| Description | This open cluster was discovered by Messier himself (#10) and cataloged on June 20, 1764. It continues his exploration of the southern sky in the area of Sagittarius, but now at a higher declination. Presumably, in the 18th century the star field would have been visible even from Paris, given limited light pollution. Messier's notation makes it clear that his telescope could resolve these stars: "The stars of this cluster are very close to one another." <--> This is one of my favorite OCs, significantly because of its background which contains a dense cloud of stars mottled by dark nebulae. In addition while the annotation makes it clear that the boundaries of the cluster are fairly small circle (Messier's FOV being pretty narrow), the overall star grouping is much larger and more interesting, appearing like a goose with wings spread wide. I've included an earlier observation of M23 in the gallery, captured with my EdgeHD. |
