Astronomy in the Park
Join the San Antonio Astronomical Association for the Astronomy in the Park Program on Wednesday nights beginning at sunset. Astronomy in the Park is held each Wednesday, weather permitting, at McAllister Park, 13102 Jones Maltsberger Rd. [map]
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3C 273
By Scott Logan on Sunday June 28, 2009 07:18:21 PM
The recurrent nova, U Scorpii should erupt soon. U Scorpii is located north of Antares and east of the head of the Scorpion. Now is the time to start watching. For more information about U Scorpii, visit the S&T website.
This is the time of year that the Little Dipper rises up from Polaris like a balloon on a string. Spotting the Little Dipper will probably require you to get away from San Antonio’s light dome.
About an hour before sunrise on Wednesday Venus and Mars lie less than 10° south of the Pleiades. A good time to try out your photographer’s skills.
It looks like fireworks displays will be few and far between in South Central Texas this Fourth of July because of the extremely dry conditions. So look to the skies for a fireworks show. In the east you’ll find Vega high in the east-northeast. Closer to the horizon you’ll find Deneb and Altair as the Summer Triangle rises. To the south you’ll find Antares with the Moon nearby. In the west, Arcturus and Spica are well up in the sky with Saturn and Regulus much closer to the horizon. And for an extra treat, in the deep south, Omega Centauri lies just to the west of due south.
3C 273 is a quasarA quasar is the bright center of a galaxy, believed to be powered by a supermassive black hole. The word "quasar" is derived from quasi-stellar radio source, because this type of object was first identified as a kind of radio source. Quasars also are called quasi-stellar objects (QSOs). Thousands of quasars have been observed, all at extreme distances from our galaxy. in the constellation Virgo, about 4¾° northwest of γ Virginis and 3½° north-northeast of η Virginis. Using the chart below you will be able to star-hop to this 13th magnitude quasar.
3C 273 is the 273 object listed in the 3rd Cambridge Catalog of Radio Sources, published in 1959. In 1962 3C 273 became the first object identified as a quasar. At the time the unusual emmission spectrum of the object drew much more interest than the radio emmissions. In 1970 it was discovered to also be a source of X-rays. The luminosity of 3C 273 is variable and visible at nearly every wavelength of the electromagnetic spectrum, from radio waves through Gamma rays.
It is, optically, the brightest quasar in the sky with an average magnitude of 12.9 (it varies from 12 to 13.3) and one of the closest, with a redshift of 0.158. This redshift vields a distance of 2.44 Giga lightyears. It is also one of the most luminious quasars known, with an absolute magnitude of -26.7 and it has a mass of 886 ± 187 M☉. 3C 273 is one of the most distant objects visible in a backyard telescope. It should be an easy target for a 10" telescope under dark skies.
3C 273 has a large visible jet, about 200 kilo lightyears long with an apparent size of 23". In the mid 1990’s optical observations of the jet by the Hubble Space Telescope revealed that the jet has a structured morphology of repeated bright knots interlaced by areas of weak emissions.
Image of 3C 273 from the Digital Sky Survey
