Fun facts
M101 Pinwheel Galaxy (also known as Messier 101, M101 or NGC 5457) is a face-on spiral galaxy 21 million light-years (6.4 megaparsecs) away from Earth in the constellation Ursa Major. It was discovered by Pierre Méchain in 1781 and was communicated that year to Charles Messier, who verified its position for inclusion in the Messier Catalogue as one of its final entries.
M101 is a large galaxy, with a diameter of 170,000 light-years. By comparison, the Milky Way has a diameter of between 100,000 and 120,000 light-years. It has around a trillion stars. It has a disk mass on the order of 100 billion solar masses, along with a small central bulge of about 3 billion solar masses. It is estimated that M101 has about 150 globular clusters, the same as the number of the Milky Way’s globular clusters. Its characteristics can be compared to those of Andromeda Galaxy.
M101 is asymmetrical due to the tidal forces from interactions with its companion galaxies. These gravitational interactions compress interstellar hydrogen gas, which then triggers strong star formation activity in M101’s spiral arms that can be detected in ultraviolet images.
Other Catalog Designations: M101, NGC 5457
Subtype: Spiral Galaxy
Distance from Earth: 21 million light years
Size: 170,000 light years
Constellation: Ursa Major
{From: https://en.wikipedia.org/wiki/Pinwheel_Galaxy}
Capture Notes
Imaging on both 19 and 20 February was with the “old” HP Probook (DSO CTRL 1), Big Zeus, ASI2400MC, and the LPro light pollution filter. On 19Feb2023, M101 Pinwheel was the second target of the night, after NGC2359 Thor’s Helmet set. On 20Feb2023, M101 Pinwheel was the second target of the night, after NGC2170 Monkey Head set.
This image is all the data collected on 19 February and 20 February 2023.
Equipment
Polar alignment: QHYCCD camera (controlled by Polemaster)
Imaging stream: Orion 10″ f/8 Ritchey-Chretien Astrograph Telescope, ZWO ASI2400MC imaging camera with Optolong L-Pro LP filter.
Mount: Sky-Watcher EQ6-R Pro Equatorial Mount (controlled by EQMOD)
Autoguider: Orion 60mm Multi-Use Guide Scope, Orion StarShoot AutoGuider Pro Mono Astrophotography Camera (controlled by PHD2)
Equipment controlled by HP Probook (DSO CTRL 1) running Sequence Generator Pro v3.2.0.660.
Capture & processing notes
Sequence plan:
Night 1: 19Feb2023: Gain: 158, Temp: -0°C, no offset. BZLPro 39x5min; Captured 20Feb2023, 0026MST – 0349MST. Total exposure time: 3:15hrs.
Night 2: 20Feb2023: Gain: 158, Temp: -0°C, no offset. BZLPro 30x5min. Captured 21Feb2023, 0116MST – 0351MST. Total exposure time: 2:30hrs.
Multi-session stack: 69x5min; Total exposure time: 5:45hrs
Capture: 19 & 20 February 2023
Shooting location: Colorado Springs, Colorado
Processing: Stacked in APP, processed in LR/PS.