HIGH-RESOLUTION (CO)-C-13 AND (CO)-O-18 J=1-0 OBSERVATIONS OF NGC-1068 - MOLECULAR GAS PROPERTIES AND A HIGH (CO)-O-18 (CO)-C-13 INTENSITY RATIO/

We present high-resolution (similar to 5 ''-6 '') aperture synthesis o bservations of (CO)-C-13 and (CO)-O-18 J = 1-0 lines in the prototypic al Seyfert 2 galaxy NGC 1068. The line ratio S-v((CO)-C-12)/S-v((CO)-C -13) varies significantly along the ring, indicating optical depth var iations. We also find a high average line ratio [R] = [S-v((CO)-O-18)/ S-v((CO)-C-13)] = 0.3, which is almost twice the highest value in our own galaxy. This is also one of the highest values reported to date fo r an extragalactic source and the first such measurement for Seyfert g alaxies. We argue that such a high value could be the result of optica l depth effects and/or an intrinsically high [(CO)-O-18/(CO)-C-13] abu ndance.