When is the best time to observe Caldwell 88?

Caldwell 88 is best observed from April through June, with peak visibility during May when it transits around midnight in the Northern Hemisphere.

Where is Caldwell 88 located in the sky?

Caldwell 88 lies in the constellation Circinus at right ascension 15h 06m and declination -55° 36′.

What telescope do I need to see Caldwell 88?

At magnitude 7.9, Caldwell 88 is easy in 7×50 or 10×50 binoculars.

Caldwell 88 — Open Cluster in Circinus

NGC 5823

Open Cluster Excellent (70/100)

Magnitude 7.9^m OpenCluster Circinus Visible

Credit: Legacy Surveys / D.Lang (Perimeter Institute) & Meli thev. License: CC BY 4.0. (Wikimedia Commons)

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About C88

Description

NGC 5823 is an open cluster in Circinus, about 3,400 light-years away. Also known as the Hidden Treasure Cluster, it contains about 80 stars spread across 10 arcminutes with an age of roughly 700 million years.

Observing Tips

A moderately rich cluster requiring a 4-inch telescope to resolve. Located in the southern Milky Way, the rich star field can make the cluster boundaries difficult to define. Medium magnification works best. Best in winter and spring from southern locations.

History

Discovered by James Dunlop in 1826 from Australia. It lies in the obscure constellation Circinus near the galactic plane.

Fun Facts

NGC 5823 is old enough that its more massive stars have evolved away from the main sequence, and several red giants are visible among the cluster members.

Observe

1Properties

Magnitude 7.9

Angular Size 3.9′

Distance 3,400 ly

Description

Open Cluster [Distance: 3400 ly]

Position & Identifiers

RA 15h 05m 30.7s

Dec -55° 36' 14.4"

Constellation Circinus

Catalog C88

Also known as NGC 5823

Physical size

7.1 light-years across — about 1.6× the Sun-to-Alpha-Centauri distance

2How easy to spot?

Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Easy	Easy	Easy
150 mm Newton 150mm Newt.	Easy	Easy	Easy
Celestron C8 (203 mm SCT) C8 203mm	Easy	Easy	Easy

Easy Medium Hard Very hard Impossible

Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs

Medium on Seestar S50

At 150mm under B5 skies you should resolve about 92 of 462 members.

3Visibility

Set a location in User Settings to see visibility data.

Best season Apr – Jun (peak: May)

4 Eyepiece View

Telescope Eyepiece

125x TFOV: 0.4° Lim. mag: 13.6

C88 · 3.9′ diameter

5 Best Magnification

6Where this cluster sits in time

Open clusters span more than four orders of magnitude in age — from newborn OB associations to ancient, metal-rich survivors.

7 Colour-Magnitude Diagram

A cluster's colour-magnitude diagram reveals its age: the bluer the turn-off point where the main sequence bends into red giants, the younger the cluster.

Loading member data…

Each point is a Gaia-DR3 member. Colour encodes spectral type; size reflects membership probability.