TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2566 SUBJECT: HETE/IPN localization of GRB040403A (=H3143, a long burst) and GRB040403B(=H3144, a short/hard burst) DATE: 04/04/09 21:16:39 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley, on behalf of the HETE GRB Team, E. Mazets and S. Golenetskii, on behalf of the Konus-Wind GRB team, G. Ricker, J-L Atteia, N. Kawai, D. Lamb, S. Woosley, J. Doty, R. Vanderspek, J. Villasenor, G. Crew, A. Dullighan, N. Butler, J.G. Jernigan, A. Levine, F. Martel, E. Morgan, G. Prigozhin, J. Braga, R. Manchanda, G. Pizzichini, Y. Shirasaki, C. Graziani, M. Matsuoka, T. Tamagawa, K. Torii, T. Sakamoto, A. Yoshida, E. Fenimore, M. Galassi, T. Tavenner, T. Donaghy, M. Boer, J-F Olive, and J-P Dezalay, on behalf of the HETE GRB team, and T. Cline, on behalf of the HETE and Konus-Wind GRB teams, report: HETE detected two GRBs on 2004 April 03; the presence of Sco X-1 in the WXM field-of-view made analyses and reporting of their results somewhat complicated. Both events were also detected by Konus-Wind, but by no other instruments in the IPN. GRB040403A was detected as trigger #H3143 at 16:55:03 UT (60903 SOD). It was detected primarily in the Fregate 30-400 keV band. The absence of a signal in the 7-40 and 7-80 keV bands indicates that the burst was detected at the edge of the Fregate FOV; there was no discernable signal in the WXM. The WXM flight software looked for a real-time localization for GRB040403A, but was able only to localize Sco X-1: this position was distributed to the GCN 27 seconds after burst detection. After detailed analysis of the WXM data, the localization was retracted two hours after the initial report. Due to a software error, the retraction Notice indicated that the trigger was not a real GRB; H3143 is indeed a real GRB, but the position distributed in real time was not that of the burst. A combination of triangulation, the Konus ecliptic latitude response, and HETE Earth-blocking give a large 5-sided error box whose shape is complex, and whose corners are at: RA(2000) Decl(2000) 263 +20.5 282 +33.1 302 +37.4 308 +37.8 304 +25.7 A map has been posted at ssl.berkeley.edu/ipn3/040403A. As observed by Konus-Wind, this burst had a duration of 98s, a 20-2000 keV fluence of 6E-5 erg/cm2 (or 4E-5 in 30-400 keV range), a 20-2000 keV peak flux ~ 2.6E-6 erg/cm2 s, and an Epeak=340+/-20 keV. GRB040403B was detected as trigger #H3144 at 23:23:55 UT (84236 SOD). As observed by FREGATE, it consists of two short (0.5s) spikes separated by ~0.8s. The burst is seen most strongly in the 30-400 keV band with an Epeak well above this range. GRB040403B therefore qualifies as a short/hard burst. The burst was marginally detected by the WXM; unfortunately, the presence of Sco X-1 in the WXM FOV makes localization of this burst impossible. The SXC was not operating at this time because of the full moon. Triangulation gives an annulus of location centered at RA, Decl=127.559, +21.669, whose radius is 70.529 +/- 2.155 degrees (3 sigma). The WXM field of view limits this annulus to an error box with the following corners: RA(2000) Decl(2000) 188.213 -1.116 191.330 -15.436 199.758 +36.566 212.802 +40.309 A map may be viewed at ssl.berkeley.edu/ipn3/040403B. As observed by Konus-Wind, this burst had a 20-2000 keV fluence ~ 2E-6 erg/cm2, a peak flux ~ 4.5E-6 erg/cm2 s, and an Epeak=1300+/-1000 keV. This message can be cited.