M101 = NGC5457 ( 14h 03.2m +54°21´, 7.7 mag. )
This large "grand design-type" face-on spiral galaxy in Ursa Major was discovered by Mechain in 1781. Messier observed it on March 27, 1781. Like M33 and M99, it is sometimes named Pinwheel Galaxy. Its arms are defined by bright associations of young stars and numerous HII star forming regions (some of those are cataloged as separate NGC objects). M101 is located about 17.5 million ly away and measures 90,000 ly across. To find it follow a chain of four magnitude 8 stars for about 5°40' E of Alcor-Mizar pair (z Ursae Majoris and 80 Ursae Majoris - see finder chart below). M101 is noticable in binoculars.
The above image was taken on April 10, 1999 from Sooke, BC. Cookbook 245 LDC CCD camera was used on Celestron Ultima 8 f3.0 telescope autoguided with Cookbook 211 LDC CCD camera on piggybacked 500mm f8 telephoto lens. Seven white exposures (240 sec. each) were combined with three cyan, four magenta and four yellow-filtered integrations (240 sec. each) using AIP4WIN software. Color image was then adjusted with Corel PhotoPaint 8 in Lab color space.
North is to the right.
Map created in Guide 7.0 - 7°45' x 10°. North is up.
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© Jan Wisniewski