IC 4765 is the brightest cD galaxy in the rich cluster ACO S805 = Pavo II Cluster, which includes IC 4766, IC 4767, IC 4770, IC 4771. A total of 7 galaxies lie within 5' of IC 4765 and 13 galaxies were noted within 10'! IC 4766: moderately bright, fairly small, elongated 5:3 WNW-ESE, 45"x27". This member of the IC 4765 cluster is situated 1.6" ENE of a mag 12 star and 3.2' NE of IC 4765. IC 4767: moderately bright and large, elongated 3:1 SSW-NNE, 1.2'x0.4', bright core. A star is at the north-northeast tip. Located 5.2' SSE of IC 4765 in the core of the cluster.

IC 4769: fairly bright, moderately large, elongated 2:1 NW-SE, 1.0'x0.5', gradually increases to the center, but no distinct core or zones. Located 11' NNE of IC 4765 and second largest in the cluster. IC 4770: very faint, small, round, 20" diameter, fairly low surface brightness. A mag 14.5 star is involved on the west end and interferes with viewing. Located 6.5' SE of IC 4765 in the cluster. IC 4771: fairly faint, fairly small, slightly elongated N-S, 1.2'x0.4', even surface brightness. Located 4.7' WNW of mag 7.4 HD 173344 and 9' NE of IC 4765 in the ACO S805 cluster.

ESO 104-002: fairly faint, fairly small, slightly elongated, 20"x15", slightly brighter core. This member of the IC 4765 cluster is located 3.3' SW of IC 4765 in the core of the cluster. A mag 14.8 star lies 35" S.

ESO 104-007: moderately to fairly bright, fairly small, slightly elongated E-W, 25"x20". This member of the IC 4765 cluster is situated 33" NE of a mag 10.3 star and 1.7' S of IC 4765.

ESO 104-008: faint to fairly faint, contains a small, round 18" core and very dim extensions NNW-SSE increasing the size to 0.5'x0.3'. This member of the IC 4765 cluster is situated 50" SSE of a mag 12 star and 1.4' NNE of IC 4765.

ESO 104-012: fairly faint, fairly small, elongated 2:1 N-S, 0.5''x0.25', irregular shape, even surface brightness. Located 2.8' SE of IC 4769 and 10' NE of IC 4765.

PGC 62384: very faint, small, round, 15" diameter. Located 3.1' WNW of IC 4765.

PGC 62391: fairly faint, fairly small, round, 0.5' diameter. Located 3.1' WNW of IC 4765.

DeLisle Stewart discovered IC 4765 = D.S. 516, along with a number of other IC's, on a plate taken on 20 Jul 1901 at Harvard's Arequipa Station in Peru. He noted "vF, S, R, bM."

600/800mm - 30" (10/12/15 - OzSky): at 303x; bright, fairly large, elongated 5:2 WNW-ESE, ~100"x40", sharply concentrated with a very bright core that increases to a stellar nucleus.

Notes by Steve Gottlieb