https://github.com/astropy/astropy/issues/3093

def estimate_angle(coord, angle, new_frame, offset=1e-7):
    """
    https://github.com/astropy/astropy/issues/3093
    """
    delta = delta_coord(coord, angle, offset)
    new_coord = coord.transform_to(new_frame)
    new_delta = delta.transform_to(new_frame)
    return new_coord.position_angle(new_delta).deg