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Swift/XRT observation of the on-going outburst from Terzan 6

ATel #10835; E. Bozzo (ISDC, Switzerland), A. Sanna (Univ. Cagliari, Italy)
on 10 Oct 2017; 16:34 UT
Credential Certification: E. Bozzo (enrico.bozzo@unige.ch)

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

Following the discovery of an on-going outburst from the direction of the Globular Cluster Terzan 6 (ATel #10832), a Swift/XRT ToO in PC mode has been requested in order to improve the X-ray position and confirm the possibility that the new outburst is from the known low mass X-ray binary GRS 1747-312.

Swift/XRT observed the field around the Globular Cluster Terzan 6 on 2017-10-09 at 14:02 for a total exposure time of 1 ks. The best determined position provided by the on-line tool (Evans et al. 2009, MNRAS, 397, 1177) for the far brightest source within the instrument field of view (and likely counterpart of the INTEGRAL source) is at RA=267.69505 DEC=-31.27512 (J2000), with an associated uncertainty of 2.2 arcsec. This position is consistent with the best known location of GRS 1747-312 (in't Zand et al. 2003, A&A, 406, 233).

The Swift/XRT spectrum could be reasonably well described by using a power-law of photon index 1.3+/-0.2. The measured absorption column density is of 2.5(+0.5,-0.4)E22 cm^-2 and the estimated 0.3-10 keV flux from the spectral fit is 1E-10 erg/cm^2/s. No thermonuclear bursts have been detected during the relatively short XRT pointing.

Multi-wavelength observations are encouraged.

We are grateful to the Swift planning team for the extremely rapidly scheduling of the XRT ToO observation.