2003IAUC.8050....1R

R. A. Remillard, A. M. Levine, and E. H. Morgan, Massachusetts Institute of Technology (MIT); and E. Smith and J. Swank, Goddard Space Flight Center (GSFC), for the RXTE All Sky Monitor Team at MIT and NASA's GSFC, report the discovery of a transient x-ray source at R.A. = 17h19m58s, Decl. = -31o46'.8 (equinox 2000.0; estimated 3' uncertainty at 90-percent confidence): "The source was first detected on 2003 Jan. 9, when the average flux (2-12 keV) was 130 ± 20 mCrab. The intensity increased to 430 ± 40 mCrab on Jan. 10, and to 400 ± 20 mCrab on Jan. 13. A brief observation of the ASM position on Jan. 14 with the RXTE PCA confirms the presence of a bright transient. More extensive observations with the PCA and HEXTE, including raster scans to improve the source position, are planned starting Jan. 15. The error circle does not contain any noteworthy sources in the Simbad catalogs. The ASM hardness ratios indicate that the spectrum was moderately hard during Jan. 9-10 and relatively soft on Jan. 13. These results resemble the early spectral evolution of x-ray transients known to contain an accreting black hole. We encourage optical and radio observations of this new transient."