Five Star Circlet of Pisces Asterism Is Below Great Square of Pegasus

Summary: The five star Circlet of Pisces asterism is below the Great Square of Pegasus, appearing in the south at mid-northern latitudes in October.

Pisces illustration, Alexander Jamieson’s A Celestial Atlas, Plate XXII (1822): Public Domain, via U.S. Naval Observatory

The five star Circlet of Pisces asterism is below the Great Square of Pegasus and appears in the south at mid-northern latitudes in October.

The Circlet of Pisces asterism resides in Pisces the Fishes, a graceful, v-shaped constellation comprising two fishes. The constellation’s two fishes are linked by starry ribbons that are knotted together at Alrescha (Alpha Piscium; α Piscium; Alpha Psc; α Psc), the noticeable, variable binary star system at the vee’s tip.

The constellation’s two fishes cradle the Great Square of Pegasus asterism in Pisces’ northwestern neighbor, Pegasus the Winged Horse constellation. The five star Circlet of Pisces asterism represents the western fish, which leaps or swims to the south of the Great Square of Pegasus asterism. A starry triangle marks the eastern fish, which leaps or swims toward Andromeda the Chained Princess constellation, to the east of the Great Square of Pegasus asterism.

The official constellation chart for Pisces the Fishes constellation presents the Circlet of Pisces asterism as a five-sided shape, or pentagon (Ancient Greek: πέντε, pénte, “five” + -γωνος, -gōnos, “angled”). The International Astronomical Union collaborates with Sky & Telescope magazine in releasing approved constellation charts. The IAU was founded in 1919 as an international association with approval of “unambiguous astronomical nomenclature” as a key task.

The five stars officially shaping the Circlet of Pisces asterism reside in the western reaches of Pisces the Fishes constellation. The quintet squeezes between the Great Square of Pegasus asterism immediately to the north and, immediately to the south, the celestial equator, the imaginary great circle planed outward from Earth’s equator onto the imaginary celestial sphere.

Iota Piscium (Iota Psc; ι Piscium; ι Psc) links the western fish, as the Circlet of Pisces asterism, with its starry ribbon. The yellow-white dwarf shines as the second brightest star in the Circlet of Pisces asterism. Iota Piscium marks the asterism’s easternmost point.

Theta Piscium (Theta Psc; θ Piscium; θ Psc) lies northwest of Iota Piscium. The orange giant star is the third brightest star in the Circlet of Pisces asterism.

Gamma Piscium (Gamma Psc; γ Piscium; γ Psc) marks the Circlet of Pisces asterism’s westernmost point. The yellow giant shines as the brightest star in the Circlet of Pisces asterism.

Kappa Piscium (Kappa Psc; κ Piscium; κ Psc) lies southeast of Gamma Piscium and marks the Circlet of Pisces asterism’s southernmost point. The multiple star system of three components is the asterism’s dimmest star.

Lambda Piscium (Lambda Psc; λ Piscium; λ Psc) lies slightly northeast of Kappa Piscium and slightly southwest of Iota Piscium. The bluish-white star ranks as fourth brightest in the five star Circlet of Pisces asterism.

Omega Piscium (Omega Psc; ω Piscium; ω Psc) frames the five star Circlet of Pisces asterism to the east as the loop of the constellation’s southwestern ribbon around the western fish’s tail. The yellow-white subgiant is suspected of being a close binary star system, with a close orbit and a capacity for shared evolution via mass transfers.

Beta Piscium (Beta Psc; β Piscium; β Psc) frames the five star Circlet of Pisces asterism to the west as Pisces the Fishes constellation’s westernmost visible star to the naked eye. Beta Piscium’s traditional name, Fum al Samakah, derives from the Arabic phrase for “mouth of the fish.” Illustrations of the constellation, however, vary in placement of Beta Piscium within the western fish’s head. Based on telescopic observations by the United Kingdom’s First Astronomer Royal, John Flamsteed (Aug. 19, 1646-Dec. 31, 1719), and published posthumously in 1729, Atlas Coelestis places Fum al Samakah in the western fish’s upper lip. A Celestial Atlas, published by Scottish rhetorician Alexander Jamieson (1782-1850) in 1822, marks the western fish’s eye with Fum al Samakah.

The takeaway for the five star Circlet of Pisces asterism is its easy noticeability below the Great Square of Pegasus asterism.

Circlet of Pisces and other stars in Pisces the Fishes constellation: International Astronomical Union and Sky & Telescope, CC BY 4.0 International, via International Astronomical Union (IAU)

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

Pisces illustration, Alexander Jamieson’s A Celestial Atlas, Plate XXII (1822): Public Domain, via U.S. Naval Observatory @ http://aa.usno.navy.mil/library/

Circlet of Pisces and other stars in Pisces the Fishes constellation: International Astronomical Union and Sky & Telescope, CC BY 4.0 International, via International Astronomical Union (IAU) @ (image URL @ https://www.iau.org/public/images/detail/psc/)

For further information:

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Fisher, Mark. “Fum al Samakah.” Glyph Web eSky (Electronic Sky) > Stars.
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Available @ http://stars.astro.illinois.edu/sow/psc-w-p.html

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Available @ https://earth-and-space-news.blogspot.com/2017/10/great-square-of-pegasus-asterism-has.html

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Available @ http://earthsky.org/constellations/pisces-heres-your-constellation

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Stern, David P. “Precession.” NASA Goddard Space Flight Center (GSFC) International Solar Terrestrial Physics (ISTP) > From Stargazers to Starships. Last updated Sept. 17, 2004.
Available @ http://www-istp.gsfc.nasa.gov/stargaze/Sprecess.htm

Upton, Winslow. "Constellation Study V." Popular Astronomy, vol. I, no. 7 (March 1894): 308-315.
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