The velocity field of UGC 6697 revisited

The edge-on galaxy UGC 6697 has a peculiar morphological appearance: a high surface brightness SE component and what appears to be a tidal tail with b lue color and low surface brightness extending toward the NW, as dramatical ly evidenced in subarcsecond broad band images taken with the VLT and in a deep H-alpha frame. Long-slit spectroscopy shows a 500 km s(-1) rigid-body rotation curve with a sudden central velocity jump, of more than 200 km s(- 1) amplitude. Fabry-Perot observations of the H-alpha emission line enable us to trace a detailed 2D velocity field, confirming the complex kinematica l behaviour, particularly in the circumnuclear region where multiple veloci ty components are clearly superposed on the same line of sight. This region hosts a double nucleus and shows sudden color and metallicity gradients, w hich can be reconciled with the complex velocity field assuming the presenc e of a second galaxy hidden behind the main body of UGC 6697.