private function deltaT_lastJD()
    {
        // Seek to maximum line
        $mLine = count(file($this->storage('deltat.data'))) - 1;
        $file  = new \SplFileObject($this->storage('deltat.data'));
        $file->seek($mLine);

        // Get the line until it's not empty stepping back 1 line if so
        $line = $file->getCurrentLine();
        while (trim($line) == '') {
            $file->seek($mLine);
            $line = $file->getCurrentLine();
            $mLine--;
        }

        $mLine--;
        $file->seek($mLine);
        $line = $file->getCurrentLine();

        // YMD -> JD and return
        $y = (int)substr($line, 1, 4);
        $m = (int)substr($line, 6, 2);
        $d = (int)substr($line, 9, 2);
        static::iauCal2jd($y, $m, $d, $djm0, $djm);

        return $djm0 + $djm;
    }