Deep Sky
M51

NGC5194
Whirlpool Galaxy

With the recent SN 2005cs derived estimate of 23 Mly distance, and an angular diameter of roughly 11.2′, meaning that M51's bright circular disk has a radius of about ~38,000 light-years. Its mass is estimated to be 160 billion solar masses.  Image taken: May 20, 2010
40- 20 sec images stacked