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Octans is a rather non-descript constellation
which includes the southern polar region. The constellation was devised
by Nicolas Louis de Lacaille in 1752. It commemorates the octant, which
was invented by John Hadley in 1730. In fact the full name of the
constellation is "Octans Hadleianus".
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The instrument divided the circle into eight parts, which facilitated
the making of angular measurements in both astronomy and navigation.
Most of Octans' stars are fifth magnitude,
including sigma Octantis, the Southern Pole Star (which is actually
about a degree from the true south pole and moving slowly away from it).
Rather strangely, the brightest star in the constellation is nu
Octantis, an orange giant 64 light years away.
Octans has one notable binary, a few variables, and little else of
interest.
Double stars:
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Lambda Oct is a double with yellowish-white primary and orange-yellow companion: 5.6, 7.3;
PA 63º, separation 3.5".
Variable stars:
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Epsilon Oct is a semi-regular variable: 4.6 - 5.3 every 55 days
or so.
Sigma Oct is a delta Scuti variable, 5.45 - 5.5 every 2h 19m 41s.
For a more detailed appreciation of Octans, visit the Binocular Section.
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© Richard Dibon-Smith.
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