Nuclear activity of NGC 4151 as inferred from UBVRI observations in 1989-2000

We present our broadband UBVRI observations of the nucleus of the Seyfert g alaxy NGC 4151 from 1989 until 2000 at three astronomical observatories: th e Crimean Station of the Sternberg Astronomical Institute, the Special Astr ophysical Observatory in the Caucasus, and the Maidanak Observatory of the Ulugbek Astronomical Institute in Uzbekistan. All data have been reduced to a single system and are given for an A = 27 " .5 aperture. Regular R and I observations show that the pattern of optical variability is the same in a ll bands; the relative variability amplitude decreases from U to V, but it is even slightly larger in R than in V. The variability amplitude of the co mponent fluctuating on time scales of several months is proportional to the UBV flux from the component varying on times scales of several years. The correlation between the slow and rapid components significantly weakens in the red, and no correlation has been found between the flux from the slow c omponent and the amplitude of the rapid component in R. The color character istics correspond to the recombination radiation from an optically thick pl asma beyond the Balmer limit. (C) 2001 MAIK "Nauk/Interperiodica".