Locating Sigma Octantis
At magnitude 5.6, Sigma Octantis is barely visible to the naked eye, making it a rather poor pole star, especially by comparison with the much brighter and more easily visible Polaris. Because of this, the Crux constellation is often preferred for determining the position of the South Celestial Pole.
Once Sigma Octantis' approximate position has been determined, either by the major stars in Octans or using the Southern Cross method, it can be positively verified using an asterism. Sigma, Chi, Tau and Upsilon Octantis are all stars of around magnitude 5.6, and form the distinctive shape of a trapezoid.
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