Broadband Observations of the New X-Ray Burster SAX J1747.0–2853 during the 1998 March Outburst

We report on our discovery and follow-up observations of the X-ray source SAX J1747.0-2853 detected in outburst on 1998 March 10 with the BeppoSAX Wide-Field Cameras in the energy range 2-28 keV. The source is located about 0.°5 off the Galactic nucleus. A total of 14 type I X-ray bursts were detected in spring of 1998, thus identifying the object as a likely low-mass X-ray binary harboring a weakly magnetized neutron star. Evidence for photospheric radius expansion is present in at least one of the observed bursts, leading to an estimate of the source distance of ~9 kpc. We performed a follow-up target of opportunity observation with the BeppoSAX narrow-field instruments on March 23 for a total elapsed time of 7.2 × 104 s. The source persistent luminosity was 2.6 × 1036 ergs s-1 in the 2-10 keV energy range. The broadband spectral data (1-200 keV) are consistent with a remarkable hard X-ray spectrum detected up to ~150 keV, highly absorbed at low energies (NH ≃ 1023 cm-2) and with clear evidence for an absorption edge at ~7 keV. A soft thermal component is also observed, which can be described by single-temperature blackbody emission at ~0.6 keV.