Christian Peters discovered NGC 4604 around 1881 with the 13.5-inch refractor at Hamilton College Observatory. The discovery was not published in either of his two Copernicus lists in 1881 and 1882, so the discovery must have been communicated directly to Dreyer, though there is no description in the NGC. The NGC position is 2' southeast of the center of NGC 4602.

The 1921 Helwan Observatory publication reported that NGC 4604 was not found on an 80 min exposure taken between 1914-16 with the 30" reflector. Dorothy Carlson mentioned this in her NGC errata list and RNGC classified the number as nonexistent. RC3 and SEGC identify MCG -01-32-037 = PGC 42489 as NGC 4604. This galaxy is nearly 10' south of the NGC position. This identification is possible assuming Peters made a single digit error in declination but considering the close match in position it is more likely that NGC 4604 is a duplicate observation of NGC 4602. Harold Corwin leaves the identification NGC 4604 = PGC 42489 stand, but Courtney Seligman strongly argues that NGC 4604 = NGC 4602.

400/500mm - 17.5" (1/31/87): faint, fairly small, edge-on WNW-ESE. Third of four in the field and located 11' SSE of NGC 4602.

Notes by Steve Gottlieb