The Universe is full of sophisticated and extraordinary shapes made with interstellar matter. Some of them are well known – Pillars of Creation in M16 or Crab nebula in Taurus. But some of them are less popular, although they still look amazing. One of such forgotten shapes is Sharpless 2-86 (or NGC6820) emission nebula in Vulpecula. This molecular hydrogen cloud surrounds the NGC6823 open cluster and is located about 6,000 light-years away. Weel known M27 Dumbbell planetary nebula can be found only three degrees to the east.
The center of the NGC6823 cluster formed about two million years ago – so these bright, young stars are really fresh. But the outer parts of this cluster contains even younger stars. NGC6823 cluster forms the core of the Vulpecula OB1 stellar association. The most striking feature of Sh2-86 hydrogen cloud is a trunk-like pillar that spans from the east toward the star cluster. Such pillars of gas and dust are probably formed by stellar winds and radiation from the hot massive stars. Some dark clouds and Bok globules are also visible in the NGC6380 nebula.
It has been already seven years since I pointed my telescope to this region for the first time. I have been using 6 inches newtonian and Canon 450D modified camera and captured almost 11 hours of subframes. This year I used my main telescope – Meade ACF 10″ f/10 with Astro Physics CCDT67 reducer and again collected about 11 hours of exposures. But this time with a QHY163M camera and hydrogen alpha narrowband filter. Both transparency and seeing were average during this capture.
I personally like the processing of monochromatic images, especially made with a hydrogen alpha narrowband filter. Lack of color makes all the shapes and shades very distinct and obvious because the brain is not distracted by hue information. The processing of single-channel images is also not extremely demanding. What is definitely worth doing is removing the stars and processing starless image separately (obtained for example with Starnet tool), and then merging with the star’s image. Stars may be shrunk if that is necessary.
Below is colored image merged with stars image captured with RGB filters.
Image technical data: Date: 9-21 September, 2020 Location: Nieborowice, Poland Telescope: Meade ACF 10" Corrector: AP CCDT67 Camera: QHY163M, gain 100 Mount: SW EQ6 Guiding: Evostar 72 + ASI290MM Exposure: Ha 310x2 minutes Conditions: seeing medium, transparency medium
