I would guess that you should leave it uncovered, but 200 Celsius is about 392 Fahrenheit. If you cook it that high you should make sure it stays moist. Maybe a foil tent for the first half of cooking, then uncover and make sure that the outside is well oiled.

If you have a rack in your roasting tray that will keep the roast above the bottom of the pan you could put some water in the pan. It will help keep the roast moist.

Save me some leftovers!

Joan