{
  "bibcode": "2010GCN.10915....1B",
  "body": "N. R. Butler, D. A. Perley, S. B. Cenko, J. S. Bloom (UC Berkeley), A.\nJ. Levan (U. Warwick), and N. R. Tanvir (U. Leicester) report on\nbehalf of a larger collaboration:\n\nBeginning 2010/06/15 01:59 UT (6.1 days post burst) and for a period\nof 14.8 ksec (livetime), Chandra targeted the field of the optically\ndark GRB 100615A (D'Elia et al. 2010, GCN 10841; Foley et al. 2010,\nGCN 10851) with ACIS-S under Director's Discretionary Time.  The X-ray\nafterglow is well detected (210 cts, 0.5-8 keV) at a position\nconsistent with that\nof the Swift GRB and afterglow (GCN 10841; Goad et al. 2010, GCN\n10848). We find:\n\nRA, Dec (J2000) = 11:48:49.34, -19:28:52.0 +/- 0.6\"\n\nThe counts spectrum can be modelled by an absorbed powerlaw, with\nphoton index Gamma = 2.0+/-0.5 (Cash/nu = 11.2/17).  The unabsorbed\nflux is 3.2^{+1.4}_{-0.7} x 10^{-13} erg cm^(-2) s^(-1) (0.5-8 keV).\n\nThere is 6-sigma significant evidence (Delta Cash = 32.4 for 1\nadditional degree of freedom) for a large N_H column 1.0^{+0.4}_{-0.3}\nx 10^22 cm^(-2) (z=0) in excess of the Galactic value (3.3 x10^20\ncm^(-2); Kalberla et al. 2005).  This is in agreement with the XRT\nanalyses (Margutti et al. 2010, GCN 10847) and further indicates that\nGRB 100615A\nis likely a highly extinguished event (see also, Cenko et al. 2010, GCN 10861).\n\nAll uncertainties above are 90% confidence.\n\nWe thank Harvey Tananbaum and the CXO team for permitting and rapidly\nconducting this observation.  This message can be cited.",
  "circularId": 10915,
  "createdOn": 1278017893000,
  "email": "natxbutler@gmail.com",
  "subject": "GRB 100615A: Chandra X-ray ToO Observation",
  "submitter": "Nat Butler at UC berkeley  <natxbutler@gmail.com>",
  "eventId": "GRB 100615A"
}