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Swift resumes X-ray monitoring observations of the Galactic center in 2017

ATel #10089; N. Degenaar (University of Amsterdam), R. Wijnands (University of Amsterdam), M. T. Reynolds (University of Michigan), J. M. Miller (University of Michigan), J. A. Kennea (Penn State University), on behalf of a larger collaboration
on 17 Feb 2017; 19:01 UT
Credential Certification: Nathalie Degenaar (degenaar@uva.nl)

Subjects: X-ray, Binary, Black Hole, Neutron Star, Transient

On 2017 February 2, Swift resumed its daily X-ray monitoring campaign of the Galactic center using the XRT (Degenaar et al. 2015, JHEA 7, 137; see link below). We report that there are currently no active X-ray transients within the ~20x20 arcmin region around Sgr A* that is covered by our campaign (down to a limiting luminosity of ~1E34 erg/s at a distance of 8 kpc for a single 1-ks exposure).

We note that the last X-ray transient that was active before the Sun-constrained window, the neutron star low-mass X-ray binary XMM J174457-2850.3 (ATel #9551), returned to quiescence between October 5 and 10 after a ~2-week long outburst. During this time the source reached a 2-10 keV peak luminosity of ~3E35 erg/s (assuming a distance of 6.5 kpc as inferred from thermonuclear burst analysis; Degenaar et al. 2014, ApJ 792, 109). This is similar to previous outbursts of this source, which never become brighter than ~1E36 erg/s.

Updates on the daily X-ray observations of the Galactic center are immediately posted at the Swift Sgr A* Monitoring Campaign Website.