def convert_ephemeris_time_to_j2000_offset_utc(time):
    """TES ephemeris time is given in reference to the J2000 epoch.
    The marstime package already works in reference to the J2000 epoch, so we have
    most of the tools already.
    """
    ephemeris_offset = 0
    ephemeris_scale = 1.0 / 86400.0
    return time * ephemeris_scale + ephemeris_offset
