public function setDate($year, $month, $day)
    {
        $status = IAU::Cal2jd((int)$year, (int)$month, (int)$day, $djm0, $djm);
        $this->checkDate($status);  // Check date is valid

        $this->jd = $djm0 + $djm;  // Only set JD, keep day frac to save time
        return $this;
    }