Observations of fuors. FU Orionis during 1984-1990 - Notable variation in the brightness decline rate Results of FU Ori photometry on Mt. Maidanak during 1984-1990 areanalyzed. In December 1987, the fuor exhibited a stepwise decrease inbrightness by 0.1 mag, after which the decrease rate of FU Oribrightness grew threefold (0.07 mag/yr compared to 0.02 mag/yr during1961-1980), while the U-B color parameter decreased to +0.82 mag. Adistance modulus of 8.1 +/- 0.2 mag is confirmed on the basis ofphotometry of 65 stars in the neighborhood of FU Ori. UBVR magnitudes ofvariable and emission-line stars in the FU Ori field are also presented;brightness variations are suspected for seven stars.
