NGC 2237 The Rosette Nebula

NGC2237 The Rosette NebulaClick here for an annotated version of this target.

NGC2237, also known as the Rosette Nebula in Monoceros, is an H II region in the Milky Way Galaxy. There are multiple NGC objects in this region. NGC2244 (C50) is the cluster of stars in the middle that’s associated with the nebulosity.

There are multiple NGC objects in the region like NGC 2237, NGC 2238, NGC 2239, NGC 2244, NGC 2246. However, NGC2237 is usually used to refer to the entire nebula.

The Rosette Nebula is about 100 light-years across and lies about 5000 light-years away from us.

The stars inside the Rosette was formed about four to five million years ago. The hot and fast stellar winds from these young stars have created a cavity in the center. The dark nebula in the complex is called Bok Globules. These are dense clouds of dust and gas that are under the gravitational attraction from the stars. These dense clouds block the light from the nearby stars forming the dark nebula.

Processing Info

I took over 120 subs, some at 300 and others at 600 seconds each. Between clouds and haze, I threw away 21 frames. Having more data allowed me to be selective, and I could throw out frames with high FWHM and eccentricities that I didn’t like. I stacked the 99 remaining frames along with 50 dark frames and 30 flat and dark flat frames.

The following processes were performed in PixInsight:

    • Channel Extraction
    • Linear Fit
    • Channel Combination
    • Dynamic Crop
    • Dynamic Background Extraction
    • Automatic Background Extraction
    • Background Neutralization
    • Photometric Color Calibration
    • EZ Decon
    • EZ Denoise
    • Histogram Transformation
    • LRGB Combination
    • Curves Transformation (X2 with a range mask. Inverted mask for the background and then non inverted for the target)
    • Color Saturation (X2 with a range mask. Inverted mask for the background and then non inverted for the target)
    • Curves Transformation ( Using a range mask on the edges of the nebula.)
    • SCNR (Removed Green)
    • EZ Star Reduction
    • Local Histogram Equalization (Performed with a range mask)
    • HDR Multiscale Transform

Once I found what I liked, I saved the files and went to Photoshop. I played around with the levels, vibrance, and saturation a bit. I then ran Topaz AI DeNoise. I honestly didn’t need to be that aggressive with the noise reduction, as having 11 hours of data helped reduce noise.

The area of the sky in OrionHere you can see the area of the sky in Monoceros imaged.

Acquisition Data

  • Telescope: Explore Scientific ED127 f7.5 Air-Spaced Triplet Apochromatic Refractor
  • Camera: ZWO ASI2600MC Pro
  • Guide Scope: Orion ST80
  • Guide Camera: ZWO ASI290MM Mini. Dithering every image at 1 pixel each time.
  • Mount: iOptron CEM60
  • Software: NINA for image acquisition. PixInsight used for stacking and editing. Imported to Photoshop for final touchup and watermarking.
  • Other Accessories: AstroZap Dew Heater, Starizona Apex ED 0.65x L
    Reducer/Flattener, MoonLite CFL 2.5″ Focuser, High Res Stepper Motor, V3 Controller, Pegasus Astro Power Box Advance
  • Filters: Optolong L-eNhance 2″ (54 x 300s), Optolong L-eXtreme 2″ (08 x 300s, 37 x 600s)
  • Exposure Time: 11 hours 20 minutes -20°C
  • Date: December 06, 07, 10, 12, 2020
  • Location: Voorhees State Park, NJ, United States
  • GPS Coordinates: Lat. 40.68187, Long. -74.89797
  • Temperature: 29°F/-2°C
  • Bortle Dark-Sky Scale: 4
  • Avg. Moon age: 23.51 Days
  • Avg. Moon phase: 38.00%
  • RA center: 6h 32′ 2″
  • DEC center: +4° 55′ 58″
  • Orientation: 316.165 degrees
  • Field radius: 1.174 degrees
  • Magnitude: 4.8
  • Resolution: 3720 x 2330