M23

From South Dublin Astronomical Society

M23
Type	Open cluster
NGC	NGC 6494
Constellation	Sagittarius
Right Ascension	17h 56.8m
Declination	-19° 01’
Magnitude	6.9
Size	27 arc min.
Image:M23 messier image.jpg

The scattered open cluster M23 lies 4º to the northwest of the Lagoon Nebula/Trifid Nebula complex and is beautifully resolved in binoculars. If you are having a lot of trouble finding it then you just need to scan 5º to the right (west) of the M24 star cloud. Numerous faint suns are arranged in winding chains while a magnitude 6·5 blue-white star a short distance off the northwestern edge is probably unrelated. The members are strewn over roughly a half-degree of sky — a scene that led C. E. Barns in 1929 to gush that it was “a blazing wilderness of starry jewels”. Larger binoculars yield a superb view of this object. M23 was discovered by Charles Messier on June 20, 1764 and has been found to lie at a distance of 2,150 light years. Burnham, in the third volume of his Celestial Handbook, writes that the majority of the group is made up of somewhat reddened main sequence stars.