def sct2e(sc, sclkdp):
    """
    Convert encoded spacecraft clock ("ticks") to ephemeris
    seconds past J2000 (ET).

    http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/sct2e_c.html

    :param sc: NAIF spacecraft ID code.
    :type sc: int
    :param sclkdp: SCLK, encoded as ticks since spacecraft clock start.
    :type sclkdp: float
    :return: Ephemeris time, seconds past J2000.
    :rtype: float
    """
    sc = ctypes.c_int(sc)
    sclkdp = ctypes.c_double(sclkdp)
    et = ctypes.c_double()
    libspice.sct2e_c(sc, sclkdp, ctypes.byref(et))
    return et.value