intru function to calculate the pointing correction

[louisbondonneau]

def pointing_correction(beam_coord):
    """ Pointing correction from a given SkyCoord in altaz.
        :param beam_coord:
            SkyCoord object of the pointing in altaz.
        :type beam_coord: :class: ~astropy.coordinates.sky_coordinate.SkyCoord
        :returns: delta_az and delta_alt in deg
        :rtype: :array of float
    """

    if not (beam_coord.name == 'altaz'):
            print("ERROR: this coord need to be in altaz")

    sav_data = readsav('cor_azel.sav')
    delta_alt_data = sav_data['del_cor']
    delta_az_data = sav_data['daz_cor']
    alt_vevctor = np.linspace(15, 90, 76)
    az_vevctor = np.linspace(0, 360, 361)
    delta_alt_func = interpolate.interp2d(az_vevctor, alt_vevctor, delta_alt_data, kind='cubic')
    delta_az_func = interpolate.interp2d(az_vevctor, alt_vevctor, delta_az_data, kind='cubic')
    delta_alt = delta_alt_func(beam_coord.az.deg, beam_coord.alt.deg)
    delta_az = delta_az_func(beam_coord.az.deg, beam_coord.alt.deg)
    return (delta_alt*u.deg/60., delta_az*u.deg/60.)