SiO maser survey in the Galactic center region with a multi-beam receiver

We have made a wide-field survey of SiO masers in the 7 ' x 13 ' area aroun d the Galactic center with the Nobeyama 45-m radio telescope using a 2 x 3 multi-beam SIS mixer receiver at 43 GHz. We detected 9 SiO maser sources (6 of them are new); newly detected 6 sources have not been identified with M iras or OH 1612 MHz maser sources. The source surface number density, simil ar to 360 per square degree, found in this survey is slightly smaller than the number density of OH 1612 MHz sources in the same area. A least-squares analysis of the radial velocities of the detected sources has revealed a r apid rotation of the stars around the Galactic center. This implies that mo st of the objects detected in this survey belong to the nuclear disk near t he Galactic center.