Discovery of SWIFT J174429.9-274557 - a soft X-ray counterpart of the X-ray burster IGR J17445-2747

ATel #10272; I. A. Mereminskiy, S. A. Grebenev, R. A. Krivonos, I. V. Chelovekov, R. A. Sunyaev (Space Research Institute, Moscow)
on 17 Apr 2017; 08:14 UT
Credential Certification: Sergei Grebenev (sergei@hea.iki.rssi.ru)

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The SWIFT/XRT observations of the IGR J17445-2747 field, inspired by the recent identification of this source as an X-ray burster (ATel #10256) and carried out on April 16, 2017, at 18:00 UT (1.5 ks of exposure), revealed its soft X-ray counterpart at the position R.A. = 17h44m29.85s = 266.12439 deg; Decl. = -27:45:57.51 = -27.76598 deg (epoch 2000.0, accuracy 3.6 arcsec). It is inconsistent with the position of any previously found soft X-ray source in the field (Landi et al. ATel #1273; Tomsik et al. 2008; Malizia et al. 2010; Heinke et al. ATel #10265). In particular, it is inconsistent with the position of XMMSL1 J174429.4-274609 which was suggested earlier to be a counterpart of IGR J17445-2747 (Malizia et al. 2010). The XRT image of the field can be found at the URL-link below.

The source spectrum being approximated by an absorbed power law (the best fit photon index 2.2+/-0.4, NH =(4.9+/-0.9)x10²² cm^-2) gave an estimate for its flux 4.2x10^-11 erg/cm²/s in the 0.5-10 keV and 3.3x10^-11 erg/cm²/s in the 3-10 keV. Being approximated by an absorbed black body it gave kT = 1.05+/-0.10 keV, NH = (2.3+/-0.6)x10²² cm^-2 and the flux 3.5x10^-11 erg/cm²/s in the 0.5-10 keV band. These estimates are generally consistent with the persistent flux (5.7x10^-11 erg/cm²/s) measured from this source by INTEGRAL/JEM-X in the 3-10 keV band during the observations on April 7-11, 2017, when the type I X-ray burst was detected from this source.

We thank the Swift team for approving these ToO observations and encourage follow-up observations of this source at all wavelengths.

XRT finding chart for SWIFT J174429.9-274557 - a soft X-ray counterpart of the X-ray burster IGR J17445-2747