Detection of Optical Synchrotron Emission from the Radio Jet of 3C 279

We report the detection of optical and ultraviolet emission from the kiloparsec-scale jet of the well-known quasar 3C 279. A bright knot, discovered in archival V - and U -band Hubble Space Telescope Faint Object Camera images, is coincident with a peak in the radio jet ~0 6 from the nucleus. The detection was also confirmed in Wide Field Planetary Camera 2 images. Archival Very Large Array and MERLIN radio data are also analyzed, and these data help to show that the high-energy optical/UV continuum and the spectrum are consistent with a synchrotron origin from the same population of relativistic electrons responsible for the radio emission.