//////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1103 SUBJECT: GRB010928(=H1770): Localization of a Long GRB by HETE DATE: 01/09/28 23:03:50 GMT FROM: George Ricker at MIT GRB010928(=H1770): Localization of a Long GRB by HETE G. Ricker, D. Lamb, and S. Woosley on behalf of the HETE Science Team; G. Crew, R. Vanderspek, J. Doty, G. Monnelly, J. Villasenor, N. Butler, T. Cline, J.G. Jernigan, A. Levine, F. Martel, E. Morgan, G. Prigozhin, J. Braga, R. Manchanda, and G. Pizzichini, on behalf of the HETE Operations and HETE Optical-SXC Teams; N. Kawai, M. Matsuoka, Y. Shirasaki, T. Tamagawa, K. Torii, T. Sakamoto, A. Yoshida, E. Fenimore, M. Galassi, T. Tavenner, T. Donaghy, and C. Graziani, on behalf of the HETE WXM Team; J-L Atteia, M. Boer, J-F Olive, J-P Dezalay, and K. Hurley on behalf of the HETE FREGATE Team; write: At 16:53:46.56 UTC (60826.56 s UT) on 28 September, the HETE FREGATE and WXM instruments detected and localized a long GRB. The burst, H1770, was promptly reported as a GCN Alert Notice within 13 seconds of the detection time. The burst is seen in the WXM X detector and is therefore well-localized in the X direction; the burst was apparently near the edge of the coded FOV of the WXM Y detector, resulting in a large uncertainty in the Y direction localization. The X-detector data gives a good (+/- 6 arcmin) localization in the X direction and crude limits on Y, resulting in a localization that is a long, thin strip. The coordinates (J2000) of two points along one side of the strip are: R.A. = 23h29m44s.1, Dec. = 29o39'36"; R.A. = 23h27m05s.7, Dec. = 31o34'34" The coordinates (J2000) of two points along the other side of the strip are: R.A. = 23h30m42s.9, Dec. = 29o43'41"; R.A. = 23h28m04s.5, Dec. = 31o38'42" The length of the strip is uncertain. Our best estimate is that it is less than 10 degrees in length, and is centered on R.A. = 23h28m55s.1, Dec. = 30o39'11". The burst duration was ~40 s, with two peaks separated by ~20 s. In the 8-85 keV band, a total of 6,330 counts were detected during the burst, corresponding to a fluence of ~1 x 10-6 ergs cm-2; the peak flux was >7 x 10-8 ergs cm-2 s-1 (ie >2 x Crab flux). In the 32-400 keV band, a total of 9,530 counts were detected during that interval, corresponding to a fluence of ~3 x 10-6 ergs cm-2; the peak flux was >2 x 10-7 ergs cm-2 s-1 (ie >14 x Crab flux). Further refinement of the X localization is in progress; a further attempt is also being made to improve the coarse Y localization. Follow-up observations of this transient are encouraged.