Observations of core sources in Seyfert and normal galaxies with the Westerbork synthesis radio telescope at 1415 MHz.

Eight Seyfert and ten normal galaxies have been observed with the sWesterbork Synthesis Radio Telescope at a frequency of 1415 MHz. sUnresolved sources (<7") were detected in the nuclei of all galaxies spreviously classified as Seyferts. Of these NGC 3077 is much weaker than sthe others, which is compatible with the absence of broad emission lines sand NGC 4670, for which the Seyfert classification was tentative, has a snuclear source comparable to the well-established Seyferts. For two sSeyfert galaxies upper limits of 5% were put on the degree of linear spolarisation. No radiation is detected from Markarian 205 (Weedman, s1970). Th oniy three of the ten "normal" galaxies radio emission was sdetected: NGC 3310 (point-source in the nucleus), NGC 3726 (two sources ssymmetrically placed with respect to the nucleus) and NGC 4736 (triple ssource, with the middle one in the nucleus). The structure shows no sevidence for relativistic effects (Ryle and Longair, 1967). The sobservations show that complex structures observed in radio galaxies sexist also within normal galaxies. The 1415 MHz power of the other 11 to s12 magnitude galaxies is shown to be less than about 1019 W Hz-1 ssterad-1. The analysis shows that there is a relation between the 1415 sMHz and lO power for the nuclei of Seyfert galaxies. Similar relations smay exist between the powers at 1415 MHz and those in the optical scontinuum and H This is briefly discussed in terms of the recent model sgiven by Cavaliere et al. (1970), where the electrons radiating at radio swavelengths originate from the small core, where the infrared radiation sis emitted. Key words: 21 cm radio continuum - Seyfert galaxies - normal sgalaxies - core sources