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IGR J17511-3057: Swift follow-up and INTEGRAL JEM-X detection of a type-I X-ray burst

ATel #7288; E. Bozzo (ISDC, Switzerland), C. Sanchez-Fernandez (ESA/ESAC, Spain), A. Papitto (ICE CSIC-IEEC, Spain), C. Ferrigno (ISDC, Switzerland), E. Kuulkers, J. Kajava (ESA/ESAC, Spain)
on 25 Mar 2015; 16:46 UT
Credential Certification: E. Bozzo (enrico.bozzo@unige.ch)

Subjects: Neutron Star, Transient, Pulsar

Following the INTEGRAL discovery of a new outburst from the accreting millisecond X-ray pulsar IGR J17511-3057 (Atel #7275, #2198, #2215), a monitoring campaign with Swift/XRT has been initiated.

An XRT observation has been carried out in PC mode on 2015-03-25 in order to confirm the source position in the soft X-rays. The XRT data are heavily piled-up. The approximate source flux measured from the XRT/PC observation is ~6.3E-10 erg/cm^2^/s (0.3-10 keV). The best determined XRT position is at:
RA = 17 51 08.47
DEC = -30 57 36.7
(J2000), with an associated uncertainty of 3.6 arcsec at 90% c.l. (we used the online tool at http://www.swift.ac.uk/user_objects ; Evans et al. 2009, MNRAS, 397, 1177).

This is about 4.9'' away from the best known Chandra position of IGR J17511-3057 (associated uncertainty 0.6'' at 90% c.l.; Paizis et al. 2012, ApJ, 755, 52), and 4.5'' from its identified NIR counterpart (Atel #2216). The marginal off-set between the new XRT position and the previously improved ones could be due to the heavy pile-up of the XRT data. A refined analysis of the XRT data is on-going.

A 20 s-long type-I X-ray burst from this source was detected by the JEM-X telescope on-board INTEGRAL. The onset of the burst was 57105.10924 MJD. This further suggests that the source in outburst is the known burster accreting millisecond X-ray pulsar IGR J17511-3057.

We warmly thank the Swift team for the rapid scheduling of the XRT monitoring of IGR J17511-3057.
Simultaneous observations at other wavelengths are encouraged.