Multiwavelength observations of PKS 2255-282

During high radio frequency active galactic nucleus monitoring, we observed a major millimeter wave outburst from PKS 2255-282 in 1997 and initiated a campaign for multifrequency radio monitoring and VLBI imaging of the sourc e. In 1998 January the EGRET instrument on board the Compton Gamma Ray Obse rvatory detected a bright high-energy gamma-ray outburst from its direction . Thus, we had the unique opportunity to monitor the source in detail at va rious radio frequencies already before the detection of the gamma-ray outbu rst. We also initiated multiwavelength follow-up observations. In this pape r we present multiwavelength data for PKS 2255-282 before and after the gam ma-ray outburst. Further, based on the observations, we estimate some physi cal parameters for this source and discuss the various emission mechanisms possibly involved during this outburst.