SUNSET: 
0
Photographer:
Jon Greif
Location of Photo:
Alpine, CA, USA
Date/Time of photo:
July 11-12, 2023, between 10 pm and 4 am PDT
Equipment:
Takahashi FSQ-85ED with 1.01x flattener/reducer. ZWO ASI533MC Pro imaging camera. Optolong L-Pro filter. Rainbow Astro RST-135 Mount. ZWO 30mm Mini Guide Scope with ZWO ASI290 Mini guide camera. ASIAIR Plus controller. Processed in Pixinsight 1.8.9. 5 hours integration time.
Description:
M51, better known as the Whirlpool Galaxy, is a favorite Summer target. It is a bright, face-on Spiral Galaxy located near the tip of the handle of the Big Dipper. M51, also known as NGC 5194, is interacting with a smaller companion, NGC 5195, seen connecting to the larger M51 by way of a bridge of stellar material, producing new stars, and, eventually the two will merge. M51 is about 35 percent the size of our own galaxy, the Milky Way, lies 23 million light years away and has an estimated mass of 160 billion solar masses. The Whirlpool Galaxy is one of Charles Messier’s original discoveries. Messier first observed the object on October 13, 1773. The smaller NGC 5195 was discovered by Messier’s friend and colleague Pierre Méchain on March 20, 1781. In his catalogue of 1781, Messier did not make it entirely clear if the object that he was referring to as M51 was just the larger galaxy or the interacting pair. As a result, the Whirlpool Galaxy (NGC 5194) is sometimes referred to as Messier 51a and the smaller NGC 5195 as Messier 51b.
