Two New and Remarkable Sightlines through the Galactic Center's
  Molecular Gas
  Until now the known sources in the Galactic center with sufficiently smooth
spectra and of sufficient brightness to be suitable for high resolution
infrared absorption spectroscopy of interstellar gas occupied a narrow range of
longitudes, from the central cluster of hot stars to approximately 30 pc east
of the center. In order to more fully characterize the gas within the r ~ 180
pc central molecular zone it is necessary to find additional such sources that
cover a much wider longitudinal range. We are in the process of identifying
luminous dust-embedded objects suitable for spectroscopy within 1.2 deg in
longitude and 0.1 deg in latitude of Sgr A* using the Spitzer GLIMPSE and the
2MASS catalogues. Here we present spectra of H3+ and CO towards two such
objects, one located 140 pc west of Sgr A*, and the other located on a line of
sight to the Sgr B molecular cloud complex 85 pc to the east of Sgr A*. The
sightline to the west passes through two dense clouds of unusually high
negative velocities and also appears to sample a portion of the expanding
molecular ring. The spectra toward Sgr B reveal at least ten absorption
components covering over 200 km/s and by far the largest equivalent width ever
observed in an interstellar H3+line; they appear to provide the first
near-infrared view into that hotbed of star formation.
