High-resolution CH observations of two translucent molecular clouds

We present high-resolution (1′.3 × 1′.6) observations of the CH ²Π_1/2 (F = 1-1) emission line at 3335MHz in two high-latitude translucent clouds, MBM 3 and 40. At the assumed cloud distances, the angular resolution corresponds to ∼0.05pc, nearly an order of magnitude better than previous studies. Comparisons of the CH emission with previously obtained CO(1-0) data are difficult to interpret: the CO and CH line emission correlates in MBM 40 but not in MBM 3. In both clouds, there is a spatial offset in the peak emission, and perhaps in velocity for MBM 40. The difference in emission characteristics for the two tracers are noticeable in these two nearby clouds because of the high spatial resolution. Since both CH and CO are deemed to be reliable tracers of H₂, our results indicate that more care should be taken when using one of these tracers to determine the mass of a nearby molecular cloud.