Some writers state that the Segment was Perseus’ sword, which he used to decapitate the Gorgon Medusa. Various sources include different stars, but the most frequently mentioned are, in order, Eta, Gamma, Alpha (named Mirfak), Psi (ψ), and Delta (δ) Persei.
Our last fall asterism is big and bright: the Segment of Perseus. If you see a subtle glow at the southeast end of the Cascade, you’ve found the Jolly Roger Cluster (NGC 1502), an open cluster that glows at magnitude 5.7. The other stars glow between 7th and 9th magnitudes on either side of it. The easiest way to find the Cascade is to locate its brightest star, 5th-magnitude SAO 12969, that sits in the center. Because it’s 2.5° long, it looks best through binoculars - that’s how its discoverer, amateur astronomer Lucian Kemble, found it.Ī magnification of 15x works best for framing the 15 stars in this starry chain. The next fall asterism, Kemble’s Cascade, lies north of Perseus in the constellation Camelopardalis. Other celestial mapmakers reinvented it as Musca Borealis the Northern Fly (from which the asterism’s name derives) and Lilium the Lily. In the early 17th century, Dutch cartographer Petrus Plancius added the magnitude 5.3 star 33 Ari to this trio and formed the now-defunct constellation Apes the Bees. The brightest of the three is 41 Ari (magnitude 3.6), followed by 39 Ari (magnitude 4.5) and 35 Ari (magnitude 4.7). For that reason, the Coathanger carries the designation Collinder 399. 399 in a catalog of 471 open clusters he compiled.
Swedish astronomer Per Arne Collinder included this group as No. The combined magnitude of all the Coathanger’s stars is 3.6, but it’s not bright because the light is spread across an area 1° wide. The brightest are 4 Vulpeculae (magnitude 5.1), 5 Vul (magnitude 5.6), and 7 Vul (magnitude 6.3). Ten of the Coathanger’s stars rise above 7th magnitude. Although you can spot this stellar gathering with just your eyes, it looks best through binoculars. Continue that line another 4½°, and you’ll find the Coathanger. From it, draw a line 3° to the south to Anser (Alpha Vulpeculae), which glows at magnitude 4.4.
It’s the 3rd-magnitude double star that’s the head of Cygnus the Swan. Now head northwest about one-quarter of the way across the sky and find Albireo (Beta Cygni). Many early celestial cartographers pictured a stream of water flowing out of the Water Jar and into the mouth of Piscis Austrinus the Southern Fish. The central star, Zeta, is a double star made of Zeta1 Aqr (magnitude 4.4) and Zeta2 Aqr (magnitude 4.6), which combine to make the star’s apparent magnitude 3.7. The four stars are Gamma, Eta (η), Pi (π), and Zeta (ζ) Aquarii. It appears as a triangle with a central point. Proceed west about twice the diameter of the Circlet, and you’ll arrive at the Water Jar in the constellation Aquarius. A cord leads east to Alrescha (Alpha Piscium), and another heads northward to the eastern fish, which, unfortunately, isn’t nearly as easy to spot as the one marked by the Circlet. The Circlet marks the head of the western fish in this constellation.
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