M 101 – The Pinwheel Galaxy


The Pinwheel Galaxy is much larger than our Milky Way galaxy and its distance is estimated at 22 million light years. The fact that it is seen face-on gives it a low surface brightness. It is therefore not easy to observe visually. It is located in the constellation Ursa Major, therefore it is visible a good part of the year.

M 101 hosts a large number of open clusters, globular clusters and large regions of molecular hydrogen. Under the effect of their own gravity, these clouds contract and give birth to stars. These regions can be photographed and highlighted with an H-Alpha filter. We see them as shiny spots in the outer spiral arms in this photo.

Technical details:

Telescope: SkyWatcher Esprit 120mm f/7 APO
Mount: Paramount MX+
Camera: ZWO ASI 1600MM
Filters: ZWO LRGB and H-Alpha
Exposure: 56 x 3 minutes in LRGB and 8 x 20 minutes in H-Alpha
Place: Backyard observatory in Sainte-Sophie, Qc
Date: July 2017