FAINT EXTENDED OH EMISSION FROM THE LOCAL INTERSTELLAR MEDIUM IN THE DIRECTIONl≈ 108°,b≈ 5°

We have mapped faint 1667 OH line emission ( T A ≈ 20–40 mK in our ≈30' beam) along many lines of sight in the Galaxy covering an area of ≈4° × 4° in the general direction of l ≈ 108°, b ≈ 5°. The OH emission is widespread, similar in extent to the local H i ( r ≲ 2 kpc) both in space and in velocity. The OH profile amplitudes show a good general correlation with those of H i in spectral channels of ≈1 km s −1 ; this relation is described by T A (OH) ≈1.50 × 10 −4 T B (H i ) for values of T B (H i ) ≲ 60–70 K. Beyond this the H i line appears to "saturate," and few values are recorded above ≈90 K. However, the OH brightness continues to rise, by a further factor ≈3. The OH velocity profiles show multiple features with widths typically 2–3 km s −1 , but less than 10% of these features are associated with CO(1–0) emission in existing surveys of the area smoothed to comparable resolution.