William Herschel discovered NGC 4242 = H III-725 = h1166 on 10 Apr 1788 (sweep 830) and recorded "eF, cL, bM, iR." JH made two observations and logged (sweep 256), "F; vL; R: vgbM; diam in RA = 15s of time."

300/350mm - 13.1" (4/12/86): very large but very diffuse, 4' diameter, broad weak concentration, large core appears offset to the west, almost round. A mag 11.5 star lies 3.2' E of center and a faint mag 14 star is at the south edge 2.0' from center. Member of the CVn II Group (brightest member M106).

Notes by Steve Gottlieb