My first run of the night ended unexpectedly. Not sure what happened but it seems my computer decided it was a good time to restart or update or something. So on to another target in the neighborhood. The Pinwheel Galaxy or M101 is front and center. Low to the right is NGC 5474.

Per Wikipedia:

NGC 5474 is a peculiar dwarf galaxy  in the  constellation Ursa Major . It is one of several companion galaxies of the Pinwheel Galaxy (M101 , a grand-design spiral galaxy . Among the Pinwheel Galaxy’s companions, this galaxy is the closest to the Pinwheel Galaxy itself. The gravitational interaction between NGC 5474 and the Pinwheel Galaxy has strongly distorted the former. As a result, the disk  is offset relative to the  nucleus ] The star formation in this galaxy (as traced by  hydrogen  spectral line  emission) is also offset from the nucleus.  NGC 5474 shows some signs of a spiral structure. As a result, this galaxy is often classified as a dwarf spiral galaxy , a relatively rare group of dwarf galaxies.

I was also running dithering for the first time on an actual imaging run. This is a concept where the scope moves a bit between each sub, or individual photo. Some people swear by this as a great way to improve results, and as I did this time, avoid taking dark shots. “Darks” take the same time as “Lights” and are super boring time hogs looking at the black interior of the telescope cover. The idea of darks is to subtract the noise. The idea of dithering is to randomize the noise and thus it keeps reducing the more individual subs are compiled together, or “Stacked”. Stacking is fundamental to modern astrophotography and the whole digital revolutionary leap that makes all this amateur stuff so much fun!

In this photo:

• NGC 5486
• NGC 5485
• NGC 5477
• NGC 5474
• NGC 5473
• M 101
• NGC 5457

M101, Pinwheel Galaxy
Annotated Pinwheel Galaxy courtesy

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