Imaging M101 The Pinwheel Galaxy using a zenithstar 61ii refractor

 Another session in the back of the garden. You can read about my previous one and some of the limitations I face here: 

https://undersouthwestskies.blogspot.com/2026/03/imaging-session-ngc-2304-intermediate.html

This time I managed to do two nights on the same target and so gather nearly five hours of acquistion time! 

The Pinwheel Galaxy, home of a famous supernova and bright blue arms filled with newborn stars is a spiral galaxy 170,000 lightyears across, located 25 million lightyears away from Earth in the Ursa Major constellation.

The giant spiral disk of stars, dust, and gas is 170,000 light-years across — nearly twice the diameter of our galaxy, the Milky Way and astronomers estimate that M101 contains at least one trillion stars.

The galaxy’s spiral arms are sprinkled with large regions of star-forming nebulas. These nebulas are areas of intense star formation within giant molecular hydrogen clouds. Brilliant, young clusters of hot, blue, newborn stars trace out the spiral arms.

Sadly, I havent quite managed to capture the bluish colour with pink hydrogen cloud rich spots. Hard work is this post editing learning journey! 🤔 I may have mentioned that before! 😆

And for those who like a competition - how many galaxies can you see in the image?



For those wanting to know the acquisition and post editing details:

Equipment:

• Canon 800D astromodded camera paired with zenithstar 61ii refractor and its 61A field flattener.
• Clip in Optolong L-Pro filter.
• Autoguiding uses ASIair Mini with ZWO 120mm mini and RVO 32mm guiderscope.
• The entire rig is powered by a Celestron Lithium Pro power pack and three smaller power banks.
• The mount is a skywatcher EQM-35-PRO.

Data capture details:
Two consecutive nights in back garden under bortle 4 skies. On both nights:

• lights 240" x 40, at ISO 800.
• Calibration frames - 10 dark, 30 bias and 50 flats.

Post editing workflow:
SIRIL:

• crop - autoBGE - veralux NOX - image plate solve - SPCC colour calibration - Aberration remover
• Starnett - veralux hypermetric stretch - veralux curves - veralux revela - veralux star recomposer
• veralux vectra - cosmic clarity denoise and sharpen

Affinity Photo:

• curves and leves - contrast - brightness

If you want to know more about my post editing SIRIL workflow you can find out more here: https://undersouthwestskies.blogspot.com/2025/12/beginner-tutorial-workflow-for-using.html

I couldn't quite capture the bluish tinge to the arms or the pink spots of the hydrogen gas areas - very frustrating. I also think that the images are a little npoisy and so I need to possibly rethink my work flow order. 

As always, feel free to share your images of M101 along with some acquistion details in the comment box below. If you have some processing tips - share them as well. 

As always, clear skies, stay safe out there and keep looking up! 

Steve