AAS 203rd Meeting, January 2004
Session 81 Black Holes
Poster, Wednesday, January 7, 2004, 9:20am-6:30pm, Grand Hall

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[81.08] Monitoring the Spectral Variability of the Ultraluminous X-Ray Source in Holmberg IX

B.E. Unks, P.O. Slane, K.A. Erikson, A.H. Szentgyorgyi, P. Kaaret (CXC)

We present Chandra observations of 1E0953.8+6918, an Ultra-Luminous X-ray source (ULX) associated with Holmberg IX. This source is of particular interest for both its position in a region devoid of star formation and its association with a large (250 pc) shock heated nebula. Three 15ks exposures observed approximately three months apart were obtained using the ACIS in continuous clocking (CC) mode. This type of observation provides excellent spectral data alongside rapid cadence timing. The three observations provided data from 1E0953.8+6918 covering 25% and 60% relative changes in luminosity. We observe that the spectral shape is largely independent of luminosity over this range. In addition, we discuss a search for Quasi-Periodic oscillations (QPOs) aimed at providing constraints on the mass of the system. This work is supported in part by NASA Contract NAS8-03060 and Chandra grant GO3-4035X.

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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.