Telescope Reviews: Re: I need a couple of good diffuse nebulae

In Cygnus there's the supernova remnant known as the Veil nebula, which consists of NGC-6960, 6992 and NGC-6995 spread out over an area of nearly three degrees. From a good site it's evident in a 6-inch, at least the first two sections. In a ten-inch you start seeing streaks of nebulosity and NGC-6995, also known as the Witch's Broom appears.

Two other Cygnus nebula that would be good objects to show your students are the North American Nebula, also known as NGC-7000. Bring a small, wide field telescope so the outline can be made out or use a focal reducer and a low power, wide angle eyepiece. Inside this nebula is a star cluster whose young, hot and massive stars are exciting the gases into glowing. Powerful ultraviolet radiation from these stars excite atoms, which then re-emit the energy as visible light.

The other is the Cresent Nebula, also known as NGC-6888. This nebula is the ejected outer envelope of a Wolf-Rayet star that is going to explode as a supernova at any time in the next several hundred thousand years. It's already used up the hydrogen in it's core and is now a massive ball of heavier elements for which time is rapidly running out. When it goes off as a supernova, it will undoubtedly light up our skies just like the one that formed the Veil Nebula as recently as 5,000 years ago. It's an easy object for a ten-inch, and all of these nebulae I mentioned respond very well to either O-III or narrow band nebula filters.

I would then show them M-8 and M-17, two very bright diffuse nebulae around newly formed star clusters. These objects are very bright and spectacular in any telescope and are magnificent from dark sites. Like NGC-7000, they are diffuse nebulae excited into glowing from the UV light given off by the massive, hot stars that formed inside of them.

For a planetary nebula in Cygnus, there's NGC-6826. In Andromeda there is NGC-7662 and in Aquila there's the large but ring shaped NGC-6781. Don't overlook M-57 and M-27, both of which are toroidal planetary nebulae, one where we can see into the donut hole in the center, the other oriented edge on.

All of these objects are high in the sky right now as soon as it gets dark, and from my location on the Alabama Gulf Coast they get high in the sky. I hope the weather cooperates, for the past month it's been mostly cloudy and rainy here in my city.

Taras

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15-inch F/4.5 Dob under construction
10-inch F/4.5 Discovery Dob
6-inch F/8 Homebuilt Dob
4 1/4-inch F/4 Homebuilt reflector
A whole bunch of eyepieces, filters and other accessories....
One curious cat

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