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The exquisite angular resolution available with Chandra should allowprecision measurements of faint diffuse emission surrounding bright sources,such as the X-ray scattering halos created by interstellar dust. However, theACIS CCDs suffer from pileup when observing bright sources, and this createsdifficulties when trying to extract the scattered halo near the source. Theinitial study of the X-ray halo around GX13+1 using only the ACIS-I detectordone by Smith, Edgar & Shafer (2002) suffered from a lack of sensitivity within50'' of the source, limiting what conclusions could be drawn.  To address this problem, observations of GX13+1 were obtained with theChandra HRC-I and simultaneously with the RXTE PCA. Combined with the existingACIS-I data, this allowed measurements of the X-ray halo between 2-1000''.After considering a range of dust models, each assumed to be smoothlydistributed with or without a dense cloud along the line of sight, the resultsshow that there is no evidence in this data for a dense cloud near the source,as suggested by Xiang et al. (2005). Finally, although no model leads toformally acceptable results, the Weingartner & Draine (2001) and nearly all ofthe composite grain models from Zubko, Dwek & Arendt (2004) give poor fits.

X-ray Dust Scattering at Small Angles: The Complete Halo around GX13+1