Celestial hemisphere:  Northern  ·  Constellation: Ursa Major (UMa)  ·  Contains:  M 101  ·  NGC 5457
M101 Pinwheel Galaxy in HaLRGB, Douglas J Struble
M101 Pinwheel Galaxy in HaLRGB
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M101 Pinwheel Galaxy in HaLRGB

M101 Pinwheel Galaxy in HaLRGB, Douglas J Struble
M101 Pinwheel Galaxy in HaLRGB
Powered byPixInsight

M101 Pinwheel Galaxy in HaLRGB

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Description

This one is a tough one to work on; especially in my heavy light polluted red zone I am in. I started this a couple months ago, however my Astro-Physics Mach1 had to go into warranty repair and was gone for about a month. I finally finished it off after it got back.

M101 is a large face-on spiral galaxy located 22 million light-years away in the constellation of Ursa Major. At magnitude +7.9, it can be glimpsed in binoculars or small telescopes from dark sites. However, this galaxy suffers from low surface brightness and in bad seeing conditions or light polluted areas is sometimes difficult to spot even with 200mm (8-inch) scopes. M101 is best seen from the Northern Hemisphere during the months of March, April and May.

M101 is also known as the Pinwheel galaxy and was discovered by Pierre Méchain on March 27, 1781. He described it as "nebula without star, very obscure and pretty large, 6' to 7' in diameter, between the left hand of Boötes and the tail of the great Bear." He communicated this to Charles Messier, who verified its position and then included it in his catalogue as one of the final entries.

Locating the part of sky where M101 is positioned is easy, since it's close to the handle of the bowl that forms the Plough or Big Dipper asterism of Ursa Major. The Pinwheel galaxy is located at one corner of an equatorial triangle formed with second magnitude stars Mizar (ζ UMa - mag. +2.2) and Alkaid (η UMa - mag. +1.8). M101 is 5.5 degrees east of Mizar (the celebrated naked eye double star) and 5.5 degrees northeast of Alkaid.

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