Light-time effect in RT Persei

The minimum time residuals (O–C) of RT Persei, obtained by using all the times of minima is interpreted in terms of light-time effect, caused by the presence of two more distant components. This system possesses a third body of a mass of about 0.74M with 41.86 yr orbital period moving in an orbit of eccentricity equal to 0.3, while the hypothetical fourth body of an approximate mass of 0.59M moving with an orbital period of 100 years has an eccentricity equal to 0.6. The need to study this system astrometrically should be emphasized.