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M. D. Audley, F. Nagase, K. Mitsuda (ISAS), L. Angelini (USRA / GSFC), R. L. Kelley (NASA / GSFC)
We report on two ASCA observations of the high-mass X-ray binary pulsar OAO~1657-415. A short observation near mid-eclipse caught the source in a low-intensity state. A later, longer observation of the source in its high state covered the eclipse ingress through mid-eclipse.
In the second observation we found that the eclipse continuum emission was dominated by a soft, spatially extended component whose intensity decreased through the eclipse. We interpret this component as a dust-scattered X-ray halo. We constructed surface brightness profiles from the ASCA SIS data and fit a simple model halo convolved with the telescope's point spread function. We thus extracted the energy and time dependence of the halo and used the results to place constraints on the nature of the interstellar dust and the distance to the source.
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The author(s) of this abstract have provided an email address for comments about the abstract: audley@iname.com