3C273

3C273 isquasar located inconstellation Virgo. It isoptically-brightest quasarour sky (m ~ 12.9),one ofclosest withredshift, z,0.16. The name signifies thatwas273rd object (ordered by right ascension) ofThird Cambridge CatalogRadio Sources (3C), published1959. The radio source was quickly associatedan optical counterpart, an unresolved stellar object. In 1963, Maarten SchmidtBev Oke publishedpairpapersNature reporting that 3C273 hassubstantial redshift, placingseveral billion light years away.

Prior todiscovery3C273, several other radio sources had been associatedoptical counterparts,first being 3C48. Also, many active galaxies had been misidentified as variable stars, includingfamous BL Lac, W Com, and AU CVn. However, it wasn't understood what these objects were, since their spectra were unlike thoseany known stars. 3C273 was the first objectbe identified as what we now know quasarsbe -- extremely luminous objects at cosmological distances.

3C273 isradio-loud quasar,was also one offirst extragalactic X-ray sources discovered1970. The luminosityvariable at nearly every wavelength from radio wavesGamma rays on timescales offew daysdecades. Polarization has been observedradio, infrared,optical light, suggesting that a fraction ofemitted lightsynchrotron radiation, created byjetcharged particles moving at relativistic speeds. Such jets are believedbe created byinteraction ofcentral black hole andaccretion disk. VLBI radio observations3C273 have revealed proper motionsome ofradio emitting regions, further suggestingpresencerelativistic jetsmaterial.

3C273located at (J2000) right ascension 12h 29m 6.7s, declination +2d 3m 8.6s,is visibleMaybothnorthern and southern hemispheres. Itbright enoughbe observedlarger amateur telescopes.