LVAS September 2017 Observer's Challenge - NGC 6905

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Apollo XX
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LVAS September 2017 Observer's Challenge - NGC 6905

Unread post by Apollo XX » Sat Sep 30, 2017 10:47 am

For the LVAS September 2017 Observer’s Challenge I was able to observe NGC 6905, also known as the Blue Flash Nebula several times. I was also able to use several different telescopes, including 8”, 12.5” and 18” reflectors.

My first exposure to 6905 came back in July at the 2017 Stellafane Convention. For the past two years, Larry Mitchell has assembled an observing list for one of the latest additions to the convention activities, which is called the Stellafane Observing Olympics. 6905 was on this year’s list and I looked at it briefly in my 8” reflector, but because I was more interested in completing the list I didn’t spend much time on it.

My second exposure to 6905 came in August on one of the darker, clearer nights of the month when I was using my 12.5” reflector. This observation was spectacular. I was taking my time this time, and I found that the nebula responded well to magnification. 6905 is nestled very nicely in a trapezium of 11th – 13th magnitude stars, and the nebulosity itself showed nice structure. I can’t recall glimpsing the 14th magnitude central star during this observation. I created my sketch of 6905 on this night at 254x.

My final exposure to 6905 for the challenge came on a clear, dark night in late September. On this night I was able to view 6905 through a friend’s 18” reflector, and the view was gorgeous. Because of eyepiece limitations we were restricted to 280x, but even at that power the central star was surprisingly visible with averted vision. In fact, it caught me off guard with how bright it seemed and I found myself going back and forth many times to make sure I was seeing what I was seeing. It was a thrill to catch it.

I also went back with the 8” on that September evening just to push it and see what could be done with it. Perhaps the most noticeable difference in the view was that even at 267x in the 8” scope, one of the 13th magnitude trapezium stars was not directly visible, or not readily anyway. It seemed almost wrong in a way, because the nebula looks so comfortably cradled in that trap of stars that without one it looked like it was sitting on a three legged stool.

So that’s my story. For more information on the Blue Flash Nebula and many more interesting objects, you can read about them at the Stellafane website here; ... rving.html

Mike M.
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