Three in One
Globulars M9, NGC 6342, and NGC 6356 in the constellation of Ophiuchus all lie within a 2° circle. This Sky & Telescope illustration shows stars down to 10th-magnitude. The trio may be found 14° northeast of Antares in Scorpius. Click on the image to see the complete chart.
Moving north and west into Ophiuchus, we come across a trio of globulars:
M9, NGC 6342, and
NGC 6356. As
Sky & Telescope associate editor Gary Seronik comments, "These are three of my favorite globulars because I can view all of them with my 8-inch f/6 Newtonian reflector and a low-power eyepiece. To the best of my knowledge, these are the only three globulars close enough together to fit into a single field with this scope."
My own Meade 8-inch f/6 Newtonian could not resolve M9 at 174x
on an excellent night, though it did have a granular appearance. While its distance is comparable to the well-known globular M13 in Hercules, the stars of M9 are
considerably dimmed by dust in the plane of the Milky Way — some of which can be seen as the ¾°-long dark nebula Barnard 64. This nebulosity wraps around the western side of the cluster, extending from ½° northwest of
M9 southward to the cluster's western edge before it broadens just south of the globular.
A little more than a degree south-southeast of M9 is NGC 6342.
At 116x with my 8-inch scope this small 10th-magnitude cluster showed a slight brightening toward its center. I was able to find it with my Astroscan, a 4¼-inch wide-field reflector telescope, using only 34x.
Diminutive NGC 6356 lies 1.3° northeast of M9. It is estimated to be 48,000 light-years distant, but still remains a viable target for small scopes.
Courtesy Digital Sky Survey.
The third member of this trio, NGC 6356, is 1.3° northeast of M9. It's a condensed object with a bright center. The distance to NGC 6356 is estimated at 48,000 light-years, which makes it the most distant object on our tour and puts it about 20,000 light-years farther away than its two neighbors. Yet it can be viewed with a small telescope! As a youth, I saw it with my 2.4-inch refractor, guided by a Walter Scott Houston column in the July 1962 issue of
Sky & Telescope. At that time Houston's column primarily featured clusters, galaxies, and nebulae from the Messier catalog; NGC objects were a rare exception. I still remember thinking that this was pretty hot stuff — finding an NGC globular!
