The orientation of the Seyfert nucleus in Markarian 348

Multi-frequency observations of Mrk 348 are presented consisting of two epochs of MERLIN data at 5 GHz, ISOPHOT data at 170, 90, 60 and 25 mum, Nordic Optical Telescope images in the U, B, R and I bands and data at 1350 mum from the archive for SCUBA. The new optical images reveal a disrupted arm that ends towards the eastern companion of Mrk 348, consistent with the hypothesis that Mrk 348 and its companion form an interacting system. 5-GHz MERLIN imaging shows that only one of the radio components of Mrk 348 is polarized (P = 5 per cent). The broadband spectrum of Mrk 348 is flat between the radio and millimetre bands, suggesting that synchrotron emission extends to high frequencies. Mrk 348 has many of the characteristics of a radio-loud object. We discuss the orientation of the radio axis of Mrk 348 with respect to the line of sight. We conclude that the evidence is conflicting, and that the geometry in Mrk 348 is not well-described by a simple edge-on or face-on model.