If you say "globular" then odds are 99/100 that the first thing that will pop to mind for an amateur astronomer is Messier 13, a.k.a. the Great Globular Cluster in Hercules. Accessible from spring until fall and riding high in the summer sky it is a grand object. Sir Edmond Halley (of comet fame) was the first to note it as a naked eye object under dark skies. While I think I've seen it without optical aid once or twice it has been an averted vision thing at best.
The least bit of optical assistance, however, does make it quite apparent. One of my fondest memories is seeing it through Charles Cyrus' 10" reflector one evening at a Baltimore Astronomical Society gathering. I had always found hints of resolution in my 6" from Towson, but that evening at the Irvine Center, away from serious light pollution, it burst forth like a jewel, countless stars elbowing each other for attention. It was stunning.
As part of my project of tackling the Urban List with my 80mm Vixen scope from my home, M13 is one of the required stops. It's always an easy star hop (well, provided you don't struggle with locating the keystone) as the two 7th magnitude "sentinel" stars are easy to locate in the spotter scope. And even with such a simple boost to eyesight one can see a fuzzy something between them.
In the scope it's a round puff of smoke, fairly uniform in brightness compared to larger aperture that reveals the steady brightening to a core. With averted vision and higher magnification on a moonless night I can almost swear it just begins to resolve slightly, a few stars dancing just outside of plain view.
The least bit of optical assistance, however, does make it quite apparent. One of my fondest memories is seeing it through Charles Cyrus' 10" reflector one evening at a Baltimore Astronomical Society gathering. I had always found hints of resolution in my 6" from Towson, but that evening at the Irvine Center, away from serious light pollution, it burst forth like a jewel, countless stars elbowing each other for attention. It was stunning.
As part of my project of tackling the Urban List with my 80mm Vixen scope from my home, M13 is one of the required stops. It's always an easy star hop (well, provided you don't struggle with locating the keystone) as the two 7th magnitude "sentinel" stars are easy to locate in the spotter scope. And even with such a simple boost to eyesight one can see a fuzzy something between them.
In the scope it's a round puff of smoke, fairly uniform in brightness compared to larger aperture that reveals the steady brightening to a core. With averted vision and higher magnification on a moonless night I can almost swear it just begins to resolve slightly, a few stars dancing just outside of plain view.
For the last several weeks I have been attempting to image the cluster using my Canon t3i and the Vixen scope. The first few attempts gave less than desired outcome. Either the focus was not sharp enough or there were too many shots where there was some trailing of stars due to alignment or camera shutter vibration. But finally this week I managed to acquire about 45 minutes of 30 second images that stacked and produced the photo below. Not bad, it even shows tiny galaxy NGC 6207 (mag 11.5) in the upper left hand side. What amazing technology we have today.
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