sun_position.py 文件源码

def eot(hUTC, dayofyear, year):
    """equation of time, ie the discrepancy between true solar time and
    local solar time

    Args:
        dayofyear: (int) the day of year

    Returns:
        (float) the eot disccrepancy (in hour)

    Details:
         Michalsky, J. J. "The Astronomical Almanac's Algorithm for Approximate
         Solar Position (1950-2050)". Solar Energy. Vol. 40, No. 3, 1988;
         pp. 227-235, USA

    """
    jd = julian_date(hUTC, dayofyear, year)
    n = jd - 2451545
    # mean longitude (deg)
    L = numpy.mod(280.46 + 0.9856474 * n, 360)
    ra = right_ascension(hUTC, dayofyear, year)

    return (L - ra) / 15.