Abstract
We report a phase-resolved spectral analysis of the anomalous X-ray pulsar RX J170849-400910 using archival data of a BeppoSAX observation conducted on 1999 March 31 -- April 1. Models of a power-law plus one blackbody and a power-law plus two-blackbodies both fit the spectra very well, but most of the flux is attributed to the nonthermal component for the former and to the thermal one for the latter. Photon power indices, blackbody temperatures, and estimated thermal and nonthermal fluxes all vary with phase. The necessity of invoking a power-law component in spectral fitting, even in the case that most of the flux is thermal, poses severe challenges to those models involving only surface thermal emission as the nature of the radiation from anomalous X-ray pulsars.