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Improved X-ray position for unidentified/unclassified INTEGRAL sources in the 4th IBIS survey

ATEL # 2441; J.B. Stephen, R. Landi, N. Masetti (INAF/IASF Bologna), M. Fiocchi, F. Capitanio (INAF/IASF Roma), A.J. Bird, D.J. Clark (Univ. Southampton)
on 16 Feb 2010; 16:14 UT
Password Certification: Raffaella Landi (

Subjects: X-ray, Gamma Ray, Request for Observations
Referred to by ATEL #: 2445

We provide improved X-ray positions for a few of the still unidentified/unclassified INTEGRAL sources reported in the 4th IBIS survey (Bird et al. 2010, ApJS, 186, 1). These X-ray associations were found by cross-correlating the IBIS catalogue with 3 X-ray databases currently present in the HEASARC archive and obtained from data collected by the ROSAT (Bright and Faint Source Catalogues or RASSBSC [Voges et al. 1999, A&A, 349, 389] and RASSFSC [Voges et al. 2000, available at] respectively) and XMM-Newton (XMM Slew catalogue, Saxton et al. 2008, A&A, 480, 611) satellites. Using the cross-correlation method developed by Stephen et al. (2005, A&A, 432, L49), we find for each catalogue a strong correlation with a small number of associations expected by chance. Among the associations, 9 objects are in the list of unidentified/unclassified IBIS sources and are listed below where we provide coordinates and error radius of the X-ray counterpart, its distance from the INTEGRAL source position, the X-ray catalogue used and information on the counterpart if available.

All but 3 objects are located more than 10 degrees from the Galactic plane which suggests an extragalactic origin for most sources. 1RXS J175252.0-053210 has a radio counterpart, while 1RXS J090320.0+533022 is a galaxy detected in the SDSS survey (Abazajian et al. 2009, ApJS, 175, 297) and so both are likely active galactic nuclei. IGR J18538-0102 is spatially coincident with a hot spot in the supernova remnant candidate G32.1-0.9 detected in X-rays by ROSAT (Folgheraiter et al. 1997, MNRAS, 292, 365): it has a much harder spectrum and higher absorption than observed in the supernova remnant. This suggests the possibility that IGR J18538-0102 could be a more distant Galactic source or a background AGN and its alignment with G32.1-0.9 is only coincidental. Finally, IGR J17488-2338 is associated with a bright radio source with a double lobe morphology having the X-ray emission centered on the nucleus (see the image available at the link reported at the bottom of this ATel): thus the counterpart of this INTEGRAL source is a new active radio galaxy detected behind the Galactic plane. The nature of the remaining 5 objects cannot be determined at the moment either because there are too many optical/infrared counterparts in the USNO B-1.0 (Monet et al. 2003, AJ, 125, 984) and/or 2MASS catalogues (Skrutskie et al. 2006, AJ, 131, 1163) or none at all. Follow-up observations with optical and infrared telescopes of the likely counterparts of these INTEGRAL sources are strongly encouraged.

           Name                ROSAT coordinates       X-ray radius   Distance    Catalogue         Counterpart                             RA(J2000)  Dec{J2000)      (arcsec)      (arcmin)     

IGR J03502-2605 03 50 17.0 -26 04 43.5 25.0 1.40 RASSFSC None 1RXS J090320.0+533022 09 03 20.0 +53 30 22.0 14.0 0.83 RASSFSC SDSS J090320.76+533029.5 IGR J09453-2600 09 45 18.4 -26 02 57.0 3.6 2.79 XMM Slew None IGR J15409-4057 15 41 02.1 -40 58 04.0 31.0 1.47 RASSFSC Multiple IGR J17488-2338* 17 48 38.9 -23 35 26.8 5.1 3.28 XMM Slew PMN J1748-2335 1RXS J175252.0-053210 17 52 52.0 -05 32 10.0 11.0 0.80 RASSBSC NVSS J175252-053212 IGR J18482+0049* 18 48 14.3 +00 47 48.8 4.5 2.17 XMM Slew None IGR J18538-0102* 18 53 48.2 -01 02 26.4 3.0 0.63 XMM Slew FWW97 A IGR J19475+0049 19 47 29.1 +00 49 45.0 14.0 0.10 RASSFSC Multiple

* Sources located within +/-10 degrees from the Galactic plane

NVSS image of the region surrounding IGR J17488-2338

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