KS 1730-312

K. Borozdin, N. Alexandrovich, V. Arefiev and R. Sunyaev, Space Research Institute, Moscow, on behalf of the MIR-KVANT-TTM team, communicate: "During observations of the Galactic Center field by the TTM coded-mask instrument onboard the MIR space station on Sept. 23, a flux of 70 +/- 10 mCrab within the energy band 2-30 keV was detected from R.A. = 17h30m.3, Decl. = -31d11' (equinox 1950.0, uncertainty +/- 2'). The source spectrum can be approximated by a power law with spectral index -1.9 +/- 0.4." E. Churazov, M. Gilfanov, J. Ballet and E. Jourdain, on behalf of the Granat Team (Space Research Institute, Moscow; Service d'Astrophysique, Centre d'Etudes de Saclay; and Centre d'Etude Spatiale des Rayonnements, Toulouse), report: "During observations of the Galactic Center region on Sept. 22-23 the SIGMA telescope onboard Granat Observatory detected a new hard x-ray source that is compatible with the above position. The 40-150-keV flux from the source was about 130 mCrab. No significant emission from this source has been detected by SIGMA in previous observations, performed during Sept. 1-22 with 3-sigma upper limits of 40 mCrab (Sept. 20-22) and 15 mCrab (Sept. 1-22). In subsequent observations on Sept. 24-25 and 25-26 the source flux was 116 and 93 mCrab, respectively. Gradual softening of the spectrum has been observed with the power-law photon index changing from 2.2 +/- 0.2 on Sept. 22-23 to 2.9 +/- 0.5 on Sept. 25-26."