The Record-Shattering Gamma Ray Burst of February 17 1994

Session 15 -- Gamma Ray Bursts
Oral presentation, Monday, 30, 1994, 10:00-11:30

[15.01] The Record-Shattering Gamma Ray Burst of February 17 1994

K. Hurley (UC Berkeley SSL), M. Boer, M. Niel (CESR), C. Kouveliotou, C. Meegan, G.J. Fishman (MSFC), B.L. Dingus, P.Sreekumar (USRA/GSFC), D.L. Bertsch, C.E. Fichtel, R.C. Hartman, S.D. Hunter, D.J. Thompson (NASA/GSFC), G. Kanbach, H.A. Mayer-Hasselwander, C. von Montigny, M. Sommer (MPI), Y.C. Lin, P.L. Nolan, P.F. Michelson (Stanford), D.A. Kniffen (Hampden-Sydney), J.R. Mattox (CSC/GSFC), E.J. Schneid (Grumman)

A gamma-ray burst which occurred on February 17 1994 was observed by Ulysses, BATSE, COMPTEL, and EGRET. Using Ulysses and BATSE, an annulus of arrival positions with a width of about 5' was obtained which is consistent with all other position determinations. Of particular interest is the EGRET observation of this event. During the 160 second period when the burst was clearly observed by Ulysses and BATSE, EGRET detected 10 photons with energies up to 4.4 GeV. In the 15 minutes which followed, 6 photons were detected. The diffuse gamma ray background in this direction results in about one photon above 30 MeV detected by EGRET in 7 minutes. On the subsequent Compton Observatory orbit, 1.5 hours later, EGRET had 20 minutes of livetime, and 10 gamma rays were detected from the region around the annulus, one with energy 26 GeV. This represents both the longest lasting and the highest energy emission ever observed from a gamma-ray burst source.

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