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Paper: New Optical Flux Limits for the Central X-ray Point Source in Cas A
Volume: 271, Neutron Stars in Supernova Remnants
Page: 305
Authors: Fesen, R. A.; Chevalier, R. A.; Holt, S. S.; Tananbaum, H.
Abstract: We present new upper limits on an optical counterpart to the central X-ray point source in Cas A using broadband optical/NIR HST images. A series of five STIS images using the 50CCD clear filter totaling an exposure time of 12,402 sec was obtained in January 2001. Except for a likely foreground late-type star at R ~ 26.7 discussed by Kaplan et al. (2001), these images reveal no additional optical point sources brighter than 28.8 mag in equivalent R band and 28.9 mag in equivalent WFPC-2 F675W band within a radius of two arcseconds of the reported Chandra X-ray point source position. In addition, no extended emission or point source is detected near the remnant's newly revised center of expansion located 7 arcseconds to the north (Thorstensen et al. 2001).
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