William Herschel discovered NGC 5170 = H V-22 = h1610 on 7 Feb 1785 (sweep 369) and recorded "mE from sf to np; 5 or 6' long, the following part is the brightest. His position matches this large edge-on. A second observation on 7 May 1787 (sweep 732) reads "pB, mE, the preceding part much brighter than the south following, about 4' long." JH made two observations, noting on sweep 354 "F; vmE in pos 128.8° by micrometer; pgbM; 180" l, 30" br."

400/500mm - 17.5" (5/19/01): fairly faint but large, very thin edge-on NW-SE. On first glance appeared 4'-5' in length at 220x but with averted vision this impressive ray extends to at least 6'x0.7'. Contains a moderately bright and slightly bulging oval core 1.2'x0.7' giving the galaxy a classic thin "lens" appearance. The extensions are significantly fainter and taper and dim towards the tips. This galaxy has a narrow dust lane (not seen) similar to NGC 4565. A mag 9.5 star lies 9' SW.

Notes by Steve Gottlieb