Messier 103 is a small open cluster of many faint stars in Cassiopeia. It was discovered on 27 March 1781 by Pierre Méchain, but later added as Charles Messier's last deep-sky object in his catalogue.1
Star clusters are not always that interesting - but with a full moon - and in Oslo skies - they're about all you can get. And this one has some really nice colours that even I can see.