High resolution mapping of galactic H I in the direction of 3C147

In the present high resolution H I emission and absorption data for the field of 3C147, the H I brightness temperature distribution is clumpy and the absorption features are identifiable with 3-6 arcmin features whose brightness temperatures lie in the 4-10 K range. The clumps have excitation temperatures in the 34-74 K range, with H I masses between 0.03 and 0.5 solar masses (assuming a distance of 500 pc). The clumps of absorbing H I gas are associated with extended warm halos which dominate the observed H I emission. The fact that the absorbing gas is concentrated in small scale clumps severely constrains the interpretation of available apparent spin temperatures, since they are not direct indicators of the excitation temperature of the H I gas.