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Theta Circini — Star in Circinus

Star Circinus (Cir) Visible
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1Physical Properties

Magnitude 5.11
Range 4.81 - 5.65
Variable Type Gamma Cassiopeiae (Eruptive Be Star)
Spectral Type B4Vnpe
Star Color White (B-V 0.00)

2Position & Identifiers

RA 14h 56m 44.0s
Dec -62° 46' 51.0"
Constellation Circinus (Cir)
HR 5551
HIP 73129
HD 131492
Bayer Theta
Variable ID The Cir
SIMBAD

3How easy to spot?

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Equipment Bortle 3 Bortle 4 Bortle 5
Naked eye Medium Hard+ Hard+
50mm finder Easy Easy Easy
150mm scope Easy Easy Easy
Easy Medium Hard Very hard Impossible

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

4Visibility

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Best season Mar – May (peak: Apr)

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5

Size Comparison

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6

Compare Stars

7

Spectral Classification

8

Hertzsprung-Russell Diagram

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Read: The Hertzsprung-Russell Diagram — Reading Stars Like a Map
9

Stellar Lifecycle

10

Blackbody Spectrum

11

Stellar Absorption Spectrum

Simulated absorption spectrum based on spectral type. Hover over lines to identify elements.

12

Stellar Fusion

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13Stellar Notes

Gamma Cas 5.02 - 5.44V. Amp. 0.03 on time scale 2d reported. H alpha varies.
Sco-Cen assoc.
H alpha variable.

Survey Image

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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.

AX Cir
Hard+
Pulsating variable, period 5.3d
Variable Star mag 5.87 1.1° Circinus
Delta Cir
Easy
Hot blue O-type star
Star mag 5.09 3.0° Circinus
NGC 5617
Easy
Rich open cluster
Open Cluster mag 6.3 3.8° Centaurus
NGC 5189
Hard+
Planetary nebula — try an OIII filter
Planetary Nebula mag 10.0 9.5° Musca
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