A survey of the Galactic center region in HCO+, H13CO+, and SiO D. Riquelme, L. Bronfman, R. Mauersberger, J. May and T. L. Wilson A&A, 523 (2010) A45 Published online: 16 November 2010 DOI: 10.1051/0004-6361/200913359