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IC 166 — Open Cluster in Cassiopeia

Open Cluster Fair (34/100)
Magnitude 11.7m OpenCluster Cassiopeia (Cas) Visible
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1Properties

Magnitude 11.7
Angular Size 5 arcmin
S Cl, nebulous?

Position & Identifiers

RA 01h 52m 23.8s
Dec +61° 51' 09.4"
Constellation Cassiopeia (Cas)
Catalog IC 166

2How easy to spot?

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Telescope Bortle 3 Bortle 4 Bortle 5
80mm refr. Hard Hard V. hard+
150mm Newt. Medium+ Medium Hard+
C8 203mm Medium+ Medium+ Medium
Easy Medium Hard Very hard Impossible

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

Easy on Seestar S50

3Visibility

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Best season Sep – Nov (peak: Oct)

4 Eyepiece View

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125x TFOV: 0.4° Lim. mag: 13.6
N E

IC 166 · 5.0′ diameter

5 Best Magnification

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6 Classification Decoder

Nearby in the Sky

Other targets within a few degrees — pan your scope a little and keep exploring.

Visibility scores assume a 150 mm Newton at Bortle 4.

NGC 663
Easy
Open cluster
Open Cluster mag 7.1 1.0° Cassiopeia
NGC 654
Easy
Rich open cluster
Open Cluster mag 6.5 1.0° Cassiopeia
NGC 659
Easy
Open cluster
Open Cluster mag 7.9 1.5° Cassiopeia
NGC 637
Easy
Open cluster
Open Cluster mag 8.2 2.4° Cassiopeia
1 Per
Hard+
Eclipsing binary, period 25.9d
Variable Star mag 5.52 6.7° Perseus
NGC 281
Medium+
Emission nebula — try an OIII filter
Emission Nebula mag 7.0 9.2° Cassiopeia
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