coordinate_support.py 文件源码

def xyz_at_latitude(local_xyz, lat):
    """
    Rotate local XYZ coordinates into celestial XYZ coordinates. These
    coordinate systems are very similar, with X pointing towards the
    geographical east in both cases. However, before the rotation Z
    points towards the zenith, whereas afterwards it will point towards
    celestial north (parallel to the earth axis).

    :param lat: target latitude (radians or astropy quantity)
    :param local_xyz: Array of local XYZ coordinates
    :return: Celestial XYZ coordinates
    """

    x, y, z = numpy.hsplit(local_xyz, 3)

    lat2 = numpy.pi / 2 - lat
    y2 = -z * numpy.sin(lat2) + y * numpy.cos(lat2)
    z2 = z * numpy.cos(lat2) + y * numpy.sin(lat2)

    return numpy.hstack([x, y2, z2])