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Astron. Astrophys. Suppl. Ser.
Volume 138, Number 3, September 1999
Gamma-Ray Bursts in the Afterglow Era Contents Rome, November 3-6, 1998
Page(s) 539 - 540
Published online 15 September 1999
DOI: 10.1051/aas:1999343

Astron. Astrophys. Suppl. Ser. 138, 539-540

Gamma-ray burst beaming constraints from afterglow light curves

J.E. Rhoads

Kitt Peak National Observatory, NOAO, P.O. Box 26732, Tucson, AZ 85726-6732, U.S.A.

Received December 24, 1998; accepted April 29, 1999


The beaming angle $\zeta_{\rm m}$ is the main uncertainty in gamma ray burst energy requirements today. We summarize predictions for the light curves of beamed bursts, and model the R band light curve of GRB 970508 to derive $\zeta_{\rm m}\mathrel{\mathchoice {\vcenter{\offinterlineskip\halign{\hfil
 ...align{\hfil$\scriptscriptstyle ... . This yields an irreducible minimum energy requirement of $3.4 \ 10^{49}$ ergs to power the afterglow alone.

Key words: gamma-ray: bursts

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