My fave is num 4. That Triangulum galaxy (M33) is a member of the local cluster which includes the Magellanic Clouds, the Andromeda Galaxy (M31) and a number of smaller galaxies. M33 is quite easy to find in binoculars and is a surprisingly large object considering how far away it is. That photo showing all those UV sources is quite incredible. The galaxy must contain a tremendous number of ultra hot giant stars.