VLA observations of the CND, which surrounds Sgr A West, and G359.1-0.5 have been carried out at the 1720 MHz transition of the OH molecule. 1720 MHz OH maser emission has been detected from the CND and G359.1-0.5 at velocities near V_LSR = +132 and -5 km/s, respectively. The OH maser features toward G359.1-0.5 have been detected along the interface between a large-scale non-thermal continuum shell G359.1-0.5 and its surrounding ring of high velocity molecular CO gas. The V spectra of a number of bright maser sources associated with the CND and G359.1-0.5 suggest strong magnetic fields between 0.4 and 4 mG. We argue that these masers are produced at the boundaries of G359.1-0.5 and the CND and that the maser features signify regions of shocked gas resulting from the supernova expansion and from cloud-cloud collisions at the Galactic center.
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