Christian Peters discovered NGC 4309 around 1881 with the 13.5-inch refractor at the Hamilton College Observatory in New York. Peters' position matches UGC 7435. The discovery was not published in his two lists in Copernicus 1881 and 1882, so was probably communicated directly to Dreyer.

400/500mm - 17.5" (3/24/90): faint, elongated E-W, diffuse, gradually increases to a small bright core. A mag 13 star is 2.9' E. Located 20' W of the NGC 4343 group.

Notes by Steve Gottlieb