GX 340-0 Region

R. Sunyaev, M. Gilfanov, A. Goldurm and M. C. Schmitz-Fraysse, on behalf of the Granat team (Space Research Institute, Moscow; Centre d'Etude Spatale des Rayonnements, Toulouse; Service d'Astrophysique du CEA, Saclay), report: "Observations of the GX 340-0 (Ara X-1) field were performed with GRANAT on Aug. 21-22. GX 340-0 itself was detected by the ART-P telescope at a level of 220 mCrab in the 4-20 keV band, and the 3-sigma upper limit in the 40-92 keV band was 30 mCrab (SIGMA data). GX 339-4 was detected by SIGMA in a very bright state, about 320 mCrab in the 40-150 keV band, confirming the BATSE results on IAUC 5327; this source was detected up to about 200 keV with a power-law photon index of about 2.1 and flux about 1.9E-4 photon s-1 cm-2 keV-1 at 100 keV. The pulsar OAO 1657-415, also detected by SIGMA, gave barycentric P = 37.6726 +/- 0.0015 s, indicating further spin-up since an ART-P observation on Feb. 18 gave P = 37.7897 +/- 0.0003 s. 4U 1700-37 was detected close to the edge of the SIGMA field of view at a level of 190 mCrab in the 40-150 keV band. Further GRANAT observations on Aug. 29-30 show that GX 339-4 continues to be in bright state with 30-150 keV flux about 330 mCrab. GRANAT observations of the region are also scheduled on Sept. 2, 6 and 25."