Spectral variability of the NGC 4151 nucleus in 1972-1984.

During 1972-1984, more than 500 spectrograms of the NGC 4151 nucleus were obtained in the spectral regions centered on the H-alpha and H-beta lines, for 131 and 125 dates, respectively. Measurements of the equivalent widths of the emission lines are carried out and the results of independent photometric observations are presented. It is found that the radiation flux in the forbidden N1, N2, O I 6300 A, and SII 6717 and 6731 A lines remained constant during the observational period.