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Multiwavelength observations revealing the outbursts of the two soft X-ray transients XTE J1859+226 and XTE J1118+480

S. Chaty·C. A. Haswell·R. I. Hynes·C. R. Shrader·W. Cui·C. W. Mauche·A. J. Norton·J. -E. Solheim·R. Ostensen·T. R. Geballe·Z. Ioannou·A. R. King
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Abstract

We report here on multiwavelength observations of the two new soft X-ray transients (SXTs) XTE J1859+226 and XTE J1118+480, which we observed with HST/RXTE/UKIRT. For XTE J1118+480 we also used EUVE since it is located at a very high galactic latitude and suffers from very low extinction. The two sources exhibited very different behaviour. XTE J1859+226 seems quite normal and therefore a good object for testing the accretion mechanisms in place during the outbursts, XTE J1118+480 is much more unusual because it exhibits i) a low X-ray to optical ratio and ii) a strong non-thermal contribution in the radio to optical domain, which is likely to be due to synchrotron emission. We concentrate here on the near-infrared (NIR) and optical observations of these two systems.

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S. Chaty, C. A. Haswell, R. I. Hynes, C. R. Shrader, W. Cui, C. W. Mauche, A. J. Norton, J. -E. Solheim, R. Ostensen, T. R. Geballe, Z. Ioannou, A. R. King. 2001-02-06. Multiwavelength observations revealing the outbursts of the two soft X-ray transients XTE J1859+226 and XTE J1118+480. https://arxiv.org/abs/astro-ph/0102103

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