Program: GN-2011B-Q-12

We request poor weather time to continue our search for bright objects with featureless infrared spectra on sightlines to the Galactic center. Such objects are needed in order to more thoroughly study the interstellar environment toward and within the GC. Our previous research has used high resolution spectroscopy of H3+ and CO toward known sources in the central few tens of parsecs of the Galaxy to identify a previously unknown but apparently extensive component of the interstellar environment there, warm and diffuse gas. Evidence to date suggests that this component pervades the central molecular zone (CMZ), which extends ~170 pc from the center, but it is necessary to identify additional smooth-spectrum sources further from the center to use as probes to determine its true extent and better characterize the gas. Using Gemini in previous semesters to observe candidate sources identified from 2MASS and GLIMPSE photometry, we have already found several such sources and have already obtained several striking high-resolution spectra. The requested time would allow us to survey 45 more candidate objects mostly from our 2011A program that was awarded Band 3 time, but is unlikely to be completed. Our target list can be enlarged if needed.