NGC/IC Project Restoration Effort

===== NGC 5194 is the Whirlpool Galaxy, one of the nearest and most spectacular of the giant spirals. It has the distinction of being one of the first to be recognized as a spiral by Lord Rosse with his 72-inch reflector. It is also the first of two galaxies comprising Messier 51; the second is NGC 5195. Unlike M 76 (= NGC 650/651), Messier noticed that this object was in fact a pair. The two galaxies are interacting -- with interesting results for both. N5194's "grand-design" spiral pattern probably owes its existence to N5195, while N5195 itself has dust lanes from the outer arm of N5194 superposed on its generally amorphous structure. Plumes and an irregular corona around N5195 are also the result of the interaction. Finally, the two galaxies may be in the process of merging. Some billions of years hence, observers may well see only a single, giant elliptical galaxy where we currently have a pair of the most magnificent extragalactic objects in the sky.

===== NGC 5194 48" (5/12/12 and 4/7/13): during these views with Lowrey's 48" I focused on some of the brighter knots in the spiral arms, which have a very high contrast with the large, dusty, darker regions between the arms. The "southern" arm nearly merges with the core on the northeast side. As this arm unwinds clockwise to the west, two close very small, fairly bright knots ([CCM69] #77 in Carranza, Crilon and Monnet's "Kinematic Study of Ionized Hydrogen in M51" in A&A, 1, 479) are visible 1.6' W of center, just SE of a star. A small bright knot (#71) is further out on this arm, 2.3' SW of center. The section of the arm between these knots is quite bright and mottled. The southern arm then continues to swing around on the east side and heads north, with a lower surface brightness bridge to NGC 5195. The "northern" arm begins on the south or southwest side of the core, and a series of small knots (#60/67) are along the inner south side, roughly 1' from center. As the arm unwinds on the east side of the core, a large bright knot (#52) resides ~1.4' ESE of center. The arm is quite bright in a large, clumpy region (#27/29) as it heads north in the direction of NGC 5195. At the closest point to NGC 5195 are 4 very small knots; the brightest is #10, 2.6' NNE of center. Very close southwest is #8 and just northwest is #5. This arm then has a sharp bend and shoots west on the north side and includes a moderately large, brighter patch (#90/91) 2' NNW of center. The arm fades somewhat as it unwinds further along the western edge of the halo. 48" (4/2/11): during this observation I focused on the attached companion NGC 5195. The entire connecting arm was always a prominent direct vision feature of the pair with variations in brightness and width along its length. The arm brightened as it connected to NGC 5195. The slightly oval core was extremely bright but nevertheless a very bright stellar nucleus punctuated the center. The spiral arms had an extremely high contrast and appeared etched in the eyepiece like a photograph with a great deal of knotty structure. The outer arm that sweeps clockwise to the north and then around the west side extended much further south (~5' from center) than I had ever previously seen and separated quite a bit from the main spiral. Sprays of nebulosity looped off of NGC 5195 to the north (see notes). 18" (7/2/11): first view of type IIb supernova 2011dh in M51, which was discovered after the last time I could observe. The magnitude was ~13.3. The progenitor star of SN 2011dh is possibly an extremely unusual yellow supergiant with a massive blue companion that was leeching material off the yellow supergiant. 17.5" (3/28/87): stunning spiral structure, connecting arm visible with direct vision. First observation with 17.5" on 23 Mar 1985. 13.1" (4/24/82): very bright, very large, bright nucleus. Two winding spiral arms are obvious with a dark gap between the arms on the west side. The connecting arm to NGC 5195 is definite although near my visual threshold. There is a sharp bend in the outer arm at the south end of the galaxy. After this point, the arm trails faintly north to NGC 5195 located 4.6' from center. 8": bright, large, hint of spiral arms.