George Johnstone Stoney, LdR's assistant, discovered the numerous knots in M101 during observations made in Apr and May 1851. Samuel Hunter made a remarkly accurate sketch of M101, along with the various knots, in Apr 1861 based on multiple observations. John Herschel estimated the position in the GC based on this sketch.

300/350mm - 13" knot in M101 located just south of the core. Appears as a barely non-stellar spot.

400/500mm - 17.5" (6/7/97): low contrast 25" knot superimposed on the main body of M101 3.0' due south of center. Visibility is hindered as superimposed on the brighter background of the central region.

600/800mm - 24" (5/24/20): at 225x and 375x; faint, small, round, 20" diameter. One of the lowest surface brightness HII knots in M101 that has a NGC designation. Located 3' due south of center.

Notes by Steve Gottlieb