• longitude (array_like) – decimal degrees, positive for north of the equator and east of Greenwich

• elevation (array_like) – meters, relative to the WGS-84 ellipsoid

• temperature (array_like or None, optional) – celcius, default is 14.6 (global average in 2013)

• pressure (array_like or None, optional) – millibar, default is 1013 (global average in ??)

• delta_t (array_like, optional) – seconds, default is 0, difference between the earth’s rotation time (TT) and universal time (UT)

• radians ({True, False}, optional) – return results in radians if True, degrees if False (default)

Returns:

coords – 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

Return type:

ndarray, (…,5)

class Sunposition(t, lat, lon, elev, temp, p, dt, rad, csv=False)

Bases: object

Compute sun position parameters given the time and location.

lat = None

lon = None

elev = None

temp = None

p = None

dt = None

rad = None

t = None

az = None

zen = None

ra = None

dec = None

h = None

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