Spring has broken and we finally got a short run of good clear nights here in central Oregon. I'm breaking in a lot of new gear with this image so I wasted quite a lot of the clear sky time just working out bugs and getting everything working. During this period I only got short periods of no wind, which permitted short periods of superb stability. Most of the time it was blowing 4-6 kts with pretty mediocre seeing. FWHM in the L channel peaked at around 1.7 arc-sec but was mostly in the 2.0-2.3 arc-sec range. On top of that, this is my first CCD (LRGB+Ha) image so I'm struggling a little to figure out the processing flow. With a little more practice, I think that I might be able to get better at it; but, this isn't a bad start. It is especially nice to be able to see the Ha regions standing out in the spiral arms. As always, C&C is welcome and appreciated.

A Bit about M101:

M101, the Pinwheel Galaxy is a large face-on spiral galaxy 21 million light-years away in the constellation Ursa Major. It was discovered by Pierre Méchain on March 27, 1781. Charles Messier verified its position and included it in the Messier Catalogue as one of its final entries. M101 is comparable in size to the Milky Way with a diameter of 170,000 light-years. It has a mass on the order of 100 billion solar masses residing in the disk and a small central bulge of about 3 billion solar masses.

This image shows the high number of H II regions visible in M101. H II regions usually accompany the enormous clouds of high-density molecular hydrogen gas contracting under their own gravitational force where stars form. H II regions are ionized by numerous extremely bright and hot young stars; those in M101 are capable of creating hot superbubbles. In a 1990 study, 1,264 H II regions were cataloged in the galaxy. Three are bright enough to receive NGC numbers - NGC 5461, NGC 5462, and NGC 5471.

The overall structure of M101 is influenced by the tidal forces from interactions with its companion galaxies. That's what gives the arms such an asymmetric appearance. These gravitational interactions concentrate interstellar hydrogen gas, which triggers star formation activity in M101's spiral arms.

John

PS My first version included too much noise from the Ha channel and it was a bit "over-cooked." I've toned it down a bit and cleaned up a lot of the Ha noise in the latest version. It may take a while before I get the full LRGB+Ha process nailed down!