Constellation Data

Name: OCTANS Translation: Octant Abbreviation: Oct Genitive: Octantis Size: 50 Regions: Circumpolar, Southern Located Between: Hydrus, Apus, Chameleon RA: -- hours Decl: -85 degrees Season: Anytime

What is the Genitive form? What is Right Ascension (RA)? Is this constellation ever visible from my latitude? What is Declination? Where should I look for a constellation on a date before or after its midnight culmination? What is Midnight Culmination?

Description

Octans the Octant is devoid of bright stars, but three faint stars (not numbered by brightness) make a small triangle. The south celestial pole actually lies within Octans. The nearest easy-to-spot star to the south pole is Beta-Hydri in Hydrus the Little Snake. No brighter star than Achernar (alpha-Eridani) is closer to the south celestial pole, which lies midway between Achernar (Eridanus) and Crux.

Legend: In the constellation chart above...
• Star colors represent their spectral types (even for double stars).
• Bright star labels are yellow; significant other stars are labelled in magenta.
• The size of each star indicates its relative magnitude.
• Constellation names are light blue.
• Grid lines represent either 10 degree intervals of declination above or below the equator, or intervals of one hour (=15 degrees) of right ascension (measured along the equator).
• Messier object numbers are pink.
• Galaxies are ovals: blue if spiral, yellow if elliptical, light blue if irregular.
• Globular clusters are gold starbursts.
• Open clusters are dotted white circles.
• Planetary nebula are green diamonds.
• Bright nebula are magenta squares.
• Dark nebula are grey rectangles.
• Green x's are x-ray sources.
• Purple O's with a diagonal slash through them are quasars.

Special Stars

Sigma-Octantis, the closest naked-eye star to the south celestial pole. Magnitude: 5.5 (faint). Distance: 121 LY. Declination: -88 degrees 57 minutes 21 seconds. (Is it closer to the south pole than Polaris is to the north pole?)

Table of 25 Brightest Stars.
What is apparent stellar magnitude?

©1997 Welcome to the Basic Celestial Phenomena web site. To provide explanations of basic observational astronomy to students, teachers, families, and visitors to planetariums these pages have been written by an ex-OBU Planetarium Director, Kerry Magruder; the OBU Natural Sciences Coordinator, Mike Keas; and some of the students who work in the OBU planetarium.

The source for the logo is not a medieval woodcut!

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