THE OPTICAL STRUCTURE AND LOCAL ENVIRONMENT OF THE BL-LAC OBJECT 1E-1415.6+2557

The X-ray-selected BL Lac object 1E 1415.6 + 2557 is of current intere st, because its host galaxy morphology and clustering environment appe ar to be inconsistent with standard beaming models for BL Lac objects. The host galaxy of 1E 1415.6 + 2557 was originally identified as a lu minous spiral galaxy, but more recently this galaxy has been classifie d as an isolated giant elliptical galaxy with an optical jet. We prese nt deep multicolour high-resolution optical images of this object, and confirm that the host galaxy is a giant elliptical galaxy. We find th at the optical 'jet' is more likely to be an inclined spiral galaxy se en in projection against the BL Lac object, or a nearby companion gala xy. We also present evidence that 1E 1415.6 + 2557 resides in a compac t group or a poor (Abel class 0) cluster of galaxies. These results ar e consistent with unification models in which BL Lac objects are low-l uminosity radio galaxies seen at a small angle to the line of sight of a relativistic jet.