Saturday night I managed a quick look at M51 with the same scope from the same site. At 300x with a ZAOII-6, two of the brightest and largest HII regions were visible. They were cataloged by Carranza, Crillon, and Monnet in a 1969 Astronomy and Astrophysics paper (1:479) as #71 and 72. I refer to this catalog as "CCM".

On the photographic chart in Stoyan's Atlas of the Messier Objects they (or their starlike cores) are labeled L 203 and L 180. I was unable to determine the origin of these "L" designations or what type of objects they represent.

CCM 71 was labeled as such on Howard's sketch in his July 2011 S&T article. Based on location, I am certain that the much more compact object to its NW in Howard's sketch is CCM 72, although the difference in size between it and CCM 71 in his sketch is greater than in my view.

At 225x I saw the starlike center in 71 flickering in the center of a compact nebulosity that has a weak narrow extension terminating around the position of CCM 72. At 300x, the two objects were fully resolved and looked similar in brightness and size, 72 still being more prominent and each exhibiting a starlike center surrounded by compact, strongly concentrated nebulosity.

16", Cherry Springs, good seeing, poor transparency, 50% humidity, 12C, 200-300x, north up, west right
2013-04-27 M51 labeled.jpg