William Herschel discovered NGC 521 = H II-461 = h115 on 8 Oct 1785 (sweep 462) and recorded "F, pL, irr R, bM." On 20 Dec 1786 (sweep 655) he noted "vF, R, vgbM, 1 1/2' diam." JH made two observations, calling it "B" and "vF" on the two sweeps. R.J. Mitchell, using Lord Rosse's 72" on 3 Oct 1856, logged "pB, S, disc enveloped in F outlying neby and looks like an unresolved cluster." The NGC position is accurate.

300/350mm - 13.1" (1/1/84): sharply concentrated with a very small bright core surrounded by a fairly large but very diffuse round envelope. Located 14' W of NGC 533.

600/800mm - 24" (9/23/17): at 375x; bright, large, round, at least 2' diameter, sharply concentrated with a large bright core that gradually increases to the center (quasi-stellar nucleus), halo fades out at the periphery. NGC 533 lies 14' ENE.

Notes by Steve Gottlieb