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Summer Beehive Cluster
The Summer Beehive Cluster, officially known as IC 4665, is a large, loose open cluster in the constellation Ophiuchus that shines as a sparkling patch of starlight in early summer skies. Often overlooked, it’s a hidden gem that comes alive in binoculars or a wide-field telescope, rewarding stargazers with a generous sprinkling of young, blue-white stars.

The Summer Beehive Cluster is called this because of its loose resemblance to the Beehive Cluster (Messier 44) in Cancer, which is a well-known open cluster often observed in winter and spring. IC 4665 is not as dense or symmetrical as the Beehive Cluster, but both are bright, relatively nearby, made up of young stars, and best seen in binoculars or wide-field telescopes.

What makes IC 4665 so enticing is how bright and airy it feels. With over 30 stars brighter than magnitude 10, the cluster forms a soft, irregular pattern that seems to float against the Milky Way’s backdrop. Its casual sprawl gives it a natural, relaxed beauty—more like a starry breeze than a tightly packed knot.

Best of all, it’s incredibly easy to find—just north of the bright star Beta Ophiuchi. Whether you’re scanning the sky on a warm summer night or building a binocular tour through Ophiuchus and Serpens, the Summer Beehive is a light-filled pause worth savoring.


Summer Beehive Cluster
Rating: 🔵 Stagazer FavoriteLevel: 🔵 EasyHow: When: Jun - Sep
🌟 Bright and Binocular-Friendly
IC 4665 is one of the few clusters that truly shines in binoculars. Its stars are relatively bright and evenly spaced, making it easy to identify even from semi-dark skies. Its broad size and soft shape give it a natural elegance in low-power views.
🌟 Easy to Find
Just a few degrees north of Beta Ophiuchi, the cluster is easy to locate without detailed star-hopping. This makes it an ideal object for beginners and for quick summer viewing sessions when time or conditions are limited.
🌟 Large and Airy Appearance
Unlike denser open clusters, IC 4665 spans over half a degree with stars that are loosely arranged. This gives it a spacious, breezy feel—perfect for those who enjoy the tranquil charm of the night sky without needing pinpoint detail.
🌟 A Beautiful Warm-Season Target
As its nickname suggests, the Summer Beehive Cluster is well placed for late spring through summer evenings. It offers a bright, pleasant object that’s easy on the eyes and suitable for quick, casual observing.
🌟 Underrated and Overlooked
Because it’s not in the Messier catalog and lies in a relatively sparse region, IC 4665 is often skipped over. But its brightness, accessibility, and charm make it a hidden gem worth revisiting and sharing with others.
🌟 Complements Milky Way Tours
IC 4665 fits beautifully into a wider tour of the summer Milky Way, sitting near clusters, globulars, and planetary nebulae in Ophiuchus and neighboring constellations. It adds variety and contrast to any observing plan.
Summer Beehive Cluster
NamesSummer Beehive Cluster, IC 4665ConstellationOphiuchusDistance1,100 ly
RA, Dec17h 47m 33s, +05° 42' 22"Angular Size70'Magnitude+4.19
Angular
Size
vs
Moon
DSO TypeOpen cluster: a loose group of a few dozen to a few thousand young stars that formed together and are loosely bound by gravity.
Summer Beehive Cluster
Find the Summer Triangle which consists of the three stars, Vega (+0.02), Altair (+0.93) and Deneb (+1.33). In Cygnus, also find Albireo (+3.07).
Hop from Deneb to Albireo and continue to the relatively bright star, Cebalrai (+2.76) in Ophiuchus.
With binoculars or telescope finder, point to Cebalrai. With binoculars or a low-powered eyepiece, hop 1° to the Summer Beehive. The stars aren’t tightly clustered around a central point but instead form an airy arrangement, making it easy to confirm once you’ve landed in the right spot. Explore!
Summer Beehive Cluster
Use Binoculars or Low Power
IC 4665 is large and loosely packed, so binoculars or a telescope with a wide-field, low-power eyepiece will show the cluster best. Higher magnification narrows the view and loses its sweeping charm.
Start at Beta Ophiuchi
To find the cluster, begin at Beta Ophiuchi (Cebalrai), a bright, easy-to-spot star in Ophiuchus. From there, move just a few degrees north—you’ll soon see a soft glow marking the cluster.
Observe Under Dark Skies
While it’s visible in suburban skies, IC 4665 looks best under dark conditions. A darker background brings out the full extent of its stars and helps define its gentle structure.
Let Your Eyes Relax
The cluster doesn’t have a tight core. Scan slowly and allow your eyes to take in the broader field. Its relaxed arrangement of stars is part of its unique appeal.
Summer Beehive Cluster
⚠️ Naked Eye
To the naked eye under dark skies, the Summer Beehive Cluster appears as a faint, hazy glow near Beta Ophiuchi, often mistaken for a small patch of unresolved starlight.
Binoculars
In binoculars, it comes to life as a wide, sparkling arrangement of stars scattered across a generous portion of sky, offering a soft and airy view that highlights its loose structure.
Small Telescope
A small telescope at low magnification reveals more stars and sharper contrast, while preserving the cluster’s open feel.
Medium Telescope
In a medium telescope, the view becomes richer with fainter members emerging, but the cluster may begin to stretch beyond the field of view.
⚠️ Large Telescope
A large telescope adds depth to individual stars but loses the sweeping context, making it harder to appreciate the cluster’s full extent.
Summer Beehive Cluster
The Summer Beehive Cluster is a bright, spacious cluster best appreciated under Bortle 1–4 skies, where its full spread and delicate sparkle are most visible. It remains detectable in light pollution, but its elegance fades as the sky brightens.
🟣 In Bortle 1–2 skies, the Summer Beehive Cluster appears as a soft, glowing patch to the unaided eye, and its stars shine brightly in binoculars with excellent contrast and clarity across a wide field.
🔵 In Bortle 3–4 skies, the cluster remains attractive, with most of its brighter members still visible and the overall shape preserved, though the faintest stars begin to fade slightly.
🟢 In Bortle 5–6 skies, the cluster becomes harder to spot without optics. While still visible through binoculars or a wide-field scope, its outer edges lose definition and fewer stars stand out.
🟠 In Bortle 7+ skies, light pollution washes out the cluster’s subtle glow. Only the brightest stars remain visible in optics, and the cluster’s soft form and charm are largely diminished.