Discovery of the X-ray transient SAX J1808.4-3658, a likely low mass X-ray binary

Zand, J. J. M. in 't; Heise, J.; Muller, J. M.; Bazzano, A.; Cocchi, M.; Natalucci, L.; Ubertini, P.

Discovery of the X-ray transient SAX J1808.4-3658, a likely low mass X-ray binary

Authors

Description

We report the discovery of a fairly bright transient during observations with the Wide Field Cameras on board the BeppoSAX satellite in September 1996. It was detected at a peak intensity of 0.1 Crab (2 to 10 keV) and lasted between 6 and 40 days above a detection threshold of 2 mCrab. Two very bright type I X-ray bursts were detected from this transient in the same observations. These almost certainly identify this X-ray transient as a low-mass X-ray binary with a neutron star as compact component. The double-peaked time history of both bursts at high energies suggests a peak luminosity close to the Eddington limit. Assuming this to be true implies a distance to this object of 4 kpc.
4 pages, 4 figures, published in A&A March II 1998 issue