Messier 101: A Stunning Glimpse of the Pinwheel Galaxy

This past July 18th, under a Bortle Class 6/7 sky, I turned my gaze towards one of the most iconic celestial objects: Messier 101, also known as the Pinwheel Galaxy. This grand design spiral galaxy, located approximately 21 million light-years away in the constellation Ursa Major, is a favorite among astronomers and astrophotographers alike for its intricate spiral arms and prominent structure.

Capturing the Cosmos: The Technical Details

Bringing the Pinwheel Galaxy into sharp focus requires a combination of good equipment and patience. Here’s a breakdown of the setup and workflow that went into creating this image:

• Mount: Sky Watcher EQ-AL 55i pro
• Camera: Nikon D3500 (Stock)
• OTA (Optical Tube Assembly): Nikkor 70-300 mm f 4.5
• Focal Length: 300mm
• Aperture: f/6.3
• ISO: 800
• Exposure Time: 60 seconds per frame
• Total Integration Time: 1 hour 15 minutes

The Data Pipeline

• Lights: 77 frames
• Darks: 20 frames
• Bias: 27 frames
• Flats: 27 frames

Bringing the Image to Life: Post-Processing

Raw astronomical data is just the beginning. The magic truly happens during post-processing, where various software tools are employed to stack, enhance, and refine the image. The workflow for this shot involved:

1. DeepSkyStacker: Used for stacking the light, dark, bias, and flat frames. This crucial step reduces noise and brings out fainter details by averaging multiple exposures.
2. Starnet++: Applied to remove stars, allowing for focused processing of the galaxy’s structure.
3. Siril: A powerful open-source software for astronomical image processing, used for initial stretch, background neutralization, and color calibration.
4. Graxpert: Employed for noise reduction and further enhancement of the galactic details.
5. GIMP: The final stage for fine-tuning, color balancing, and overall composition to present the Pinwheel Galaxy in all its glory.

The Result

After hours of careful acquisition and meticulous processing, the result is this breathtaking view of Messier 101. The distinct spiral arms, punctuated by bright star-forming regions, are clearly visible, offering a glimpse into the dynamic nature of this distant galaxy.

This project was a rewarding experience, pushing the limits of my equipment and processing skills. I hope you enjoy this journey through the cosmos!