Image (merely enlarged from image above) obtained October 29-30, 2016 through RVO's Megrez 80mm refractor with Orion field-flattener lens, using a Baader-modified Canon XSi DSLR and BackyardEOS image-acquisition software – 28 of 29 carefully selected and stacked 300 and 420-second luminance frames combined with multiple dark, flat and bias calibration frames shot at ISO 1600 and totaling more than 390 minutes (150 minutes effective luminance) were used to create this image; optics driven by the Losmandy G-11 mount equipped with Ovision's precision RA worm gear, guided with a ZWO ASI 120MM Monochrome CCD camera through a 60mm guidescope using PhD2 guiding software and post-processed with DeepSkyStacker, Digital Development Process in Maxim DL Pro, NI noise reduction and Photoshop CS3 s/w.

"The Cave Nebula (Sharpless 155 or Sh2-155) is a dim and very diffuse bright emission nebula surrounded by dust. It has a radius of about 35 light-years, and is located some 2400 light-years away in the constellation of Cepheus. The nebula has gotten its nickname from the darker area, at the center left, which visually appears as a cave. The name Sharpless comes from a catalog of 312 emission nebulae (H II regions). The first edition was published by Stewart Sharpless in 1953 with 142 objects (Sh1) and the second and final version was published in 1959 with 312 objects (Sh2). This crescent-shaped star-forming region (HII region) that consists of double ionized hydrogen, lies within and arose from the large molecular cloud known as Cepheus B, which contains reflection, emission, and dark nebulae. The stars within the Cave Nebula are very young, mostly less than 100,000 years old, while new stars are born at a high rate within the dust clouds of the nebula. Two bright stars (HD 217061 and HD 217086) illuminate the bright ridges of the Cave Nebula."

As a side-note, clicking on the above text link takes you not only to a nice description of the Cave Nebula and region, but also introduces you to a absolutely spectacular image by Adam Block; the same Adam Block that gave me my first instruction into CCD-type astrophotography when he was in charge of the Kitt Peak National Observatory outreach program. I was privileged to spend one night at the telescope with him, actually taking pictures. Really though, he took the pictures while I watched and did what I was told. It was one of the most intense learning experiences of my life. He moved on to become the founder of the stargazing programs and essential creative director of the University of Arizona's Mt. Lemmon SkyCenter. So, Adam Block is now, just a few years later, one of the most renowned and sought-after astrophotographers in the world! Thanks, Adam!

[copyright Rabbit Valley Observatory/Willis Greiner, 2016 -- all rights reserved]