Messier 2 is probably the weightier globular cluster of the late-summer/early storing sky, stuff a big and unexceptionable telescopic target that can moreover be swept up through 10 x 50 binoculars. It’s special too in that its individual stars are crammed together expressly tightly.
How to observe:
Messier 2 (NGC 7089) shines at magnitude 6.4 and sports a healthy unveiled diameter of 16’. These are impressive numbers, though Messier 2’s impact is tempered a little by its place within the southern constellation of Aquarius, the Water Bearer. Nevertheless, Messier 2 peaks in glut of a useful 35 degrees or so in upland at well-nigh 10.20pm BST mid-month, owing to its location in the far northern reaches of Aquarius; sweep for a misty patch through binoculars on a transparent, moonless night five degrees north of third-magnitude Sadalsuud (beta [b] Aquarii).
Through a small telescope Messier 2 shows an unresolved sphere virtually 5’ across. It is rated as matriculation II on the I–XII Shapley–Sawyer concentration matriculation for globular clusters, making the resolution of its individual stars a particularly nonflexible task for small- to medium-aperture telescopes. A 200mm (eight-inch) ‘scope at 200x will partially resolve M2’s increasingly outlying stars, but it will need the resolving power of a 300mm (12-inch), working at upper magnification, to pick out stars all the way to its core.
