  To understand the environment and extended structure of the host galactic gas
whose molecular absorption line chemistry, we previously observed along the
microscopic line of sight to the blazar/radiocontinuum source NRAO150 (aka
B0355+508), we used the IRAM 30m Telescope and Plateau de Bure Interferometer
to make two series of images of the host gas: i) 22.5 arcsec resolution
single-dish maps of 12CO J=1-0 and 2-1 emission over a 220 arcsec by 220 arcsec
field; ii) a hybrid (interferometer+singledish) aperture synthesis mosaic of
12CO J=1-0 emission at 5.8 arcsec resolution over a 90 arcsec-diameter region.
CO components that are observed in absorption at a moderate optical depth (0.5)
and are undetected in emission at 1 arcmin resolution toward NRAO 150 remain
undetected at 6 arcsec resolution. This implies that they are not a
previously-hidden large-scale molecular component revealed in absorption, but
they do highlight the robustness of the chemistry into regions where the
density and column density are too low to produce much rotational excitation,
even in CO. Bright CO lines around NRAO150 most probably reflect the variation
of a chemical process, i.e. the C+-CO conversion. However, the ultimate cause
of the variations of this chemical process in such a limited field of view
remains uncertain.
