{
  "bibcode": "2009GCN.10232....1F",
  "body": "D. B. Fox (Penn State) and E. Berger (Harvard) report:\n\n\"We observed the Swift/BAT localization region for GRB 091117\n(Cummings et al., GCN 10171; Sakamoto et al., GCN 10180) with the\nChandra X-ray Observatory + ACIS, positioned at the ACIS-S3 aimpoint,\nin a 20.1 ksec integration with mean epoch Nov 21.85 UT, 4.1 days\nafter the burst trigger.\n\nAnalysis of these data reveals the presence of nine X-ray sources\nwithin and near the BAT localization region, including the two X-ray\nsources identified in previous Swift XRT observations (Berger, GCN\n10173; D'Elia et al., GCN 10177).  Comparison to deep optical imaging\nof the region from Magellan (Berger & Mulchaey, GCN 10174; Berger &\nMomcheva, GCN 10183) reveals point-like (nuclear, stellar, or\nunresolved galactic) optical counterparts to all but three of these\nsources:\n\n    #      CXOU J         Sigma    Cts  Unc   Comments\n   ==========================================================\n    1  020353.36-165830.0  54.0  119    11    XRT-1; Nuclear\n    2  020356.65-165659.1  44.5  101    10    XRT-2; Nuclear\n    3  020353.68-165428.1  14.7   34.9  6.5   Stellar\n    4  020338.35-165547.3   8.7   23.0  5.0   Stellar\n    5  020347.45-165927.6   6.2   13.4  3.7   (not imaged)\n    6  020342.46-165706.7   4.8    9.7  3.2   Stellar\n    7  020345.74-165817.1   4.2    8.7  3.0   Near galaxy\n    8  020345.21-165818.2   3.8    7.7  2.8   Stellar\n    9  020349.61-165430.5   3.7    7.6  2.8   No counterpart\n   ==========================================================\n\nThe table above provides source names/coordinates (J2000) as\ndetermined from the Chandra astrometric solution, the significance of\ndetection in \"wavdetect\" analysis over the 0.3-8.0 keV bandpass, and\nestimated counts and uncertainties (0.3-8.0 keV) for each source. The\nnature of the optical counterpart, if any, is also provided.\n\nWe note that the two brightest X-ray sources, also observed by Swift,\nare coincident to within <1 arcsec with the active nuclei of the two\nbrightest galaxies in the region: Chandra source #1 (XRT-1) with the\nactive nucleus of the face-on spiral galaxy at z=0.096 (Chornock &\nBerger, GCN 10176), and Chandra source #2 (XRT-2) with the active\nnucleus of 2MASX J02035665-1656585 at z=0.092.  Source #1 appears\n(2.8-sigma confidence) to have faded since the first epoch of Swift\nobservations, consistent with inferences from Swift XRT data (Fox, GCN\n10179); however, the coincidence of sources #1 and #2 with AGN\nsuggests that neither of these objects is associated with GRB 091117.\n\nChandra source #7 is notable for being located 2.4 arcsec from the\ncenter of an edge-on galaxy that is resolved in our Magellan imaging.\"",
  "circularId": 10232,
  "createdOn": 1259782600000,
  "email": "dfox@astro.psu.edu",
  "subject": "GRB 091117:  Chandra Observations",
  "submitter": "Derek Fox at PSU  <dfox@astro.psu.edu>",
  "eventId": "GRB 091117"
}