RIANGULUM AUSTRALE, (pronounced tri-ANG-gyah-lum OSS-tray-lee),
NORMA, (pronounced NOR-mah) and
CIRCINUS (pronounced SUR-sih-nuss)
Triangulum Australe, the southern triangle, was introduced in 1603 by the German celestial cartographer Johann Bayer, as a southern equivalent of the long-established northern triangle Triangulum. It was apparently suggested though by Pieter Theodor about a century earlier. It is an easily found constellation near the Southern Cross.
Norma, the Surveyor's Level, was invented by Nicolas Louis de Lacaille, in the 1750's. Originally it was Norma et Regula, the carpenter's level and square, and some stars in the constellation were part of Ara and Lupus, but since Lacaille's time the outline of Norma has been altered, so that the stars which formally were α and β Normae, have now been placed in neighbouring constellations. Norma lies in a rich area of the Milky Way.
Circinus, the Drawing Compasses, is another small and obscure constellation introduced by Lacaille, appropriately near Norma the Level. A nearby and interesting spiral galaxy (ESO 97-G13) was found in Circinus in 1977. It peers through a small hole in the absorption near the galactic plane.
To find these constellations look south to find the pointers to the Southern Cross. Circinus and Triangulum Australisare below and slightly to the left of the pointers, with Norma to the left of the Pointers and at the same level.
Chart showing Triangulum Australe, Norma, and Circinus in June.The view is a little to the east of south at about 9 pm on June 1 or 7 pm on July 1.
Some stars and interesting objects in the Constellations
α Trianguli Australis is a magnitude 1.9 orange giant star 55 light years away.
β TrA is a magnitude 2.9 white star 33 light years away.
γ TrA is a magnitude 2.9 blue-white star 91 light years away.
NGC 5979 is a planetary nebula in a crowded field of stars. Small telescopes will distinguish the pale greyish-blue disk from a star.
NGC 6025 is a fine open cluster of about 30 white and yellow stars, visible in binoculars, lying 2000 light years away.
Normaγ2 Normae is a magnitude 4.0 yellow giant star 130 light years away. Next to it in the sky is the far more distant yellow supergiant γ1 Nor, at magnitude 5.0
δ Nor is a magnitude 4.7 white star 230 light years away
ε Nor appears as a double star in small telescopes, having components of magnitude 4.8 and 7.5, 490 light years away. Each of the components is a spectroscopic binary star, making this, in reality, a four star system.
ι1 Nor appears in small telescopes as a double star with magnitudes 4.9 and 8.5, lying 490 light years away, in a field sprinkled with stars.
NGC 5946 is a small, moderately bright globular cluster, lying in a beautiful star field. There a re a number of fairly bright wide pairs of stars in the cluster, especially south.
NGC 6087 is a very scattered open cluster of about 35 stars, 3600 light years away, visible in binoculars. There is a golden-yellow central star
Circinusα Circini is a magnitude 3.2 white star 46 light years away. There is a wide companion magnitude 8.8 star visible in small telescopes.
γ Cir consists of a very close pair of blue and yellow 5th magnitude stars, able to be separated in telescopes of 150 mm or more aperture, under high magnification. The long period binary system has a likely period of several centuries.
NGC 5315 is a bright small planetary nebula, fairly well defined in a beautiful field of stars.
Triangulum Australe and Circinus are circumpolar, that is never set, for places in New Zealand. Norma is a little nearer the equator and parts of the constellation dip below the horizon when it is to the south as seen from many parts of New Zealand.
The triangle is at its highest, to the left of, and slightly higher than, the Pointers at about midnight in early June or at 10 pm early July. Circinus is at its highest point about an hour earlier. At these times Norma will be above the other two constellations. Constellations reach their highest point in the sky four minutes earlier each day, so each succeeding month the constellations are highest 2 hours earlier.