Observing Antlia and Pyxis
The Constellations of the Air Pump and the Compass
Antlia the Air Pump and Pyxis the Compass are Southern Hemisphere constellations that are home to dim, deep-sky objects.
Antlia the Air Pump and Pyxis the Compass are two constellations in the Southern Hemisphere that can be seen by Northern Hemisphere viewers who live farther south. May is a good month to view these two constellations, regardless of the hemisphere you are in. The constellations lie next to each other in the sky, east of Canis Major and Puppis and north of Vela.
The Constellation of Antlia the Air Pump
Antlia is located east of Pyxis, north of Vela, south of Hydra, and west of Centaurus. Antlia's stars are so dim that the constellation was not even created until the 18th century. Nicolas Louis de Lacaille created many constellations out of regions of dark sky that were simply lumped in with neighboring constellations. These new constellations Lacaille named after new or important instruments of his time. Antlia, for example, is named after an air pump.
While there is a large stretch of galaxies that cross Antlia, they are so distant and dim that they are not observable by the majority of amateur astronomers. One 11th magnitude galaxy, NGC 2997, can be seen by larger telescopes near the border of Pyxis. William Herschel discovered this spiral galaxy in 1793 is approximately 55 million light-years away.
A well-known nebula, called the Eight-burst Nebula, lies on the border with Antlia and Vela but is usually considered as part of the Vela constellation. The magnitude 8 nebula has a double star system at its core.
The Constellation of Pyxis the Compass
Pyxis is another constellation created by Nicolas Louis de Lacaille. It represents a ship's compass, not to be confused with Circinus, which represents a drawing compass. Pyxis is located between Puppis, Hydra, Antlia, and Vela.
The Alpha and Beta stars of Pyxis are located in the southern part of the constellation. Alpha Pyxidis is magnitude 3.68 and lies 845 light-years away. Just over two degrees to the south is Beta Pyxidis at magnitude 3.97 lying 388 light-years away. Both Alpha and Beta have star clusters lying a half degree to the northwest. Alpha's star cluster is NGC 2658 at magnitude 9. Beta's star cluster is NGC 2635 at magnitude 11.2.
Two other star clusters make good targets in Pyxis due to their relative brightness. One is NGC 2627, a magnitude 8 star cluster lying three and a half degrees northwest of Alpha or just a half degree southwest of Zeta Pyxidis, a magnitude 4.86 star. The other lies in the southeast corner of the constellation. NGC 2818 is a magnitude 8.19 grouping about seven and a half degrees east of Beta.
