Messier 81 and Messier 82

Messier 81 and Messier 82Click here for an annotated version of this target.

Messier 81 (center), Messier 82 (right), and NGC3077 (left) are a trio of galaxies that belong to the M81 group of galaxies in Ursa Major. The two bright galaxies M81 and M82, are one of the most spectacular targets to look through on a low-powered eyepiece in the spring sky,

The galaxy group, which includes M81 (Bode’s Galaxy), M82 (Cigar Galaxy), NGC 3077 (Garland Galaxy), and many other Holmberg, IC, NGC, PGC, and UGC objects, is the closet galaxy group to our very own local group of galaxies which includes the Milky Way. This group and our group are together part of the Virgo Supercluster of Galaxies.

M81 is a grand design spiral galaxy that interacts gravitationally with M82, an irregular starburst galaxy. A grand design galaxy means it has well-defined spiral arms.

M82 is going through a higher than normal rate of star formation. The high rate of star formation uses up the galaxy’s molecular gas at a rate that it itself cannot sustain for much longer. It is estimated that it’ll run out of fuel supply within the next couple hundred million years at its current rate. Due to the large star formation rate, a lot of these stars are high mass stars, and they have a relatively short lifetime of 10 million years. These stars are dying and going into a supernova in the galaxy. The center of the galaxy has a few clusters of stars going off into supernovae every few decades. The supernova’s high energy puffs up the core of the galaxy, and the escaping gas causes a chimney-like effect that then expels the gas from the core.

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

Messier 81 and Messier 82Click here for an annotated version of this target.

This has been my longest project to date. I was lucky enough to gather 43 hours of data on this target. Due to the nature of how bright the target was and the sensitivity of modern CMOS cameras, most of my images had to be taken at 60-second exposure length.
Even with that sort of exposure, I noticed that I was clipping the histogram a little bit.

When I first started the project, I was doing 120 seconds for Luminance, and I def noticed some missing details in the core and the spiral structure of M81. I decided to switch to 60 seconds. This resulted in me ending up with 1873 frames to stack. Once I had the data sorted with Blink and SubFrame Selector, I put them through WBPP, NSG, and ImageIntegration. After about 60 hours, I had the masters and I was ready to start processing.

Most of the data were taken from home at my observing site in Voorhees State Park (Bortle 4). I was extremely lucky and was gifted with 5 clear nights at Cherry Springs State Park (Bortle 2) and got about 20 hours of luminance data from there.

Processing Info

The following steps were performed with the Ha, Lum, Red, Blue & Green stacked data:

  • Dynamic Crop
  • Linear Fit
  • Dynamic Backgroud Extraction

The following steps were performed to the Luminance data:

  • Deconvolution
  • EZ Denoise
  • Histogram Transformation (I intentionally clipped some of the data)

Once I had the gradients smoothed out, I started working on the Ha data to integrate that into my images. I found a very helpful tutorial on a YouTube channel, Entering into Space. I found this a very helpful tool to get me started on isolating Ha and then adding it into the Red channel. Here are the steps I took to isolate and then add the Ha.

I know that this can be done with the NBRGB combination script in PixInishgt, however this might just be a placebo, but I feel like that the script gets me better results. 

  • I created a new image by applying this formula to the Ha channel:
    • ((Ha*80)-(R*5))/(80-5)
      • “Ha” refers to the ImageIdentifier of the Ha Channel image.
      • “R” refers to the ImageIdentifier of the Red Channel image.
      • 80 is (I think) the intensity to which to extract the data.
      • 5 refers to the bandpass nm of my Ha filter. In my case, I have a Chroma 36mm Ha 5nm filter.
      • I then renamed the new image as new_Ha
  • I then went to the Red channel image and applied the following formula:
    • $T+(new_Ha-Med(new_Ha))*5
      • “$T” refers to the target image. In this case, is the Red image.
      • “new_Ha” refers to the image created in the previous step.
      • 5, in this case, is the boosting number. This can be higher, depending on how much intensity you want to add into the R channel.
      • In this step, I had PixelMath replace the image.

I then combined the Red, Green & Blue images using LRGB Combination. I did not use the Luminance data in this step. I then performed the following steps in PixInsight:

  • Background Neutralization
  • Photometric Color Calibration
  • EZ Denoise
  • AutoColor
  • Histogram Transformation
  • Extract CIE L* Compoment from RGB image.
  • LRGB Combination (CIE L* Component in L x 4). This step helped boost the saturation in a subtle way and enhanced the blues in the galaxy.
  • Curves Transformation (Using a color mask from the R data)
  • SCNR (Removed Green)
  • Curves Transformation (x2 with range masks and then x2 with the same mask inverted)
  • LRGB Combination
  • Convolution
  • LRGB Combination (Using the Lum data)
  • HDR Multiscale Transformation
  • LRGB Combination (CIE L* Component in L x 2)
  • Curves Transformation (Using a color mask from the B data)
  • NoiseXTerminator (This was my first time using it and I really liked how clean it looked after)
  • Star Mask
  • Morphological Transformation
  • Dark Structure Enhance
  • ICC Profile Transformation

Acquisition Data

Messier 81 and Messier 82Click here for an annotated version of this target.

Processing Info

I took 210 subs, most of them at 300 and a few others at 600 seconds each. I stacked the frames 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 (x3 Using multiple masks created using the GAME script)
    • 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.

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

Acquisition Data

  • Telescope: Explore Scientific FCD100 Series 127mm f/7.5 Carbon Fiber Triplet ED APO Refractor Telescope
  • Camera: ZWO ASI2600MC Pro
  • Guiding: ZWO Off-Axis Guider with Helical Focuser
  • 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-Pro (178 x 300s), Optolong L-eXtreme (17 x 300s, 15 x 600s)
  • Exposure Time: 18 hours 50 minutes -20°C
  • Date: January 21 – 22, March 8 – 9, 2021
  • Location: Voorhees State Park, NJ
  • GPS Coordinates: Lat. 40.68187, Long. -74.89797
  • Temperature: 29°F/-2°C
  • Bortle Dark-Sky Scale: 4
  • Avg. Moon age: 16.78 days
  • Avg. Moon phase: 40.19%
  • RA center: 9h 56′ 14″
  • DEC center: +69° 5′ 35″
  • Orientation: 63.104 degrees
  • Field radius: 1.174 degrees
  • Magnitude: 6.94
  • Resolution: 3720 x 2330