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P. Zhao, J.E. Grindlay, J. Hong, S. Laycock (Harvard-Smithsonian Center for Astrophysics), F.K. Baganoff, M.P. Muno (MIT), G.P. Garmire (Penn State), M. Morris (UCLA)
We present the initial optical counterpart identifications for the Chandra Catalog of X-ray sources towards the Galactic Center (Muno et al. ApJ submitted). 2357 X-ray point sources are detected during 590~ks of Chandra ACIS-I observations with a 17\primex17\prime field around SgrA*. The search for their optical counterparts is conducted with moderately deep V, R, I and H\alpha images covering the same field taken with the Mosaic camera on the CTIO 4-m telescope in March 2000 as part of the Chandra Multiwavelength Plane (ChaMPlane) Survey. The error radius of each Chandra source is estimated with a raytrace/wavdetect simulation based on the source off-axis angle and net counts. Some 237 sources are detected below 1.2~keV and with >99% source significance in the full 17\prime field. They are likely sources in the foreground of the Galactic Center. 204 of the 237 sources have matching optical counterparts. For the ~2000 sources detected in the hard band (2.5--8~keV), only ~10% have optical matching (at R<23). And most of these ~10% matches are likely coincident matches with foreground stars. We present our optical counterpart identification method used for the ChaMPlane Survey and the V, R, I, H\alpha magnitudes of the optical counterparts of this initial sample.
This work is supported by NASA/SAO grant AR1-2001X, AR2-3002A and NSF grant AST-0098683.
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Bulletin of the American Astronomical Society,
© 2003. The American Astronomical Soceity.