IC 4665

Open Cluster IC 4665

(= De Cheseaux No. 2)

in Ophiuchus

Right Ascension	17 : 46.3 (h:m)
Declination	+05 : 43 (deg:m)
Distance	1.4 (kly)
Visual Brightness	4.2 (mag)
Apparent Dimension	70 (arc min)

IC 4665 is a very conspicuous, coarse star cluster in the opera glas, but

difficult to detect in the telescope so that neither Messier nor one of the

Herschels found it. The Sky Catalogue 2000.0 gives 30 member stars, the

brightest of which is of 6.86 magnitude, a Trumpler type of III 2 p, and

an estimated age of 36 million years. At a distance of 1,400 light years,

IC 4665 is approaching us at 12 km/sec.

IC 4665 has been discovered by the Swiss astronomer

Philippe Loys de Cheseaux, according to the

Webb Society Deep-Sky Observer’s Handbook, Volume 3 (Open and Globular

Star Clusters), p. 3.

In John Caldwell’s Best Sky Objects list.

In the

Astronomical League’s Deep Sky Binocular Club List.

---

Hartmut Frommert

([email protected])

Christine Kronberg

([email protected])

Last Modification: 8 Mar 1998, 19:30 MET