AAS 195th Meeting, January 2000
Session 126. Drizzling Down the Potential Well: Accreting Compact Objects II
Oral, Saturday, January 15, 2000, 2:00-3:30pm, Regency VII

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[126.02] RXTE Spectral Study of the New X-ray Transient XTE J1859+226

W. B. Focke, C. B. Markwardt (NASA's GSFC / U. Maryland), J. H. Swank (NASA's GSFC), R. E. Taam (Northwestern U.)

The transient galactic black hole candidate XTE J1859+226 was discovered by the RXTE All Sky Monitor (ASM) on 1999 October 9, within a day after its outburst began. Pointed observations with RXTE began on 1999 October 10.57, and continued at a rate of about twice per day.

Preliminary results of fits to PCA and HEXTE spectra for October 9--14 show that a simple absorbed powerlaw is insufficient to model the data. The fit is greatly improved by using an absorbed cutoff powerlaw with reflection. The photon index rose from 1.8 on October 9 to 3.2 on October 14. The cutoff energy started near 100~keV, dropped to 50~keV, then rose to an undetectable level between October 12.86 and October 13.11, potentially indicating a state change.

We will present spectral analysis of these and later data, along with comparison of the spectral and timing properties.

This work was funded by NASA.

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