public static function jd($jd, TimeScale $timescale = null)
    {
        // JD -> Y-M-D H:M:S.m
        $t = [];
        IAU::D2dtf($timescale, 14, $jd, 0, $y, $m, $d, $t);

        // Create new instance from date/time components
        return new static($y, $m, $d, $t[0], $t[1], $t[2], null, $timescale);
    }