{
  "bibcode": "2002GCN..1229....1R",
  "body": "GRB020127(=H1902): Localization of a Double-Peaked GRB by HETE\n\nG. Ricker, J-L Atteia, N. Kawai, D. Lamb, and S. Woosley on behalf of\nthe HETE Science Team;\n\nG. Crew, R. Vanderspek, J. Doty, G. Monnelly, J. Villasenor, N. Butler,\nT. Cline, J.G. Jernigan, A. Levine, F. Martel, E. Morgan, G.\nPrigozhin, J. Braga, R. Manchanda, and G. Pizzichini, on behalf of\nthe HETE Operations and HETE Optical-SXC Teams;\n\nM. Matsuoka, Y. Shirasaki, T. Tamagawa, K. Torii, T. Sakamoto,\nA. Yoshida, E. Fenimore, M. Galassi, T. Tavenner, T. Donaghy, and\nC. Graziani, on behalf of the HETE WXM Team;\n\nM. Boer, J-F Olive, J-P Dezalay, and K. Hurley on behalf\nof the HETE FREGATE Team;\n\nwrite:\n\nAt 20:57:24.73 UTC (75444.73 s UT) on 27 January, the HETE FREGATE \nand WXM instruments detected and localized a double-peaked GRB. The \nburst, H1902, was promptly reported as a GCN Alert Notice within 97 \nseconds of the detection time. [Because of the proximity of the \nnearly-full moon to the HETE optical cameras, the burst alert \ndownlink contained no real time optical aspect solution, even though \nthere was an accurate on-board X-ray localization. When this \ncondition arises, the ground relay software computes a nominal \nlocalization assuming the satellite is pointed anti-sun, and \nincreases the error circle diameter to a nominal 4 degrees. For this \nburst, the actual pointing direction was unusually far from nominal \n(i.e. ~8 degrees offset).]\n\nAccurate aspect was derived for H1902 from a full data set on the \nground. In a followup GCN Notice issued 1.76 hours after the GRB, the \nresult of an initial ground analysis localization was reported with a \n90% confidence error circle radius of 12 arcmin. Further ground \nanalysis of the optical aspect data has produced a significantly \nimproved location which can be expressed as a circle with a 90% \nconfidence radius of 8 arc minutes centered at:\n\nRA = +08h 15m 05.7s, Dec = +36d 44' 31\" (J2000)\n\nThe revised error circle reported here is displaced by 9 arc minutes \nfrom the  best-fit location found in the initial HETE ground analysis \nand reported in a GCN Notice (at 27 Jan 2002 22:43:00 UT).\n\nGRB020127(=H1902) consists of two peaks separated by 5.5s, with \ndurations in the FREGATE 32-400 keV band of ~2s and 0.7s, \nrespectively. A total of 870 counts were detected by FREGATE in the \nfirst peak, and 580 counts in the second peak, respectively.  In the \n8-40 keV FREGATE band, the peak flux in 0.073s was >2 x 10-7 ergs \ncm-2 s-1(ie >7 x Crab flux). In the 2-25 keV WXM band, the \nstatistical significance of the burst was 21 sigma.\n\nThis message is quotable.",
  "circularId": 1229,
  "createdOn": 1012189984000,
  "email": "grr@space.mit.edu",
  "subject": "GRB020127(=H1902): Localization of a Double-Peaked GRB by HETE",
  "submitter": "George Ricker at MIT  <grr@space.mit.edu>",
  "eventId": "GRB 020127"
}