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Are there any "bubble" type nebulas that are easily viewable with a 10" scope? I'm sure there are some that are seen without a filter and some that are needed to be viewed with one. I'd just like to take a crack at one the next time I take my scope out,thanks!

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Well, THE Bubble Nebula (NGC 7635) in Cassiopeia is difficult to get more than a hint of the bubble-like form which gives the object its name. A narrowband filter like the Lumicon UHC, DGM NPB, or Orion Ultrablock will help somewhat, although much of what is seen is just an oval patch of haze around an 8th magnitude star, with possibly another fainter "V" shaped patch visible just to its north. On a really good night with the DGM NPB filter in my 10 inch f/5.6 Newtonian, I could get hints of the two "horns" on the ends of the fuzzy patch which form part of the bubble, but the full bubble form was not visible. The Crescent Nebula (NGC 6888, another bubble-like nebula) in Cygnus is just barely visible without a filter in an 8 inch under dark sky conditions. It appears as a small ghostly arc running right past a 7th magnitude star, with maybe a hint of other nebulosity nearby. A narrow-band filter will really bring up the contrast making it a lot easier to see, although it is still fairly faint. With filters, it may appear as a nearly complete oval ring with a faintly glowing interior. There are a few other diffuse nebulae in the sky that show a little of a bubble-like form, but for true rings or shells, your best bet would be planetary nebulae like the Ring Nebula M57. Clear skies to you.

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David W. Knisely
Hyde Memorial Observatory
http://www.hydeobservatory.info

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