We explore the celestial targets around the Butterfly Cluster, M6
line along the southern edge of the brighter inner portion of the cluster. The line is terminated to the west by a solitary orange star of mag. +5.6. A 250mm instrument using a low power eyepiece shows around 100 stars. The brightness and large apparent size of M7, also known as Ptolemy’s Cluster, comes about because it’s close at 980 lightyears. SEEN IT
4 NGC 6453
Our next target is a globular cluster which is located half a degree to the westnorthwest of the centre of M7. NGC 6453 sits in a busy part of the sky and is easy to overlook. It’s a mag. +9.8 object which has an apparent diameter around 1.3° as seen through a 200mm scope. It’s a difficult object to observe well, looking more like a faint smudge than anything else. A few stars may be seen in front of the core but these are foreground objects, the globular itself is unlikely to be resolved. The reason why it’s troublesome is down to its distance from Earth, it being 31,300 lightyears away. SEEN IT
5 NGC 6528
Our next two targets are close to one another as well as being easy to find. To locate them return to the tip of the Teapot’s spout as marked by the star Alnasl (Gamma (g) Sagittarii). The first one is located 26 arcminutes north-northwest of Alnasi. Here you’ll find the mag. +9.5 globular cluster NGC 6528, but chances are you’ll have to work for it. This is a small object, just over 1 arcminute in apparent diameter through a 250mm scope; at low powers it’s easy to overlook as a fuzzy star, but at 80x and higher it looks mottled. And this is where the fun begins because you’re looking in towards the Milky Way’s core and there are many stars to be seen. SEEN IT
6 NGC 6522
Our last object has an integrated magnitude of +8.4 and it’s also easy to locate, lying 15 arcminutes to the west of NGC 6528. A 150mm scope shows it to have a well-defined core with a faint surrounding halo perhaps as large as 2 arcminutes in diameter. A 250mm scope shows the bright core to be slightly elongated. A curious dark lane cuts across the western edge of the core, running north to south. Don’t be afraid to up the power here, as NGC 6522 is 25,100 lightyears away. SEEN IT