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We report the first results from a survey for 1665, 1667, and 1720 MHz OHemission over a small region of the Outer Galaxy centered at $l \approx105.0\deg , b \approx +1.0\deg$ . This sparse, high-sensitivity survey ($\DeltaTa \approx \Delta Tmb \approx 3.0 - 3.5$ mK rms in 0.55 km/s channels), wascarried out as a pilot project with the Green Bank Telescope (GBT, FWHM$\approx 7.6'$) on a 3 X 9 grid at $0.5\deg$ spacing. The pointings chosencorrespond with those of the existing $^{12}$CO(1-0) CfA survey of the Galaxy(FWHM $\approx 8.4'$). With 2-hr integrations, 1667 MHz OH emission wasdetected with the GBT at $\gtrsim 21$ of the 27 survey positions ($\geq 78\%$), confirming the ubiquity of molecular gas in the ISM as traced by thisspectral line. With few exceptions, the main OH lines at 1665 and 1667 MHzappear in the ratio of 5:9 characteristic of LTE at our sensitivity levels. NoOH absorption features are recorded in the area of the present survey, inagreement with the low levels of continuum background emission in thisdirection. At each pointing the OH emission appears in several componentsextending over a range of radial velocity and coinciding with well-knownfeatures of Galactic structure such as the Local Arm and the Perseus Arm. Incontrast, little CO emission is seen in the survey area; less than half of the$\gtrsim 50$ identified OH components show detectable CO at the CfA sensitivitylevels, and these are generally faint. There are no CO profiles without OHemission. With few exceptions, peaks in the OH profiles coincide with peaks inthe GBT HI spectra (obtained concurrently, FWHM $8.9'$), although the converseis not true. We conclude that main-line OH emission is a promising tracer forthe "dark molecular gas" in the Galaxy discovered earlier in Far-IR andgamma-ray emission. Further work is needed to establish the quantitativedetails of this connection.

The Structure of Dark Molecular Gas in the Galaxy - I: A Pilot Survey for 18-cm OH Emission Towards $l \approx 105^{\deg}, b \approx +1^{\deg}$