MS-0205.7- A MICROLENSED BL LACERTAE CANDIDATE(3509 )

In the course of an extensive, deep imaging survey of BL Lacertae obje cts made at the Canada-France-Hawaii 3.6 m Telescope (CFHT), the BL La c object MS 0205.7+3509 was found to be significantly decentered (simi lar to 1'') with respect to its ''host'' galaxy. In addition, this hos t is a spiral and, at a tentative z = 0.318, is significantly underlum inous with respect to typical BL Lac object hosts. The ROSAT PSPC soft X-ray spectrum shows evidence for an absorbing column well in excess of Galactic at log N-H = 21.2 +/- 0.1. Taken together, this evidence s uggests but does not conclusively prove that this BL Lac object is bac kground to the spiral through which it is viewed. But no multiple imag es are found at radio or optical wavelengths suggesting that the foreg round galaxy has a very large core radius and/or low surface brightnes s. Since this makes the fourth such BL Lac object with these general c haracteristics, a gravitational lensing scenario which creates the obs ervable features of a BL Lac object through microlensing of a backgrou nd quasar without creating multiple images should be investigated theo retically in some detail.