M4

From South Dublin Astronomical Society

M4
Type	Globular cluster
NGC	NGC 6121
Constellation	Scorpius
Right Ascension	16h 23.6m
Declination	-26° 32’
Magnitude	5.6
Size	36 arc min.
Image:M4 messier image.jpg

Although the celestial scorpion never crawls far about the skyline from our latitude, there are a number of deep sky objects within for the binocular observer. Premier amongst these is M4, a globular cluster that sits within the same field of view as Antares. Under ideal conditions, with the horizon free of summer haze, you’ll easily see the object as a patch of light just over one degree west of Antares. Large binoculars hint at a grainy structure when the sky transparency is quite good. M4 is considered one of the closest globular cluster to our Solar System, if not the closest. It lies 7,200 light years away — nearer than some of the open clusters highlighted in this handbook— and would be more prominent but for heavy obscuration by interstellar dust.