BeppoSAX spectroscopy of the globular cluster X-ray source XB 1746-371 (NGC 6441)

During a BeppoSAX observation of the X-ray source XB 1746-371 located in th e globular cluster NGC 6441 a type I X-ray burst, parts of 4 intensity dips , and energy dependent flaring were detected. The dips repeat every 5.8+/-( 0.3)(0.9) hr and show no obvious energy dependence. If the dips are due to electron scattering this energy independence implies an abundance > 130 tim es less than solar, confirming an earlier measurement. Since the overall cl uster abundance is close to solar this low abundance is unexpected. Photoio nization of the absorbing material, obscuration of an extended source, and variations in multiple components that combine to produce an apparent energ y independence are all excluded. Thus, the nature of the dips remains uncer tain. The best-fit model to the overall 0.3-30 keV spectrum is a disk-black body with a temperature of 2.82 +/- 0.04 keV, together with a cutoff power- law with a photon index of -0.32 +/- 0.80 and a cutoff energy of 0.90 +/- 0 .26 keV. Absorption, consistent with the optical extinction to NGC 6441 of (0.28 +/- 0.04) x 10(22) atom cm(-2) is required. All:previous best-fit spe ctral models for this source are excluded at high confidence. The spectrum is dominated by the blackbody-like component, with the cutoff power-law onl y contributing an average of 12% of the 1-10 keV flux. During flaring inter vals the contribution of this component decreases to similar to 6% with var iations in the intensity of the blackbody-like component being responsible for most of the flaring activity.