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16 Sagittarii — Star in Sagittarius

Magnitude 6.0m Star Sagittarius (Sgr) Visible
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1Physical Properties

Magnitude 5.95
Spectral Type O9.5II bright giant
Star Color White (B-V 0.02)

2Position & Identifiers

RA 18h 15m 12.9s
Dec -20° 23' 17.0"
Constellation Sagittarius (Sgr)
HR 6823
HIP 89440
HD 167263
SAO 186544
Flamsteed 16 Sgr
Double Cat 11191
SIMBAD

3How easy to spot?

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Equipment Bortle 3 Bortle 4 Bortle 5
Naked eye Hard+ Hard V. 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 May – Jul (peak: Jun)

5Survey Image

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6

Size Comparison

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7

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8

Spectral Classification

9

Hertzsprung-Russell Diagram

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Read: The Hertzsprung-Russell Diagram — Reading Stars Like a Map
10

Stellar Lifecycle

11

Blackbody Spectrum

12

Stellar Absorption Spectrum

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

13

Stellar Fusion

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14Stellar Notes

Companion A3V.
Sgr OB7; exciting star of HII region S35; NGC 6526.
SiII suspected of variability. Also classified O9II, O9III and O9.5II-III((n)).

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 6595
Easy
Open cluster
Open Cluster mag 7.0 0.7° Sagittarius
NGC 6589
Medium
Diffuse nebula
Diffuse Nebula mag 10.50 0.7° Sagittarius
M24
Small Sagittarius Star Cloud
Easy
Bright star cloud
Star Cloud mag 2.5 1.9° Sagittarius
9 Sgr
Easy
Hot blue O-type star
Star mag 5.97 4.8° Sagittarius
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