William Herschel discovered NGC 5157 = H III-651 = h1606 on 20 Mar 1787 (sweep 722) and noted "vF, S." JH made three observations and logged (sweep 337) "Not vF; pL; E; the following of 2 [with NGC 5166], very similar." His mean position matches UGC 8455.

400/500mm - 17.5" (5/15/99): fairly faint, moderately large, slightly elongated, 1.2'x1.0'. Broad, weak concentration with a slightly brighter core. NGC 5166 is 12' following.

Notes by Steve Gottlieb