M24 is a patch of Milky Way, a clumping of stars within our own galaxy and easily visible with the unaided eye. Within it is the tiny open cluster NGC6603. At one time it was thought that NGC6603 was the real M24, however Messier's description quite clearly refers to something much larger and more impressive than NGC6603. The tiny cluster is clearly visible in the photograph below the bottom centre bright star. Given Messier's optics, it is quite possible that he could not even see the cluster.