code: public function setTime($hour, $min, $sec)
      {
          $status = IAU::Tf2d('+', (int)$hour, (int)$min, (float)$sec, $days);
          $this->checkTime($status);  // Check time is valid
  
          $this->dayFrac = $days;  // Only set the day fraction
          return $this;
      }
docs: Sets the time of this instance
  
  @param  int   $hour Hour
  @param  int   $min  Minute
  @param  float $sec  Second
  
  @return static