def spkacs(targ, et, ref, abcorr, obs):
    """
    Return the state (position and velocity) of a target body
    relative to an observer, optionally corrected for light time
    and stellar aberration, expressed relative to an inertial
    reference frame.

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

    :param targ: Target body.
    :type targ: int
    :param et: Observer epoch.
    :type et: float
    :param ref: Inertial reference frame of output state.
    :type ref: str
    :param abcorr: Aberration correction flag.
    :type abcorr: str
    :param obs: Observer.
    :type obs: int
    :return:
            State of target,
            One way light time between observer and target,
            Derivative of light time with respect to time.
    :rtype: tuple
    """
    targ = ctypes.c_int(targ)
    et = ctypes.c_double(et)
    ref = stypes.stringToCharP(ref)
    abcorr = stypes.stringToCharP(abcorr)
    obs = ctypes.c_int(obs)
    starg = stypes.emptyDoubleVector(6)
    lt = ctypes.c_double()
    dlt = ctypes.c_double()
    libspice.spkacs_c(targ, et, ref, abcorr, obs, starg, ctypes.byref(lt),
                      ctypes.byref(dlt))
    return stypes.cVectorToPython(starg), lt.value, dlt.value