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ATEL # 1002; M. A. P. Torres, D. Steeghs (CfA), P. G. Jonker (SRON/CfA), N. Morrell, M. Roth (LCO), W. L. Freedman (Carnegie)
on 14 Feb 2007; 5:46 UT
Password Certification: Manuel Torres (firstname.lastname@example.org)
Subjects: Infra-Red, X-ray, Binaries, Black Holes, Neutron Stars, Transients
We report follow-up observations confirming the near-infrared (NIR) counterpart to the X-ray transient and suggested black hole candidate IGR J17497-2821 (Soldi et al., ATel #885). A Ks=15.9 mag candidate was suggested in Torres et al. (ATel #909) on the basis of its coincidence with the Chandra localization for the X-ray source (Paizis et al. ATel #907; astro-ph/0611344). The candidate appeared blended with a brighter nearby NIR source to the east which partially overlaps the 0.6 arscec Chandra error circle.
Our observations consist of a series of Ks-band images obtained with the 6.5m Magellan Baade telescope between 2007 Feb 10 08:45-08:58 UT using the PANIC camera and totaling 450s on source. The frames were acquired with a seeing of 0.6 arcsec and the projected pixel size was 0.127 arcsec. Photometric and astrometric scales were defined with the same 2MASS references used in ATel #909.
Our images show that the proposed counterpart candidate has faded significantly and is no longer detected with a 3-sigma upper limit magnitude of Ks > 17.8. This limit is consistent with a late-type companion at a typical distance of the Galactic center.
This large decrease in brightness relative to the observations reported when the transient was in outburst confirms the candidate reported in ATEL #909 as the NIR counterpart to IGR J17497-2821.
Updated finding chart: