BeppoSAX observation of the eclipsing dipping X-ray binary X1658-298

Results of a 2000 August 12-13 BeppoSAX observation of the 7.1 hr eclipsing , dipping, bursting, transient, low-mass X-ray binary (LMXRB) X 1658-298 ar e presented. The spectrum outside of eclipses, dips and bursts can be model ed by the combination of a soft disk-blackbody and a harder Comptonized com ponent with a small amount (1.3 x 10(21) atom cm(-2)) of low-energy absorpt ion. In contrast, an RXTE observation 18 months earlier during the same out burst, measured an absorption of 5.0 x 10(22) atom cm(-2). Such a change is consistent with a thinning of the accretion disk as the outburst progresse s. Structured residuals from the best-fit spectral model are present which are tentatively identified with Ne-K/Fe-L and Fe-K shell emission. The spec tral changes during dips are complex and may be modeled by a strong (simila r to3 x 10(23) atom cm(-2)) increase in absorption of the Comptonized compo nent only, together with reductions in normalizations of both spectral comp onents. This behavior is in contrast to the "complex continuum" model for X -ray dip sources, where the softer blackbody component rapidly suffers stro ng absorption. It is however, similar to that found during recent XMM-Newto n observations of the eclipsing, dipping, LMXRB EXO0748-676. An updated orb ital ephemeris is provided which does not require a quadratic term, in cont rast to that of Wachter et al. (2000).