William Herschel discovered NGC 4605 = H I-254 = h1381 on 19 Mar 1790 (sweep 953) and recorded "eB, E, about 5' long in the parallel, all over equally bright, except just on the edges." JH made a single observation (sweep 344): "B; L; vmE; in pos 118.6°; glbM; 4' l and 1' br."

200/250mm - 8" bright, moderately large, very elongated NW-SE.

400/500mm - 18" (5/14/07): very bright, large, nearly edge-on 3:1 NW-SE. The relatively large, bulging core is mottled. The southeast extension is brighter, mottled (HII regions) and tapers towards the tip. The very tip of this extension appears to hook slightly towards the east. The fainter northwest extension is much more diffuse, is broader and fades at the ends. The major axis of the two extensions are slightly skewed with respect to each other as if they were bent at the center or possibly the brighter southeast extension is warped or distorted.

18" (5/8/04): very bright, large, quite elongated 5:2 ~NW-SE. Contains a relatively large, high surface brightness elongated core. This galaxy's structure is very unusual with careful viewing. The southeast extension is clearly brighter and more tapered than the northwest end. The surface brightness of the southeast extension is noticeably uneven with a mottled or splotchy appearance possibly from HII regions and an irregular distribution of dust. Near the center there is a slight bend or kink to the major axis, with the fainter northwest extension slightly misaligned. Also the northwest extension appears to fan out somewhat at the northwest edge and fade into the background.

Notes by Steve Gottlieb