Telescopium

Telescopium is a minor southern constellation created in the 18th century by Nicolas Louis de Lacaille, a French astronomer and student of the southern skies. Its name is a Latinized form of the Greek word for telescope. One of several constellations depicting scientific instruments drawn up by Lacaille, it was later much reduced in size by Francis Baily and Benjamin Gould. The brightest star in the constellation is Alpha Telescopii, a blue-white subgiant with an apparent magnitude of 3.5, followed by the orange giant star Zeta Telescopii at magnitude 4.1. Eta and PZ Telescopii are two young star systems with debris disks and brown dwarf companions. Telescopium hosts two unusual stars with very little hydrogen that are likely to be the result of two merged white dwarfs: HD 168476, also known as PV Telescopii, is a hot blue extreme helium star, while RS Telescopii is an R Coronae Borealis variable. RR Telescopii is a cataclysmic variable that brightened as a nova to magnitude 6 in 1948. ... Stars. With an apparent magnitude of 3.5, Alpha Telescopii is the brightest star in the constellation. It is a blue-white subgiant of spectral type B3IV which lies around 250 light-years away. Close by Alpha are the two blue-white stars sharing the designation of Delta Telescopii. Delta¹ is of spectral type B6IV and apparent magnitude 4.9, while Delta² is of spectral type B3III and magnitude 5.1. ... At least four of the fifteen stars visible to the unaided eye are orange giants of spectral class K. The second brightest star in the constellation is Zeta Telescopii of apparent magnitude 4.1 and spectral type K1III-IV. ... Epsilon Telescopii is another double star, though this time a true binary system. Epsilon Telescopii A is an orange giant of spectral type K0III with an apparent magnitude of +4.52, with a 13th magnitude companion, Epsilon Telescopii B, 21 arcseconds away from the primary, and just visible with a 15 cm telescope on a dark night. The system is 409 light-years away. Iota Telescopii and HD 169405—magnitude 5 orange giants of spectral types K0III and K0.5III respectively — make up the quartet. Deep sky objects. The globular cluster NGC 6584 lies near Theta Arae and is 45000 light-years distant. It is an Oosterhoff type I cluster, and contains at least 59 variable stars, most of which are RR Lyrae variables. The planetary nebula IC 4699 is of 13th magnitude and lies midway between Alpha and Epsilon Telescopii. There are a group of twelve galaxies spanning three degrees in the northeastern part of the constellation. They lie around 120 million light-years from our own galaxy. This group is known as the Telescopium group or AS0851. The brightest is the elliptical galaxy NGC 6868. To the west lies the spiral galaxy NGC 6861. These are the brightest members of two respective subgroups within the galaxy group, and are heading toward a merger in the future. Occupying an area of around 4' x 2', NGC 6845 is an interacting system of four galaxies—two spiral and two lenticular galaxies—that is estimated to be around 88 megaparsecs (287 million light-years) distant. SN 2008DA was a type II supernova observed in one of the spiral galaxies, NGC 6845A in June 2008. [Telescopium. Wikipedia]