Object: M101, NGC5457
Type: Spiral galaxy, type Sc
Constellation: Ursa Major (UMa)
Location: RA: 14h 03m 13s DEC: +54°21'03" (E 2000)
Brightness: 7,9m
Size: 28,6' x 26,5'

M101 was discovered by P. Mechain in 1781. It a beautiful example of spiral galaxy with central bulge laying in different location than center of the spiral arms. It was even classified as "untypical" galaxy by Arp. Despite it's brightness. it is a difficult object due to low surface brightness. As the spiral structure is not visible in small telescopes, brighter parts of the spiral arms got their own NGC designations (NGC 5449, 5450, 5451, 5453, 5455, 5458, 5461, 5462). Estimated distance of 24 million light years. At this distance, M101 has a diameter of 170.000 light years and brightness 30 billion times greater than the Sun. It may be one of the biggest spiral galaxies. 3 supernovae was discovered in M101 - in 1909, 1951 and in 1970. The M101 itself is a center of a small group containing at least 9 other members, including NGC 5474 and 5485.