M4 Bright Globular Cluster

Messier 4 (also known as NGC 6121) is a bright globular cluster in the constellation Scorpius. It is visible even with small instruments. M4 is one of the easiest clusters to locate: just aim at Antares and move just 1.3° to the west; In optimal weather conditions it is even visible to the naked eye, although with extreme difficulty, while even with good binoculars it is easily observable. A 120mm telescope already resolves some of its stellar components, although most of the object remains nebulous in appearance.

M4 can be easily observed even when it is not very high on the horizon, but it must be borne in mind that it is an object located at moderately southern declinations, so in some areas of Northern Europe and Canada, close to the Arctic Circle, it is never observable; from the southern hemisphere, on the contrary, M4 is clearly visible and high on the nights of the austral winter. The best time to observe it in the evening sky is between May and August.