def get_sun_rise_set_transit(time, latitude, longitude, how='numpy',
                             delta_t=None,
                             numthreads=4):
    """
    Calculate the sunrise, sunset, and sun transit times using the
    NREL SPA algorithm described in [1].

    If numba is installed, the functions can be compiled to
    machine code and the function can be multithreaded.
    Without numba, the function evaluates via numpy with
    a slight performance hit.

    Parameters
    ----------
    time : pandas.DatetimeIndex
        Only the date part is used
    latitude : float
    longitude : float
    delta_t : float, optional
        Difference between terrestrial time and UT1.
        By default, use USNO historical data and predictions
    how : str, optional
        Options are 'numpy' or 'numba'. If numba >= 0.17.0
        is installed, how='numba' will compile the spa functions
        to machine code and run them multithreaded.
    numthreads : int, optional
        Number of threads to use if how == 'numba'.

    Returns
    -------
    DataFrame
        The DataFrame will have the following columns:
        sunrise, sunset, transit

    References
    ----------
    [1] Reda, I., Andreas, A., 2003. Solar position algorithm for solar
    radiation applications. Technical report: NREL/TP-560- 34302. Golden,
    USA, http://www.nrel.gov.
    """
    # Added by Tony Lorenzo (@alorenzo175), University of Arizona, 2015

    pvl_logger.debug('Calculating sunrise, set, transit with spa_python code')

    lat = latitude
    lon = longitude
    delta_t = delta_t or 67.0

    if not isinstance(time, pd.DatetimeIndex):
        try:
            time = pd.DatetimeIndex(time)
        except (__HOLE__, ValueError):
            time = pd.DatetimeIndex([time, ])

    # must convert to midnight UTC on day of interest
    utcday = pd.DatetimeIndex(time.date).tz_localize('UTC')
    unixtime = utcday.astype(np.int64)/10**9

    spa = _spa_python_import(how)

    transit, sunrise, sunset = spa.transit_sunrise_sunset(
        unixtime, lat, lon, delta_t, numthreads)

    # arrays are in seconds since epoch format, need to conver to timestamps
    transit = pd.to_datetime(transit, unit='s', utc=True).tz_convert(
        time.tz).tolist()
    sunrise = pd.to_datetime(sunrise, unit='s', utc=True).tz_convert(
        time.tz).tolist()
    sunset = pd.to_datetime(sunset, unit='s', utc=True).tz_convert(
        time.tz).tolist()

    result = pd.DataFrame({'transit': transit,
                           'sunrise': sunrise,
                           'sunset': sunset}, index=time)

    return result
dataset/ETHPy150Open pvlib/pvlib-python/pvlib/solarposition.py/get_sun_rise_set_transit