How to photograph the Pinwheel Galaxy (M101)
A big, face-on spiral just above the handle of the Big Dipper.
Photo byESA & NASA(CC BY 4.0)
When to shoot it from your location
About the Pinwheel Galaxy
M101 is large and faint, with loose spiral arms full of pink star-forming knots. Long total exposure under dark skies matters more than focal length for this one.
Gear and framing
The Pinwheel Galaxy spans about 29′ of sky. It frames best with:
- Small refractor (250-600mm)
- Long focal length (800mm and up)
You can see how other people have built their rigs on RigDesigner, including my Sony a6700 and 60mm refractor rig.
Filters
This is a broadband target, which means its light is mostly starlight across the whole spectrum. Shoot it with no filter or a UV/IR cut filter. A broadband light pollution filter can help a little in the suburbs. Dual-band and narrowband filters block most of its light, so leave them off. Plan it for a moonless night at a dark site.
Tips
- It has low surface brightness, so wait for a moonless night and a dark site.
- Three or more hours of integration brings out the faint outer arms.
Processing
Stack your light frames with darks and flats, then remove the background gradient before stretching. AstroBake does all of this for you. Point it at your folders of raw frames, then adjust the result with live sliders.