{
  "bibcode": "2004GCN..2716....1B",
  "body": "GRB040912(=H3557): Observations with the Chandra X-ray Observatory\n\nN. Butler, P. Ford, G. Ricker, R. Vanderspek, J. Villasenor,\nP. Csatorday (MIT); D.  Lamb (U. Chicago); and J.G. Jernigan (UCB), on \nbehalf of a Chandra GRB ToO Team,\n\nwrite:\n\nOn 15 September 2004, the Chandra Observatory targeted the field of \nGRB040912, an X-ray flash localized by the HETE satellite (=H3557; \nButler et al, GCN 2701). The 20 ksec observation spanned the \ninterval 21:57 UT on 15 September to 3:48 UT on 16 September, 3.32 - 3.57\ndays after the burst. The WXM error circle from Butler et al. was completely \ncontained within the field-of-view of the Chandra ACIS-I array.\n\nWithin the WXM error region, we detect 22 sources with more than 6\nsource counts in the 0.5-8 keV band:\n\n #      Chandra Name           RA           DEC         Cts   HR\n 1 CXOU J235631.0-005946    23 56 30.96  -0  59 46.1    55   -0.5\n 2 CXOU J235700.0-010009    23 56 59.96  -1   0  9.7    40   -0.3\n 3 CXOU J235712.2-005942    23 57 12.17  -0  59 42.1    33   -0.3\n 4 CXOU J235642.9-005520    23 56 42.91  -0  55 20.4    32   -0.7\n 5 CXOU J235645.7-005655    23 56 46.71  -0  56 54.9    32   -0.3\n 6 CXOU J235707.6-005713    23 57  7.57  -0  57 12.6    31    0.8\n 7 CXOU J235716.4-010109    23 57 16.37  -1   1  8.7    27   -0.2\n 8 CXOU J235639.1-005556    23 56 39.10  -0  55 55.8    20    0.9\n 9 CXOU J235651.2-005513    23 56 51.17  -0  55 12.5    17   -0.3\n10 CXOU J235636.7-005431    23 56 36.74  -0  54 31.2    15   -0.6\n11 CXOU J235711.1-005637    23 57 11.12  -0  56 37.1    12   -0.2\n12 CXOU J235637.3-010160    23 56 37.26  -1   1 59.9    12   -0.6\n13 CXOU J235656.4-005839    23 56 56.42  -0  58 39.2    11   -0.1\n14 CXOU J235700.1-005713    23 57  0.09  -0  57 12.6    11   -1.0\n15 CXOU J235659.8-005903    23 56 59.83  -0  59  2.8    10   -0.6\n16 CXOU J235649.1-010344    23 56 49.07  -1   3 44.2     9    0.4\n17 CXOU J235700.4-010018    23 57  0.36  -1   0 17.6     9   -0.7\n18 CXOU J235646.4_005621    23 56 46.45  -0  56 21.4     8    1.1\n19 CXOU J235647.0-010045    23 56 46.97  -1   0 45.1     8    0.0\n20 CXOU J235648.8-010319    23 56 48.81  -1   3 18.6     8   -1.0\n21 CXOU J235704.0-005859    23 57  4.03  -0  58 58.8     8   -0.2\n22 CXOU J235707.2-010420    23 57  7.18  -1   4 19.6     7    0.4\n\nWe estimate a position uncertainty of 1.0\" for the Chandra sources. \nAstrometry was performed using five stars from the USNO-A2 catalog.\nThe column labeled HR in the table above refers to the hardness\nratio ( Cts_2-8keV - Cts_0.5-2keV )/ Cts_0.5-8 keV.  This quantity is\ntypically in the range -0.5 to -0.1 for GRBs at high Galactic latitude\nand attenuated by the Galactic absorption only.\n\nAn image of the Chandra data, with the detected sources overlaid, can\nbe found at http://space.mit.edu/HETE/Bursts/GRB040912.\n\nWe gratefully acknowledge the timely assistance of the observatory staff \nat the Chandra Science Center in arranging for the acquisition and \npreliminary processing of these data.\n\nThis message may be cited.",
  "circularId": 2716,
  "createdOn": 1095358906000,
  "email": "roland@space.mit.edu",
  "subject": "GRB040912(=H3557): Observations with the Chandra X-ray Observatory",
  "submitter": "Roland Vanderspek at MIT  <roland@space.mit.edu>",
  "eventId": "GRB 040912"
}