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IGR J01054-7253: a new INTEGRAL source discovered in the SMC

ATEL # 2079; E. Bozzo (ISDC,Geneva,Switzerland) C. Ferrigno (IAAT, Tuebingen, Germany & ISDC,Geneva,Switzerland) M.J Coe (University of Southampton, UK) P. den Hartog (HEPL/KIPAC/Stanford) A.J Bird (University of Southampton, UK), P. Lubinski (ISDC,Geneva,Switzerland) T. J. Maccarone (University of Southampton, UK) V. Beckmann (ISDC,Geneva,Switzerland) P. Ubertini (Iasf-Roma, Italy) K. Watanabe (Florida Gulf Coast University, USA)
on 12 Jun 2009; 9:38 UT
Distributed as an Instant Email Notice (Request for Observations)
Password Certification: Nami Mowlavi (

Subjects: X-ray, Gamma Ray, Request for Observations, Transients

We report on the detection of the new source IGR J01054-7253, with the IBIS/ISGRI detector aboard the INTEGRAL observatory, during the 47 Tucanae and SMC key program observation performed between 2009-06-07 05:26 and 2009-06-11 08:00 UTC (exposure time 124 ks).

The position of the source is Ra: 01:05:27 and Dec: -72:53:33 in the SMC. Since the detection significance in the 20-40 keV band is 7.3 sigma, the error on this position is 3.5' at 90% confidence level (Gros et al, 2003, A&A 411, L179L183).

The spectrum of the source, as measured by IBIS/ISGRI, is best fit by using a simple power law model with photon index 2.5+/-0.9. The flux in the 20-40 keV energy band is 1.8x10^(-11) ergs/cm^2/s (~3 mCrab). The source is also marginally detected by the JEM-X monitor at a significance of 4 sigma (3-10 keV energy band). The corresponding flux can be estimated in a few mCrab.

We notice that the position of this object is coincident, within the errors, with the ROSAT source RX J0104.7-7253 (Kahabka P. et al., 1999, A&AS, 136, 81), whose count rate in the 0.1-2.4 keV band was (1.36+-0.41)x10^(-3). By assuming a power law spectrum with a photon index of 2 and a Galactic absorption column density of 5x10^(20) cm^(-2), such a count rate corresponds to an X-ray flux of 3x10^(-14) erg/cm^2/sec.

Although the IBIS/ISGRI and ROSAT energy bands are very different, this result suggests that either the ROSAT source is not the counter part of IGR J01054-7253, or that this source is indeed strongly variable.

Swift follow-up observations of this source have already been requested.

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R. E. Rutledge , Editor
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