William Herschel discovered NGC 4503 = H II-66 = h1313 on 15 Mar 1784 (sweep 174) and noted "pB". His descriptions are very brief in this portion of the sweep as he was recording new nebulae rapidly. CH's reduced position is 18 sec of RA too far east. John Herschel made two observations, the first on 11 Apr 1825, his third formal sweep. Dreyer made an observation on 24 Mar 1878, though mistakenly assumed he was observing GC 3077 = NGC 4528. He wrote, "pB, lE N-S, irr figure, fades away more gradually on f[ollowing] side..."

400/500mm - 17.5" (4/25/87): fairly bright, fairly small, elongated ~N-S, very bright core, stellar nucleus.

600/800mm - 24" (5/20/17): bright, fairly large, oval 2:1 or 5:2 N-S, the halo increases to ~2'x0.8' with averted. Sharply concentrated with an extremely bright core that increases to an intense stellar nucleus! IC 3460 lies 6.6' NE,

24" (6/4/16): bright, large, elongated nearly 5:2 N-S, ~1.8'x0.7'. Sharply concentrated with a very large, very bright elonagated core that increases to an even brighter nucleus and stellar peak at the center. The halo gradually fades out but the ratio of major to minor axis is higher in the halo than the core. IC 3470 is 6.7' NE and IC 3483 (the third member of Zwicky's Triplet, along with IC 3481 and 3481A) is 19' NE.

Notes by Steve Gottlieb