Heinrich d'Arrest discovered NGC 7617 = m 572 on 23 Sep 1864 with the 11-inch refractor at Copenhagen. He noted it preceded NGC 7619 by 6.5 seconds of time and 2' to 2 1/2' south. Albert Marth independently discovered NGC 7617 just two months later on 25 Nov 1864 while observing the cluster. Both are credited in the NGC (d'Arrest is listed first).

But Bindon Stoney probably made the original discovery on 30 Aug 1851 at Birr Castle, noting "I suspect 2 small nebula p[receding] h2330 NGC 7619], though perhaps they are stars." A sketch in the 1880 publication shows NGC 7617 at the correct orientation with a separation of 4'. Because of his uncertainty, Stoney didn't receive credit in the NGC.

300/350mm - 13.1" (9/22/84): faint, very small, round. Easy with averted.

13.1" (11/5/83): very faint, very small, round.

400/500mm - 17.5" (9/14/85): faint, small, slightly elongated oval, brighter core. Forms a pair with much brighter NGC 7619 2.8' NNE in the Pegasus I cluster.

Notes by Steve Gottlieb