Characteristics of the variability of the nucleus of NGC 1275 in the optical in 1982-1994

We study the variability of the nucleus of NGC 1275 in the optical region u sing two samples of the photoelectric observations obtained with the 1.25-m telescope of the Crimean Astrophysical Observatory. The first sample conta ins one series of 379 measurements of the nucleus brightness obtained with the scanning spectrophotometer during 35 nights from 12.XI.1982 to 23.X.198 7. The slit ax = 80 Angstrom was centered at the wavelength lambda 5200 Ang strom. The second sample contains 5 series of 820 measurements obtained sim ultaneously in each of the UBVRI bands during 37 nights from 22.XII.1989 to 29.XII.1994. The observations during one night lasted from 0.5 up to 8.7 h ours. Each of the 6 independent observational series was analyzed separatel y. An analysis has been made of the variations both on a time scale of years a nd of single nights (intra-night). Ratios of Standard Deviations (SD) of th e variable flux to the error of the observations (a) were calculated for ea ch night, and the parameters of Structure Functions (SF) were used as indic ations of the intranight variability. We assume that the intranight variati ons of the flux are real, when SD greater than or equal to 3 sigma. There w e:re 8% of such nights in 1982-1987, and about 40% of nights showed intrani ght variability in 1989-1994. SFs of the intranight variations for all series of observations are charact erized by the two slopes log(SF) similar to b log dt: for time scales less than 4 hours the slope is in the range 0.25 less than or equal to b less th an or equal to 0.66, for the time scales less than 9 hours it is in the ran ge 0.66 less than or equal to b less than or equal to 1.19. These data allo w us to conclude that during 1982-1994 two processes operated in the nucleu s of the NGC 1275 galaxy, causing variations of its flux in the optical on a time scale of several hours. One of the processes was a mixture of shot-n oise and flicker-noise, and the second one was nearer to pure shot-noise. The SF slopes for the time scale of years were in the range of 0.06-0.14. T hey evidenced that on the time scale years the process was absent, or a pur e flicker-noise is operated. The evolution of the processes acting in the n ucleus from 1968-1980 to 1982-1994 is mentioned. A years process is evolved in accordance with the general flux variations, but an activity of the int ranight variations is increased with the decreasing of the general brightne ss of the nucleus. All obtained data are discussed from the point of view o f the current models of a powering mechanism.