🌌 #20: M81 and M82

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February 16, 2019 – M81/M82 – 1h 29min total | 50s subs @ ISO 400 | +1°C

🧭 Two Galaxies, One Frame

This session was about something new: capturing two galaxies in a single shot. I’d spotted M81 and M82 in Stellarium the night before and realized they would both fit perfectly in the frame of my Olympus E-510 paired with the SkyWatcher 150/750 Newtonian.

That was the easy part.

🎯 The Art (and Agony) of Framing

Framing the shot turned into a comedy of errors. I used ISO 1600 and 60-second test exposures to help locate the pair — but my EQ-3 Pro mount, with its high slewing error and imperfect alignment, made the hunt painfully slow.

My sister and her fiancĂ© watched the whole drama unfold. I’d move the scope ever so slightly

📾 Take a test shot

Wait
 60 seconds

🧐 Nope, wrong way.
Reslew. Test shot. Still off. Where did the galaxies go?
Reslew again
 and again


It took me nearly an hour just to properly frame the two galaxies in one shot. But once I had them both centered, I locked in 50-second subs (longer exposures resulted in star trailing due to poor alignment), and let the session run for nearly 90 minutes.

I ended up with:

  • 1h 29min of light frames
  • 20 darks
  • 20 bias frames
  • And even 20 flats, taken the next morning

That alone felt like a win.

đŸ§Ș Image Processing

Straight out of the stack, I ran into a major issue: a strange gradient across the image. After troubleshooting a bit, I removed the flat frames — and suddenly, the gradient mostly disappeared. The flats looked fine individually, so the cause still remains a bit of a mystery.

With the stacked image cleaned up, I:

  • Cropped the edges to remove stacking artifacts
  • Aligned the black and white points using histograms (still my go-to method at the time)
  • Applied layer masks to stretch the galaxies without blowing out the background
  • Focused on pulling out M81’s spiral arms and the inner structure of M82

Unfortunately, the faint red dust jets of M82 — those iconic features — barely showed up in my data. I’d seen them in other images and always found them captivating. But at 50s per frame on ISO 400
 it’s clear I need more exposure time (and darker skies).

đŸ–Œïž Three Versions

  1. High-contrast version – Best structure in the galaxies, but I pushed the black level too far and lost faint detail.
  2. Smartphone-optimized version – Slightly overexposed to make it pop on small screens. Bright, but noisier.
  3. Natural-look version – Tried to balance realism with smoothness, but this one introduced odd star colors and left some gradient visible

Despite the quirks, I’m really happy I found and framed both galaxies — and produced a usable image on my first try.

🧠 Conclusion

Framing is hard.
It takes time, patience, and a good sense of direction (or a lot of trial and error). Combine that with a wobbly mount and imperfect polar alignment, and you’ve got a challenge on your hands.

But this session also sparked a realization:
It’s time to take the next step and look into guiding.
With a guidecam and PHD2, I could:

  • Plate solve for precise framing
  • Properly polar align
  • And most importantly: guide my mount, which means longer exposures, better signal, and cleaner stars

It feels like the natural next upgrade in this ever-growing journey.

Clear skies,
Chris