NGC 6888 - The Crescent Nebula in RGB OSC
Date: August 29, 2019
Cosgrove’s Cosmos Catalog ➤#0006
NGC 6888 - The Crescent Nebula that was created with mixed OSC RGB data. (click to enlarge)
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About the Target
NGC 6888 - The Cresent Nebula. This is an emission nebula located about 5000 light-years away in the constellation of Cygnus, the Swan.
About the Project
Last Night's Effort - after a string of problems with my setup, I was finally able to take advantage of the clear night skies. This is pretty faint and a challenge for me. To capture it, you need longer exposures and more of them. Since my imaging was done through the trees, this can be tough as I have a limited timing window for any object. I planned to capture 50 3-minute long exposures, along with another 80 or so flat, dark, and bias calibration frames. Well, I got 32, and then an unexpected cloud cover rolled in and shut me down around 2:30 am. I was still able to get all of the calibration frames, though. I did not capture all the detail I was targeting - but I can capture more on other nights and add them to the stack here (installment plan photography!)
Even still - I was pretty pleased with how this came out compared to some of my earlier efforts!
The Location in the Sky
IAU/Sky & Telescope Constellation Chart for Cygnus, showing the Crescent Nebula’s location indicated by a yellow arrow.
Capture Details
Light Frames
32 x 180 seconds
Total of 1.6 hours
Cal Frames
80 x 2 seconds Bias exposures
80 x 180 darks
80 flats
Capture Hardware
Scope: William Optics 132mm f/7 FLT APO Refractor
Guide Scope: William Optics 50mm Guidescope
Mount: Ioptron CEM 60
Tripod: Ioptron Tri-Pier
Camera: ZWO ASI294MC-Pro
Guide Camera: ZWO ASI290MM-Mini
Polar Alignment Camera: Polemaster
Software
Capture Software: PHD2 Guider, Sequence Generator Pro controller
Image Processing: Photoshop - assisted by Coffee, extensive processing indecision and second-guessing, editor regret and much swearing…..
I was still learning to use the main rig, when I soon made my first modification. I was doing the Polar Alignment the old fashioned way - using an illuminated polar scope. This caused me to kneel down on the driveway and look up through the polar axis. This was killing my knees, my back and my neck! I hated it and I was sure I was not getting very good alignments with it…..