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ATEL # 1018; J.A. Tomsick (SSL/UC Berkeley and CASS/UC San Diego), S. Chaty (AIM CEA Saclay/University Paris 7), J. Rodriguez (AIM CEA Saclay), R. Walter (ISDC)
on 1 Mar 2007; 21:42 UT
Password Certification: John A. Tomsick (firstname.lastname@example.org)
Subjects: Infra-Red, X-ray, Binaries, Black Holes, Neutron Stars
IGR J09026-4812 is a hard X-ray source that is within 1.1 degrees of the Galactic plane (Bird et al. 2006, 2007). To date, no optical/IR counterpart has been suggested for this source, and its nature is uncertain. In order to localize the X-ray source and determine its counterpart, we obtained a 5 ks observation with the Chandra X-ray Observatory on 2007 February 5. The 0.3-10 keV Chandra image shows only one bright source in the INTEGRAL error circle at a position of R.A. = 09h 02m 37s.29, Decl. = -48d 13' 34".2 (equinox 2000.0, 90% confidence uncertainty = 0".6). The Chandra spectral analysis is somewhat complicated by instrumental pile-up, but a fit to the spectrum with an absorbed power-law model (with pile-up correction) leads to a flux measurement of 5 x 10^-12 ergs/cm^2/s (0.3-10 keV, absorbed). Preliminary parameter values are a column density of N_H = (2.2+/-0.5) x 10^22 cm^-2 and a photon index of 2.7+/-0.6 (90% confidence errors). Although the spectrum does not appear to be as hard as has been obtained with Chandra for some other IGR sources (see, e.g., Tomsick et al. 2006, ApJ, 647, 1309 and ATEL#959), it is still very likely that the Chandra and INTEGRAL sources are the same. 2MASS J09023731-4813339 lies 0".4 from the Chandra position and is the likely IR counterpart. The 2MASS source has IR magnitudes of J = 15.57+/-0.08, H = 13.86+/-0.07, and K = 12.69+/-0.04. While IR or optical spectroscopy is required to determine the nature of this source, the bright candidate IR counterpart suggests a possible High-Mass X-ray Binary nature for IGR J09026-4812.