Archive for February 2026

Open Cluster IC 4665 In Ophiuchus: Deep-Sky Wonders

February 5, 2026

From “Deep-Sky Wonders” Walter Scott Houston: selections and commentary by Stephen James O’Meara:   

“Many years ago Glen Chaple, Jr., of Townsend, Massachusetts, “discovered” a deep-sky object in Ophiuchus; he found about two dozen stars forming a group which could be glimpsed with the naked eye.  He likened the cluster to the Praesepe in Cancer, but was not plotted on his copy of “Norton’s Star Atlas.” The object does, however, have a name.  It is IC 4665 and is listed in the “Index Catalogue” to the NGC. In those days of stargazing, serious deep-sky observers soon learned that no single atlas can suit all their needs. Today, of course, IC 4665 is plotted on most modern star charts.” WSH

Now from Sue French “Deep-Sky Wonders” A Tour of the Universe With Sky & Telescope’s Sue French as following:

“The splashy open cluster IC 4665 is barely within the boundary of the Milky Way on the atlas. It’s easy to spot 1.3º north-northest of Beta Ophiuchi, which shares the field of view through binoculars or a finderscope. In my 15×45 image-stabilized binoculars, the cluster’s prominent core spans more sky than the full Moon, and loosely scattered outliers to 70′. Half its 40 stars outline a rough circlet with one star at its center and a stem that leads westward to a slightly wavy line tipped north-northwest. To me, it looks like a simplistic drawing of a flower springing up from a gently undulating patch of the ground. Finish amateur Jaakko Saloranta comes away with a different impression. Through his 80mm refractor, he sees the group as the Fish Spear of Poseidon. ” Sue French

Magnitude: 4.2 Size: 70′

Coordinates: RA 17h 46′ Dec. +05º 43′

The following image from wikisky.org