coordinate_support.py 文件源码

def xyz_to_uvw(xyz, ha, dec):
    """
    Rotate :math:`(x,y,z)` positions in earth coordinates to
    :math:`(u,v,w)` coordinates relative to astronomical source
    position :math:`(ha, dec)`. Can be used for both antenna positions
    as well as for baselines.

    Hour angle and declination can be given as single values or arrays
    of the same length. Angles can be given as radians or astropy
    quantities with a valid conversion.

    :param xyz: :math:`(x,y,z)` co-ordinates of antennas in array
    :param ha: hour angle of phase tracking centre (:math:`ha = ra - lst`)
    :param dec: declination of phase tracking centre.
    """

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

    # Two rotations:
    #  1. by 'ha' along the z axis
    #  2. by '90-dec' along the u axis
    u = x * numpy.cos(ha) - y * numpy.sin(ha)
    v0 = x * numpy.sin(ha) + y * numpy.cos(ha)
    w = z * numpy.sin(dec) - v0 * numpy.cos(dec)
    v = z * numpy.cos(dec) + v0 * numpy.sin(dec)

    return numpy.hstack([u, v, w])