When is the best time to observe Caldwell 8?

Caldwell 8 is best observed from September through November, with peak visibility during October when it transits around midnight in the Northern Hemisphere.

Where is Caldwell 8 located in the sky?

Caldwell 8 lies in the constellation Cassiopeia at right ascension 01h 30m and declination +63° 18′.

What telescope do I need to see Caldwell 8?

At magnitude 9.5, Caldwell 8 is within reach of a 3-inch (80 mm) telescope from a moderate-Bortle site.

Caldwell 8 — Open Cluster in Cassiopeia

NGC 559

Open Cluster Good (50/100)

Magnitude 9.5^m OpenCluster Cassiopeia Visible

Credit: Meli thev. License: CC BY-SA 4.0. (Wikimedia Commons)

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About C8

Description

NGC 559 is a moderately rich open cluster in Cassiopeia, about 3,700 light-years away. It contains roughly 100 stars spread across 4 arcminutes, with the brightest members at about magnitude 10.

Observing Tips

Requires at least a 4-inch telescope to resolve. Located in the rich Milky Way star fields of Cassiopeia. Medium magnification (80-120x) works best. Circumpolar from northern mid-latitudes, best placed in autumn evenings.

History

Discovered by William Herschel on November 9, 1787. It is one of many open clusters Herschel cataloged in the star-rich region of Cassiopeia.

Fun Facts

NGC 559 is estimated to be about 200 million years old, making it a middle-aged open cluster. Studies have identified several red giant stars among its members.

Observe

1Properties

Magnitude 9.5

Angular Size 9.0′

Distance 3,700 ly

Description

Open Cluster [Distance: 3700 ly]

Position & Identifiers

RA 01h 29m 33.1s

Dec +63° 18' 03.6"

Constellation Cassiopeia

Catalog C8

Also known as NGC 559

Physical size

25 light-years across — about 2.9× the Sun-to-Sirius distance

2How easy to spot?

Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Easy	Medium+	Medium
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 30 of 528 members.

3Visibility

Set a location in User Settings to see visibility data.

Best season Sep – Nov (peak: Oct)

4 Eyepiece View

Telescope Eyepiece

125x TFOV: 0.4° Lim. mag: 13.6

C8 · 9.0′ 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.