I took my first galaxy pair: M81 (Bode’s Galaxy) and M82 (Cigar Galaxy). This was a perfect fit for my new Astro-Tech AT115EDT telescope. I just got it and only experimented with one other galaxy before this: NGC 2903.

In short, even though I think this came out pretty good, I found this galaxy pair hard to take, especially in my light-polluted suburb 14 miles from New York City.

About M81 M82 Galaxy Pair

M81, otherwise known as Bode’s Galaxy (right), and M82, otherwise known as Cigar Galaxy (left), are two galaxies in the Ursa Major constellation (home of the Big Dipper), located approximately 12 million light-years away from Earth. As neighbors, they share a fascinating history marked by interactions and mutual influence. Over time, M81 and M82 have interacted with each other because of their proximity, with their gravitational attraction affecting the structure and star formation processes in both galaxies. Around 100-200 million years ago, the two galaxies underwent a close encounter, causing M81’s gravitational pull to strip gas and dust away from M82. This event ignited intense star formation in M82, transforming it into a starburst galaxy, which is visually apparent because of the amount of Hydrogen Alpha–the intense red in the galaxy. The interaction also caused tidal forces to warp M81’s spiral structure and triggered star formation in its outer arms, which you can see by the red rings in its spiral arms.

M81 is home to a supermassive black hole, approximately 70 million times the mass of our Sun, at its core. This black hole is actively consuming material from its surroundings, releasing powerful jets of energy. M82 is known for its intense starburst activity, with stars forming at a rate 10 times greater than in our own Milky Way galaxy. This rapid star formation generates powerful winds that blow gas and dust out of the galaxy, as you can see with the “red wings” that are extending off M82.

In the next few billion years, their continuing gravitational encounters will cause a merger, and a single galaxy will remain.

Challenges shooting Bode’s and Cigar Galaxies

As with any astrophotography project, I encountered a few challenges while shooting M81 and M82 that I wanted to share.

Challenge 1: Light Pollution

To mitigate my light pollution issue, I planned well. I took this picture near the meridian, which has less light pollution. I also imaged on moonless nights. Out of the camera, these photos were still riddled with light pollution, especially the Luminance subs. There was another trick, though–Dynamic Background Extraction in Pixinsight, which works extremely well for removing light pollution. Out of the camera, I’d say my subs were not bad for somebody living in a Bortle 9 zone. See below.

Challenge 2: Adding Ha to a Broadband Image

Adding Ha to a galaxy was something I had never done before. This was a very unique process and I’m providing links to tutorial’s I watched and what ultimately helped me get it right. To my surprise, it wasn’t as easy as I thought. I tried  Visible Dark’s simple technique several times, but it wasn’t working out as I wanted it to. I then tried James Lamb’s technique, which worked for the first time. This technique was more laborious, but it worked much better. I referenced this video by  Paulyman Astro  which explains James Lamb’s technique very well.

Challenge 3: Bad Flats & Limited Time

Unfortunately, I could only get about 13 hours of data when I wish I could have captured 20. My backyard horizon window was closing and there were many cloudy nights. I also had many problems with my flats not removing photo flaws, which I could not fix. Due to this, I threw away a good 4 hours of integration time.

Astrophotography Notes for Next Time Shooting M81 M82

I want to shoot more luminance to bring out the Flux Nebula, which is like interstellar dust surrounding and connecting both galaxies; this photo has a little bit but is hardly noticeable. Doing so will probably take another 5-7 hours of data for that to be more prominent. It may also be impossible due to the light pollution situation.

Another issue is the star color. The stars are boring white. I may need to redo this to figure out where that went wrong, but at this point–I’ll live with it. I am obsessive-compulsive, so I’ll probably have another revision for this in the future.

Pixinsight Steps & Data for M81 & M82

Here are the steps that I took in Pixinsight to do this. I brought this into Photoshop for resizing and cropping only and did not make any further adjustments there.

Linear

  • Dynamic Crop on all channels separately
  • DBE on all channels separately (R, G, B, L, Ha)
  • Blur Xterminator on all channels
  • Noise Xterminator on all channels
  • Combine Ha with the red channel as outlined in  this video
  • Channel Combination for R, G,B using the new red I created that combines Ha data
  • Image Solver
  • Spectrophotometric Color Calibration
  • SCNR (to remove the green cast)
  • Masked Stretch to RGB
  • Masked Stretch to Luminance

Non-Linear

  • LRGB Combination adding the Luminance into the RGB
  • Star Xterminator
  • Color Saturation
  • Multiple Curves Transformations
  • Local Histogram Equalization
  • More Curves Transformations
  • Noise Xterminator
  • Unsharp Mask
  • Pixel Math to add the stars back in
  • Final Curves Transformation to add contrast

Image Integration Time

Below is the integration time and filters used for this photo.

FilterHours
Red1h 39m (99 x 60s)
Green1h 27m (87 x 60s)
Blue1h 29m (89 x 60s)
Luminance6h 39m (399 x 60s)
Ha1h 54m (38 x 180s)
TOTAL13h 8m

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