Heinrich d'Arrest discovered NGC 4858, along with NGC 4860, on 21 Apr 1865 with the 11-inch refractor at Copenhagen. He described these as a double nebula. NGC 4858 is the faintest of the 34 members in the Coma cluster that d'Arrest discovered. Based on my own observations with 17.5" and 18" scopes, in which I called it "very faint" and "extremely faint", I'm impressed that d'Arrest noticed it through the 11-inch Fraunhofer, though there are other similar examples!

400/500mm - 17.5" (4/21/90): extremely faint and small, round, requires averted. Forms a very close pair with NGC 4860 34" NE. Member of AGC 1656.

Notes by Steve Gottlieb