William Herschel discovered NGC 691 = H II-617 on 13 Nov 1786 (sweep 636) and noted "F, cL, vglbM". The NGC position matches UGC 1305 = PGC 6793.

300/350mm - 13.1" (9/29/84): fairly faint, fairly large, almost round, very diffuse, weak concentration. A close double star is off the NE edge. Located 15' SSE of NGC 680 in the NGC 697 group.

400/500mm - 18" (11/22/03): bright, large, slightly elongated E-W, ~2.0'x1.5'. Fairly sharp concentration with a well-defined 45" core surrounded by an unconcentrated halo. A close pair of mag 9-10 stars (uncatalogued) is just off the northeast edge! NGC 691 is the brightest in the NGC 691 group (also called the NGC 697 group and LGG 034) that includes NGC 678, NGC 680, NGC 691, NGC 694, NGC 695, NGC 697, IC 163, IC 167, IC 1730 and others.

Notes by Steve Gottlieb