1ES 1741+196: a BL Lacertae object in a triplet of interacting galaxies?

We present subarcsecond resolution imaging and spectroscopy of the BL Lac o bject 1ES 1741+196 and neighboring galaxies. Based on 2-dimensional modelli ng, the host galaxy of 1ES 1741+196 is a very bright and large elliptical g alaxy (M-R = -24.85, r(e) = 51.2 kpc) whose overall luminosity distribution deviates significantly from a de Vaucouleurs profile. It is one of the mos t luminous and largest BL Lac host galaxies known. Closeby to 1ES 1741+196 we found two companion galaxies at the same redshif t as the BL Lac itself. They are at projected distances of 7.2 and 25.2 kpc , respectively. The closer companion galaxy can be best modelled by a Sa-ty pe galaxy, whereas the more distant companion galaxy is an elliptical. This is supported by their spectra. We detected a tidal tail emerging from the closer companion galaxy which is possibly connected with the more distant g alaxy. Its surface brightness increases towards the closer companion galaxy , which suggests that material has been released from that galaxy due to ti dal forces. The flat luminosity profile (beta = 0.15), high ellipticity (epsilon = 0.35 ) of the host galaxy of 1ES 1741+196 as well as its position angle along th e impact parameter to the neighboring galaxies can be the result of tidal i nteraction. 1ES. 1741+196 may be a BL Lac object in a triplet of interactin g galaxies.