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Swift/XRT monitoring of the long outburst of the Very Faint X-ray Transient XMMU J174716.1-281048

ATEL # 2624; Melania Del Santo (INAF/IASF-Roma), Patrizia Romano (INAF/IASF-Palermo), Lara Sidoli (INAF/IASF-Milano)
on 18 May 2010; 13:25 UT
Password Certification: Melania Del Santo (

Subjects: X-ray, Binaries, Transients

The Very Faint X-ray Transient (VFXT) XMMU J174716.1-281048, discovered in 2003 by XMM-Newton (ATel #147 and Sidoli et al., 2006, A&A 456, 287), is a type I burster (ATel #970; #972; Del Santo et al., 2007, A&A 468, L17) lying in the Galactic Centre region (ATel #1207). XMMU J174716.1-281048 is the first source classified as ``quasi persistent" VFXT, because it is in outburst since 2003 (Del Santo et al., 2007, A&A 468, L17; ATel #1078). The level of its X-ray emission has been regularly monitored by Swift since May 2007 (ATel #1078, #1174, #1496, #2050).

A new ToO with Swift/XRT was performed on 2010 May 13 07:28:35 to 10:51:56 (1 ks net exposure), and on May 17 07:38:46 to 14:10:48 (3.7 ks net exposure). The source was found still in outburst with a mean 0.2-10 keV count rate of (2.3+/-0.4)E-02 counts/s. The XRT spectrum can be fitted with an absorbed power law with a photon index of 2.3 (-1.3, +1.5) and a column density, Nh, of 8 (-4, +6) E22 cm^-2 (cstat=61.2, dof=62). The 2-10 keV unabsorbed flux of 4E-12 erg/cm2/s translates into a luminosity of 3E34 erg/s (at 8 kpc).

The long-term light curve of XMMU J174716.1-281048 can be found at

We would like to thank the Swift Team for making these observations possible, in particular N. Gehrels, the duty scientists as well as the science planners.

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R. E. Rutledge , Editor
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