{
  "bibcode": "2002GCN..1249....1F",
  "body": "Derek W. Fox (Caltech) reports on behalf of the Caltech-NRAO-CARA GRB\ncollaboration:\n\n\"We have made a comprehensive analysis of the data from two 10-ks\nChandra ACIS-I observations of the HETE-IPN localization region for\nGRB020127 (HETE 1902; GCNs 1229, 1232, 1241).  The full source\ncatalogs for these observations contain 48 and 50 sources,\nrespectively; approximately four sources in each epoch are anticipated\nto be spurious detections.  We identify three possible counterparts\nbased on their fading behavior between the Chandra observations (which\nbegan at Jan 31.95 UT and Feb 11.46 UT, respectively) and the absence\nof a bright stellar or galactic counterpart in archival images:\n\n Source        RA               Dec           Nsig     F1     F2\n===================================================================\n  A14=B16   08 15 01.42(1)   +36 46 33.9(1)   13.6   84(16)  19(6)\n  A45       08 15 42.78(7)   +36 47 00.2(10)   5.7   28(7)  <14\n   A7       08 14 47.82(3)   +36 49 35.4(3)    4.1   13(4)  <14\n===================================================================\n\nNumbers in parentheses indicate the uncertainty in the preceding\ndigits, and positional uncertainties do not account for the overall\nChandra aspect uncertainty of roughly one arcsec.  Nsig is the nominal\n(single-trial) significance of the source detection as reported by\nwavdetect.  F1 and F2 are source count rates for the first and second\nepochs, respectively, in units of photons cm^(-2) ks^(-1) (0.3-7 keV);\nupper limits are roughly two-sigma.  Source A14 is detected in the\nsecond epoch as source B16, while neither source A45 nor source A7 are\ndetected in the second epoch.\n\nWe note explicitly that the sources above are not the only sources\nwithin the HETE-IPN localization to show variability between the two\nepochs; however, they are the only sources, not associated with bright\nstellar or galactic counterparts, that show convincing evidence of a\ndecline in flux.  The full source catalog for the two observations is\navailable at the following URL:\n\n  http://www.astro.caltech.edu/~derekfox/grb020127/chandra.html\n\nGiven the strength of source A14 (=B16) in the first observation, and\nits observed fading behavior -- which is consistent with a t^(-1.2)\npower-law referred to the epoch of GRB020127 -- we consider source A14\nto be the most likely candidate for the afterglow of GRB020127.\"",
  "circularId": 1249,
  "createdOn": 1013746169000,
  "email": "derekfox@astro.caltech.edu",
  "subject": "GRB020127:  Comparison of Chandra Epochs and Identification of Possible Counterparts",
  "submitter": "Derek Fox at CIT  <derekfox@astro.caltech.edu>",
  "eventId": "GRB 020127"
}