John Herschel discovered NGC 6404 = h4020 on 27 Jun 1837 and recorded "a p rich, L, F, cluster; class VII; nearly fills field; composed of concave flakes; no m comp; stars 13 or 15m." The observation was included in a list of "omitted observations of nebulae and supplementary nebulae" at the end of the Cape Catalogue. Dreyer identified these objects as "h o n" ([John] Herschel Omitted Object) in the NGC. His position is accurate.

300/350mm - 13.1" (7/5/83): 20 stars mag 12-14 over unresolved haze. The three brightest stars form a small triangle on the west edge, most other stars are very faint. Located one degree south of M6.

Notes by Steve Gottlieb