Saturday, July 24, 2021

NGC 6946 - Fireworks Galaxy

NGC 6946 a.k.a. The Fireworks Galaxy is described as a face-on intermediate spiral galaxy bordering Cepheus and Cygnus at a distance 25 million light-years. It is approximately 40,000 light-years across and contains about 100 billion stars. Although it has a small bright nucleus, the galaxy as a whole is very faint as it is close to the galactic plane of the Milky Way. I could barely see it in subframes during imaging. It is classified as a starburst galaxy (star-forming) due to its high rate star formation. It has ten times the star formation as the Milky Way yet is half the size hence the Fireworks nickname. The arms contain many dense areas where star-formation is occurring - the upper-left arm shows a very prominent region where it is occurring.

This is my second image with the new setup (Edge & ASI294MC) and is the first time I ever imaged this object. It was a bit tough to process given the great amount of stars and galactic material in between it and us so a lot of star reduction was in order. I learned a lot since my previous image about this setup and the Asiair so, hopefully there is improvement. I did add another ~1.5mm to the backspace and the stars were not as elongated in the corners on the uncropped raw data. I did try adding 4.5mm for my latest object but that is in process. I believe I have decent autofocus settings now as I get a good V-curve and also checking and performing the collimation is easier now.

I also used the Baader Neodymium Moon & Skyglow filter rather than a plane UV/IR filter since the moon was starting to show itself. I also used the Deep Sky Stacker as PI was giving me horrible results with this camera and flats. I'll have more to say on this issue at a later date!


NGC 6946 - Fireworks Galaxy
Dates: 7-15, 7-19
Camera: ZWO ASI294MC-Pro
Telescope: Celestron EdgeHD 800
Barlow: None
Focal Length: 2032mm (native)
F/10 (native)
Focal Reducer: Celestron .7 Reducer Lens
Mount: Orion Atlas Pro
Filter Adaptor: ZWO Filter Drawer
Filter: Baader Neodymium Filter (2-inch)
Focuser: ZWO EAF
Autoguiding: ASI120 Mini attached to an Orion ST80
Exposure: L 129 x 180
Gain: 120
Offset 0
Temp: 0 C
Processing: Asiair app, DSS, PixInsight, Photoshop, Gradient Exterminator, Topaz DeNoiseAI.

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5 comments:

  1. Hi Kurt, beautiful picture!
    Can you share your workflow for this one? I collected 4.5 hours on this target this past Wednesday. I use the same camera and an 8" Celestron CPC with a focal reducer, so my setup is very similar to yours, but I can't get the blue of the galaxy to come out in my image, and the very red star to the right is not red at all for me, stars overwhelm the frame, etc.
    Thanks for posting all your useful tutorials! Great for beginners like me!
    Denis

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  2. One more question. I've read that you should never use an offset of 0, but you did for this acquisition. Why do you use a zero offset, and how does it impact the processing of the image? Thanks again!
    Denis

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    1. Yeah I have heard that before and don't know if offset does a thing. I think it used to be important with older cameras. - Cheers Kurt

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  3. Hi Denis, This is a hard object to process because it sits close the MW plane. It was a slow and subtle process to get the colors. I first did some noise reduction and star reduction in PixInsight. Then brought into photoshop for color many small color adjustment not just one thing. The biggest effect however was reducing the red which made the it more blue. Also, I did a bit more star reduction in photoshop using Noel Carbonies Astronomy Tools Action set which is a Plugin for photoshop. The key thing was many small adjustments. - Good Luck

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    Replies
    1. Thanks Kurt! I only have PixInsight so I'll keep trying small adjustments with that. I'll try reducing the red a little like you did to see what that does. Looking forward to seeing your next image!

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