{
  "bibcode": "2005GCN..3415....1B",
  "body": "D. N. Burrows, D. Grupe (PSU), C. Kouvelioutou, S. Patel (MSFC), N. Gehrels\n(GSFC), P. Meszaros (PSU), B. Zhang (UNLV), and R. Wijers (U. Amsterdam)\nreport:\n\nWe have observed the field of the short burst GRB 050509b (Hurkett et al. 2005,\nGCN 3381) with the Chandra ACIS instrument.  The 50 ks observation was centered\nat the Swift XRT afterglow position reported by Kennea et al. (2005; GCN 3383).\nWithin the ACIS S3 detector 20 point sources are found by XIMAGE in our\npreliminary analysis.  Two of these sources fall within the revised 8 arcsecond \nradius error circle reported by Rol et al. (2005; GCN 3395).  The coordinates \nand count rates of these sources are:\n\n#5:  12 36 14.0 +28 59 02.5  2.46E-04+/-8.6E-05\n\n#8:  12 36 13.9 +28 59 07.9  1.94E-04+/-7.8E-05 \n\nSource #5 is 2.0 arcseconds from the revised XRT position and is tentatively\nidentified as the X-ray afterglow.  However, the source intensity is too low for\nus to to verify whether this source is fading during our observation.  \n\nAssuming a Crab-like spectrum absorbed by galactic NH (1.5E20), \nthis count rate corresponds to a flux of 1.6E-15 cgs (0.2-10 keV). \nCombined with the Swift XRT flux measurement at early times, we estimate a\npower-law decay index of approximately -1.0 over the 200 ks interval between \nthe two observations.  Confirmation of this afterglow candidate will require\nadditional Chandra observations to see whether any of these sources are fading.",
  "circularId": 3415,
  "createdOn": 1115882462000,
  "email": "dxb15@psu.edu",
  "subject": "Chandra observation of GRB 050509b",
  "submitter": "David Burrows at PSU/Swift  <dxb15@psu.edu>",
  "eventId": "GRB 050509B"
}