A flare in the optical spectrum of 3C 273.

Flaring has been observed in 3C 273 in the BVRI spectrum during January 1983. The increase in luminosity is especially pronounced at longer wavelengths and amounts to as much as half a magnitude increase in brightness over quiescent values. These observations complement and are consistent with similar observations in the millimeter to IR made at about the same time by Robson et al. They support the notion that the emission over a frequency range of millimeter to optical originates in the same region of the source, and that the flare propagates to longer wavelengths while decaying at shorter wavelengths.