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ATEL # 1423; R. Landi, N. Masetti, V. Sguera (INAF/IASF Bologna), A. Bazzano, M. Fiocchi (IASF/INAF Rome), A.J. Bird, A.J. Dean (Univ. Southampton)
on 14 Mar 2008; 15:38 UT
Password Certification: Raffaella Landi (email@example.com)
Subjects: X-ray, Gamma Ray, Request for Observations
We report on the X-ray follow-up observation performed with Swift/XRT of the still unidentified INTEGRAL source IGR J18325-0756, first announced by Lutovinov et al. 2003 (Atel #154). The source is also listed in the catalogues of Bird et al. (2007, ApJS, 170, 175) and Krivonos et al. (2007,A&A, 475, 775). At energies above 20 keV, IGR J18325-0756 is likely a transient object. The XRT telescope pointed at the source region on 2005, November 7 for 10.5 ks. Within the IBIS error box, we find only one source detected with a confidence level of 9 sigma and located at RA(J2000) = 18h 32m 28.30s and Dec(J2000) = -07d 56m 40.4s (4.1 arcsec uncertainty). The XRT uncertainty contains only one object listed in the 2MASS catalogue (2MASS J18322828-0756420) with infrared magnitudes J = 16.4, H = 15.3 and K = 14.5. The X-ray data analysis provides a flat power law spectrum with photon index ~0.8 (absorption fixed to the Galactic value of 1.5 x 1022 cm-2) and a 2-10 keV flux of 2 x 10-12 erg cm-2 s-1. A steeper spectrum (Gamma ~1.8) can also fit the data but only with the absorption exceeding the Galactic value (1.5 x 1023 cm-2).