NGC6888 - The Crescent Nebula
Description: NGC6888, the Crescent Nebula, is in the constellation of Cygnus. This image was taken on August 29, 2008 from the Oregon Star Party. I shot this object for the first time at OSP last year with my C8 at F/6.7. I was surprised at how big it was, so I wanted to get a wide field shot this year. It was the last image that I took at OSP and I had some trouble getting the exposures correct. I ended up over-exposing the luminance and about a dozen stars bloomed pretty badly. And, since this was the second object of the night, I cheated on the Ha exposures and binned them 2x2 to try and beat sunrise. It was a lot of work fixing the blooms, and I think that I've still over-cooked the luminance. The Ha frames in this shot turned out pretty well, but it doesn't come across here because the star field just overwhelms the fainter parts of the surrounding nebula. Reprocessing this shot will be a good project for this winter - and I'll probably shoot it again next year at 600mm and dedicate a full night (or two) to it.
Equipment: The image was taken with an Orion ED80 telescope on a Celestron CGE mount. The camera was an SBIG ST10XME with an Astro-Physics .67 Telecompressor and Astrodon filters. The guide scope and camera were an AstroTech AT66ED refractor with an SBIG remote guide head attached to the ST10. Focusing was done manually.
Exposures: 18x120 seconds luminance binned 1x1; 9x120 seconds each red, green and blue exposures binned 2x2, 9x600 seconds Ha exposures binned 2x2.
Processing: Bias, dark & flat calibration, image registration & color registration were done in Maxim/DL. Curves, levels, LRGB combination, zone sharpening & noise reduction were done in Photoshop CS2. Gradient processing was done with GradientXTerminator.
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