William Herschel discovered NGC 4688 = H III-543 = h1429 on 17 Apr 1786 (sweep 553) and noted "eF, pL." JH measured a fairly accurate position and noted "10 sec following a * 9-10 mag." A bright knot on the northwest end appears bright enough to be a visual object.

400/500mm - 17.5" (4/21/90): extremely faint, fairly large, round, very low surface brightness, brighter core. Appears as a hazy region without distinct borders. Located 3.8' E of a mag 10.5 star.

Notes by Steve Gottlieb