AAS 207th Meeting, 8-12 January 2006
Session 14 Highlights and Discoveries from INTEGRAL
Poster, Monday, 9:20am-7:00pm, January 9, 2006, Exhibit Hall

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[14.06] INTEGRAL Observations of the Nearby, Under Luminous Gamma-Ray Burst GRB031203

C. Shrader (NASA GSFC)

The gamma-ray burst GRB031203 was discovered by the INTEGRAL burst alert system in near real time on December 3, 2003. Previously published studies of its after glow emission indicated that it had one of the lowest recorded GRB redshifts, z=0.105 corresponding to a nominal distance of 40 Mpc. Furthermore, the prompt burst emission indicated a sub-200-keV fluence of <1050 ergs, making its isotropic-equivalent luminosity one of the lowest among documented cases. However, the measurements on which these studies were based are hampered by the limited sensitivity above 200 keV of the INTEGRAL/ISGRI instrument, and by the fact that the approximate 10-degree off-axis angle put the event outside of its fully coded field of view (FCFOV). The contribution to the burst fluence above 200 keV, and the broad-band spectral energy distribution are critical issues in an accurate characterization of this apparently anomalous GRB. We were thus motivated to re-analyze the INTEGRAL data for GRB031203, with an emphasis on SPI, which has a substantially larger FCFOV, and greater sensitivity above 200 keV than IBIS. We present the results and interpretation of our analysis.

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