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The Cave Nebula

The Cave Nebula in Cepheus The Cave Nebula in Cepheus ©2016 Frederick Steiling
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Target Information
Main Target Designations Sh2-155
RA Center 22h 56m 25.773s
DEC Center +62° 34' 03.85"
Rotation 1.234°
LHαRGB 60’/870'/112.5'/112.5'/127.5'
L subframes 6x600" @ 1x1
Hα subframes 29x1800" @ 1x1
R/G/B subframes 15/15/17 x 450" @ 1x1
Total Integration 21hrs 22min 30sec
Date(s) of acquisition 22Jul2016, 17Aug2016, 21Aug2016, 22Aug2016, 01Sep2016, 02Sep2016
Locations Whiteside, MO
Imager SBIG STF-8300M
Telescope/Lens Orion 8" f/3.9 Astrograph
Mount Celestron CGEM (DIY Hypertuned)
Guiding Apparatus OAG-8300
Guiding Camera QHY5L-II
Filter Wheel FW5-8300
Wide Filters Astronomik LRGB
Narrow Filters Astronomik 12nm Hα
Coma Corrector Baader MPCC Mark III
Collimator Howie Glatter 650nm laser
Focusing Moonlite CR with V2 High-res Stepper
Acquisition Sequence Generator Pro
Guiding PHD2
Processing PixInsight 1.8

As we move out of August, the arms and center of the Milky Way remain high in the sky early in the night, and in many places you turn, you'll find bursting star formation regions like that of the Cave Nebula.  Cataloged as Sharpless 2-155, the Cave rises from the dark molecular cloud Cepheus B as a brighter, crescent-shaped HII region, an energized emission nebula that is indicative of new galactic construction.  Sitting just 2400 light years away, the Cave measures roughly 35 light years in diameter.  It's one of many very close examples of the aggressive -- and beautiful -- displays our own galaxy puts on for us for thousands and millions of years on end!

This image's detail is produced with a combination of a narrowband Hα filter that accentuates the cloud emission detail, and a wide-band luminance filter that provides the overall star profiles throughout the image.  The result is a wonderful combination that proudly displays the folds of chutes of the nebulae, while contrasting the Milky Way star density beyond the dark molecular cloud versus that which are blocked by it.  It was a new approach I took in this (my third) combination Hα/RGB image, executed by taking separate Hα (seen here) and luminance (seen here) integrations (itself produced from both luminance and RGB detail), and doing a no-rejection "maximum" integration between them, thereby maintaining the relevant details in each (seen here).  The standard RGB color is accented with a contribution as well from the Hα integration to retain good color representation throughout the clouds.

As with any other image, I simply cannot believe that we're able to capture such marvelous snapshots of the universe from where we sit.  Each time I finish the process of gathering and composing the data for a specific region, I'm reminded in kind that the universe is constantly evolving around us, typically unbeknownst to us.  Clouds like this may some day (or some millions or billions of years from now) form an area much like that of our own solar system.  As Carl Sagan famously said, "We are a way for the cosmos to know itself".  In this image, as in any other, we really are witnessing universal history.  Let's keep watching it unfold!

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