DETECTION OF AN X-RAY PERIODICITY IN THE SEYFERT-GALAXY IRAS-18325-5926

We report the detection of a 5.8 x 10(4) a periodicity in the 0.5-10 k eV X-ray light curve of the Seyfert galaxy IRAS 18325-5926, obtained f rom a 5-d ASCA observation. Nearly nine cycles of the periodic variati on are seen; it shows no strong energy dependence and has an amplitude of about 15 per cent, Unlike most other well-studied Seyfert galaxies , there is no evidence for strong power-law red noise in the X-ray pow er spectrum of IRAS 18325-5926. Scaling from the QPOs found in Galacti c black hole candidates suggests that the mass of the black hole in IR AS 18325-5926 is similar to 6 x 10(6) -4 x 10(7) M..