GCN Circular 1249
Derek W. Fox (Caltech) reports on behalf of the Caltech-NRAO-CARA GRB collaboration: "We have made a comprehensive analysis of the data from two 10-ks Chandra ACIS-I observations of the HETE-IPN localization region for GRB020127 (HETE 1902; GCNs 1229, 1232, 1241). The full source catalogs for these observations contain 48 and 50 sources, respectively; approximately four sources in each epoch are anticipated to be spurious detections. We identify three possible counterparts based on their fading behavior between the Chandra observations (which began at Jan 31.95 UT and Feb 11.46 UT, respectively) and the absence of a bright stellar or galactic counterpart in archival images: Source RA Dec Nsig F1 F2 =================================================================== A14=B16 08 15 01.42(1) +36 46 33.9(1) 13.6 84(16) 19(6) A45 08 15 42.78(7) +36 47 00.2(10) 5.7 28(7) <14 A7 08 14 47.82(3) +36 49 35.4(3) 4.1 13(4) <14 =================================================================== Numbers in parentheses indicate the uncertainty in the preceding digits, and positional uncertainties do not account for the overall Chandra aspect uncertainty of roughly one arcsec. Nsig is the nominal (single-trial) significance of the source detection as reported by wavdetect. F1 and F2 are source count rates for the first and second epochs, respectively, in units of photons cm^(-2) ks^(-1) (0.3-7 keV); upper limits are roughly two-sigma. Source A14 is detected in the second epoch as source B16, while neither source A45 nor source A7 are detected in the second epoch. We note explicitly that the sources above are not the only sources within the HETE-IPN localization to show variability between the two epochs; however, they are the only sources, not associated with bright stellar or galactic counterparts, that show convincing evidence of a decline in flux. The full source catalog for the two observations is available at the following URL: http://www.astro.caltech.edu/~derekfox/grb020127/chandra.html Given the strength of source A14 (=B16) in the first observation, and its observed fading behavior -- which is consistent with a t^(-1.2) power-law referred to the epoch of GRB020127 -- we consider source A14 to be the most likely candidate for the afterglow of GRB020127."