| Description | Messier discovered M18 himself (#6 so far), cataloged on June 3, 1764, commenting: "A cluster of small stars, a little below nebula No. 17, surrounded by slight nebulosity, this cluster is less obvious than the preceding, No. 16...." <--> At Dec -18, M18 is low in my southern sky, so I have to pick my times carefully and catch it "between trees". Low angles reduce transparency, and it's obvious from the misshapen stars that seeing was not very stable. Located proximate to the small Sagittarius Star Cloud, the curve of the "Swan's Neck" is outlined by a combination of bright stars and dark nebulae; otherwise, even with a short exposure, more field stars would be visible. The Swan's breast is formed by an ovoid pattern of the 7 or so largest, white stars. The Swan's tail is visible only in the full-field image, and is suggested by a triangular merging of two lines of stars, though the illusion is unconvincing if you examine it closely. |
