When is the best time to observe Caldwell 97?

Caldwell 97 is best observed from February through April, with peak visibility during March when it transits around midnight in the Northern Hemisphere.

Where is Caldwell 97 located in the sky?

Caldwell 97 lies in the constellation Centaurus at right ascension 11h 37m and declination -61° 37′.

What telescope do I need to see Caldwell 97?

At magnitude 5.3, Caldwell 97 is visible to the naked eye from dark skies, easy in any binoculars.

Caldwell 97 — Open Cluster in Centaurus

NGC 3766

Open Cluster Excellent (73/100)

Magnitude 5.3^m OpenCluster Centaurus Visible

Credit: ESO. License: CC BY 4.0. (Wikimedia Commons)

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About C97

Description

NGC 3766 is a bright open cluster in Centaurus, about 5,500 light-years away. Known as the Pearl Cluster, it contains about 100 stars within 12 arcminutes, with many forming attractive patterns visible at low magnification.

Observing Tips

A fine cluster for small telescopes and binoculars. A telescope at 40-80x shows a rich grouping of stars with some color variety. Located near the Eta Carinae Nebula region. Best from southern latitudes in spring.

History

Discovered by Nicolas Louis de Lacaille in 1751 from South Africa. The Pearl Cluster nickname comes from its appearance as a scattering of luminous drops in a small telescope.

Fun Facts

NGC 3766 is about 20 million years old and contains a class of slowly pulsating B-type stars that has helped astronomers discover a new type of stellar variability mechanism.

Observe

1Properties

Magnitude 5.3

Angular Size 6.9′

Distance 5,800 ly

Description

Open Cluster [Distance: 5800 ly]

Position & Identifiers

RA 11h 36m 31.9s

Dec -61° 36' 43.2"

Constellation Centaurus

Catalog C97

Also known as NGC 3766

Physical size

14 light-years across — about 1.6× the Sun-to-Sirius 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

Easy on Seestar S50

At 150mm under B5 skies you should resolve about 182 of 530 members.

3Visibility

Set a location in User Settings to see visibility data.

Best season Feb – Apr (peak: Mar)

4 Eyepiece View

Telescope Eyepiece

125x TFOV: 0.4° Lim. mag: 13.6

C97 · 6.9′ 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.