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SEXTANS
The Sextant
Sextans - Celestial Atlas by Alexander Jamieson - 1822
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Sextans was named by astronomer Johannes Hevelius in the 17th century after the sextans uraniae, otherwise known as the astronomical sextant. At that time the sextant was an absolutely essential tool for astronomers. It was also an essential tool for sailors. It measured the angle of celestial objects above the horizon, which helped determine the exact location of a ship at sea.
There is not much to observe in the constellation Sextans. It is one of the faintest constellations in the sky. The brightest star, Alpha Sextanius, has a magnitude of only 4.49. But if the night is dark enough, and you look very carefully just underneath Leo, you will sea a group of very dim stars that really do form the shape of an a sextant.
There is one notable object in the constellation, NGC 3115, one of two galaxies known as the Spindle Galaxy. It is a bright lenticular galaxy seen almost edge on, located about 32 million light years away. At the centre of the galaxy is a supermassive black hole, approximately one billion times as massive as our Sun.
So far five extrasolar planets have been discovered in Sextans orbiting four stars. Unfortunately these stars are all beyond naked eye visibility, and the planets are all the size of Jupiter or larger. For more information see NASA's planet quest.
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