William Herschel discovered NGC 3593 = H I-29 = h840 on 12 Apr 1784 (sweep 188) and recorded "B, cL, lE, mbM, r." John Herschel made 4 observations, the first on 10 Apr 1825 (sweep 2), while still developing his technique. On 13 Mar 1826 (sweep 22) he noted, "B; E; psmbM; 40" l, 30" br."

R.J. Mitchell, observing on 27 Mar 1856 with the 72", logged "suspect as before a dark lane along the n side of the nucleus and neby outside this again, but far from being certain."

400/500mm - 17.5" (4/1/95): bright, fairly large, very elongated 3:1 E-W, 3.2'x1.2'. Strong concentration from a faint outer halo to a prominent elongated core and a very small rounder nucleus.

Notes by Steve Gottlieb