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Refined X-ray position and near-IR identification for IGR J16413-4046

ATel #3342; John A. Tomsick (SSL/UC Berkeley), Sylvain Chaty (AIM - Univ. Paris 7 and CEA Saclay), Arash Bodaghee (SSL/UC Berkeley), Jerome Rodriguez (CEA-SAp/Lab. AIM Saclay)
on 12 May 2011; 17:09 UT
Credential Certification: John A. Tomsick (jtomsick@ssl.berkeley.edu)

Subjects: Infra-Red, X-ray, Black Hole, Neutron Star

IGR J16413-4046 is a hard X-ray source first reported in the 4th IBIS/ISGRI catalog (Bird et al. 2010). Follow-up Swift/XRT observations found an X-ray source with a hard X-ray spectrum within the INTEGRAL error circle that was identified as the counterpart to the IGR source (Landi et al. 2010, ATEL#2731; Landi et al. 2011, ATEL#3178).

As part of our Chandra program to localize sources discovered by INTEGRAL in the Galactic Plane, we obtained a 5.0 ks ACIS exposure of the IGR J16413-4046 field on UT 2011 May 9, 0.5-2.3 h. The brightest Chandra source in the field is CXOU J164119.4-404737, which has a position that is consistent with the position of the Swift source. The exact Chandra position of this source is R.A. = 16h 41m 19s.49, Decl. = -40d 47' 37".8 (equinox 2000.0, 90% confidence uncertainty = 0".64). This is consistent with the position of 2MASS J16411948-4047378, which has near-IR magnitudes of H = 15.08 +/- 0.11 and Ks = 13.97 +/- 0.07. This source is not present in the DENIS near-IR/optical or USNO optical catalogs. Also, we note that 2MASS J16411948-4047378 is not the 2MASS source that was originally suggested to be the near-IR counterpart in ATEL#2731. That source, 2MASS J16411927-4047323, is 6" from the Chandra position and, thus, is not the counterpart.

We plan to present a more detailed analysis of the Chandra data in a forthcoming paper. We encourage follow-up near-IR and optical observations of the source to determine its nature.