An ultrasoft transient X-ray source near the Galactic bulge region

Further analysis of an ultrasoft transient X-ray source near the Galactic bulge region is reported. This source was discovered in scanning observations with Ginga, and was at first designated as GS 1734-275 (Makino 1988). The source position was re-determined using revised satellite attitude data, and then this source was named GS 1732-273. The revised position is in agreement with those of the transient sources, KS 1732-273, discovered with Mir-Kvant in 1989, and 1RXS J173602.0-272541, discovered with the ROSAT all-sky survey in 1990. The X-ray spectrum, constructed by a scan-fit technique, is well represented by a multicolor disk model with a temperature at the inner disk radius of 0.7-0.8 keV. The spectral properties and the transient behavior suggest that GS 1732-273 is a candidate source of black hole binaries.