Images of HCO+ (1-0) Emission in a Molecular Cloud near 1E1740.7-2942

We have observed the hard X-ray source 1E1740.7-2942 in the HCO+ (1-0) line using the Owens Valley millimeter interferometer. Previous single dish observations have found HCO+ emission coincident with the location of the radio continuum hot spots of the radio source associated with 1E1740.7-2942. Our higher resolution observations show a 15 arcsec offset between the HCO+ emission and the location of the radio hot spots. We propose that the lack of emission results from a large ionization rate, exceeding ${10}^{-15}$ s${}^{-1}$, in the neighborhood of 1E1740.7-2942.