William Herschel discovered NGC 4145 = H I-169 = h1105 on 18 Mar 1787 (sweep 717) and noted "cB, cL." His position is within the halo on the northwest side. On 28 Apr 1827 (sweep 73), John Herschel reported, "pB; vL; dilute; vglbM."

300/350mm - 13.1" (3/17/86): fairly faint, fairly large, very diffuse, weak broad concentration, slightly elongated E-W. Located 9' W of mag 6.9 SAO 44055, a distraction for the low surface brightness galaxy. NGC 4151 lies 30' S.

600/800mm - 24" (5/30/16): at 200x; fairly bright, very large, roughly oval 4:3 ~E-W, 4'x3', contains a large brighter core and a noticeably patchy or irregular halo with a strong impression of spiral structure. Two arms were fairly confident; one extending east of the core on its south side and another extending west of the core on its north side. Otherwise, it seemed like slightly brighter HII patches in the low surface brightness halo were just resolving in the outer halo. Located 9' due west of mag 6.8 HD 105824.

NGC 4145A = UGC 7175 lies 12' SE. It appeared faint to fairly faint, fairly small as often only the 20" slightly elongated core was visible. Sometimes very low surface brightness extensions E-W were seen, increasing the size to ~35"x20", but the full extension of the arms were not detected.

Notes by Steve Gottlieb