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I had several enjoyable observing sessions earlier this week with my 22-inch Dob from our midtown Kansas City backyard. One object that surprised me was M107, a globular cluster in Ophiuchus. This is not a difficult object from dark sites, but I had difficulty locating it from my backyard even with 22-inches of aperture ...

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M107 has low surface brightness for a globular cluster. That, coupled with the fact that it's well south of the celestial equator, makes it challenging from light-polluted sites at mid-northern latitudes.

Looking over my notes, I find that M107 and M68 are the only Messier globulars that I couldn't see through my 70-mm refractor from my local urban park. And even through my 7-inch Dob, I logged M107 as "difficult with averted vision" from that park.

By contrast, M107 is not especially hard through 15x45 binoculars at a dark site.

M68 is even tougher because it has lower surface brightness yet, and it's much farther south.

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Tony Flanders

eyeglasses
6x15 and 8x32 monoculars
8x25, 7x35, 10x30 IS, 10x50, and 15x70 binoculars
70mm and 100mm achromatic refractors
4.5", 7", and 12.5" Dobs

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