Heinrich d'Arrest discovered NGC 609 on 9 Aug 1863 (one of two open clusters he found, along with NGC 133) with the 11-inch refractor at Copenhagen. He noted it as "subtle and elegant group of stars mag 14-15; 4' dia; nearly round." His single RA measure is ~50 seconds too large and this error was carried over into the NGC, RNGC and Sky Catalogue 2000.

200/250mm - 8" (1/1/84): not found.

300/350mm - 13.1" (12/7/85): faint, fairly small, diffuse, about six very faint stars over unresolved haze. Located 10' SSW of mag 6.6 SAO 11875.

600/800mm - 24" (1/4/14): at 200x, ~15 faint to very faint stars sparkle over an unresolved background glow ~2.5' diameter. Two brighter mag 12/13 stars are detached, just off the southwest end. The cluster is 2.5' NW of MLB 187, a 5" pair of mag 9/9.5 stars.

Notes by Steve Gottlieb