M103 is a very distant open cluster in the constellation Cassiopeia.
The spikes on the brigher stares were induced by running two strings across the front of the telescope. Normally SCT telescopes like the EdgeHD 11 used for this photo do not cause diffraction spikes. The stars are ideally perfectly round with no spikes. But for clusters, spikes can sometimes highlight the stars so I used the strings to induce them for this picture.