Swift X-ray follow-up observations of two INTEGRAL sources: IGRJ12470-5407 and IGRJ18532+0416

ATel #3256; M. Fiocchi (INAF IASF/Roma), R. Landi(INAF IASF/Bologna), L. Bassani(INAF IASF/Bologna), A. Bazzano (INAF IASF/Rome), A. J. Bird (University of Southampton, UK), Gehrels (NASA/GSFC), J. A. Kennea (PSU)
on 4 Apr 2011; 14:59 UT
Credential Certification: mariateresa fiocchi (mariateresa.fiocchi@iasf-roma.inaf.it)

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We report the results of X-ray follow-up observations performed with Swift/XRT of two unidentified INTEGRAL sources, IGRJ12470-5407 and IGRJ18532+0416, listed in the 4th IBIS Survey Catalogue (Bird et al. 2010, ApJS, 186, 1).

IGRJ12470-5407 This source is a very weak IBIS unidentified object with a flux < 0.3 mCrab in the 20-40 keV energy band ( Bird et al. 2010, ApJS, 186, 1).
The field of this source was observed with Swift-XRT on 2011-02-17 03:33:01 and 2011-02-19 18:06:01, for a total exposure time of 4312 s.
Within the 99% IBIS positional uncertainty we found only one XRT source above 3 sigma c.l., located at R.A.(J2000) = 12h 47m 50.80s and Dec.(J2000) = -54d 06m 30.80s with an uncertainty of 5 arcsec. The XRT object was detected at 5.0 sigma and 3.3 sigma c.l. in the energy range 0.3-10 keV and 3-10 keV, with a corresponding flux of 8x10^-13 erg s^-2cm^-2 and 7x10^-13 erg s^-1 cm^-2, respectively.
No counterparts were found when searching the archives in other energy bands.

IGRJ18532+0416 This source is a weak and persistent IBIS unidentified object with a flux of ~0.3 mCrab and ~0.6 mCrab in the 20-40 keV and 40-100 keV energy band, respectively ( Bird et al. 2010, ApJS, 186, 1).
The field of this source was observed by Swift-XRT on 2011-02-19 03:45:01 for a exposure time of 3786 s.
Within the IBIS error circle at 99% c.l., two objects are detected above 3 sigma c.l.:
Source #1, detected at 3.4 sigma c.l. (0.3-10 keV), is located at R.A.(J2000) =18h 53m 12.3s and Dec.(J2000) = +04d 13m 27.2s with a uncertainty of 6 arcsec (90%c.l.).
Source #2 is detected at 4.4 sigma c.l.(0.3-10 keV) and its position is at R.A.(J2000) = 18h 53m 16.3s and Dec.(J2000) = +04d 17m 50.6s with a uncertainty of 5 arcsec (90%c.l.).
Source #2 is a highly likely counterpart of the IBIS object because it is the only object detected (at 3 sigma c.l..) in the XRT hard energy band 3-10 keV. The X-ray spectroscopy indicates that the source flux is ~6 x 10^-13 erg cm^-2 s^-1 and ~5 x 10^-13 erg cm^-2 s^-1 in the 0.3-10 keV and 3-10 keV energy band, respectively. This X-ray source has two possible IR counterparts in the 2MASS catalogue named 2MASS18531638+0417540 and 2MASS18531602+0417481 with magnitudes J ~16.5, H ~14.1 and K ~14.4 and J ~16.5, H ~14.1 and K ~13.9, respectively.