Astron. Astrophys. Suppl. Ser. 138, 595-596

Search for high energy GRBs with EASTOP

M. Aglietta^1,2 - B. Alessandro² - P. Antonioli⁵ - F. Arneodo⁴ - L. Bergamasco^2,3 - M. Bertaina^2,3 - C. Castagnoli² - A. Castellina^1,2 - A. Chiavassa^2,3 - G. Cini^2,3 - B. D'Ettorre Piazzoli⁶ - G. Di Sciascio⁶ - W. Fulgione^1,2 - P. Galeotti^2,3 - P.L. Ghia^1,2 - M. Iacovacci⁶ - G. Mannocchi^1,2 - C. Morello^1,2 - G. Navarra^2,3 - O. Saavedra^2,3 - G.C. Trinchero^1,2 - P. Vallania^1,2 - S. Vernetto^1,2 - C. Vigorito^2,3

Send offprint request: S. Vernetto

1 - Istituto di Cosmo-Geofisica del CNR, Torino, Italy
2 - Istituto Nazionale di Fisica Nucleare, Torino, Italy
3 - Dipartimento di Fisica Generale dell' Università, Torino, Italy
4 - Dipartimento di Fisica dell' Università and INFN-LNGS, L' Aquila, Italy
5 - Istituto Nazionale di Fisica Nucleare, Bologna, Italy
6 - Dipartimento di Scienze Fisiche dell' Università and INFN, Napoli, Italy
e-mail: vernetto@lngs.infn.it

Received December 18, 1998; accepted March 10, 1999

Abstract:

A search for GRBs of energy E>10 GeV has been performed by studying the single particle counting rate of the EAS array EASTOP. No candidates have been observed in coincidence with 292 BATSE GRBs and the typical upper limits obtained on the energy fluence are $F(10~{\rm GeV}\div 1~{\rm TeV})\sim 10 ^{-4}\div 10^{-3}~{\rm erg}~{\rm cm}^{-2}$ for the events with zenith angle $\theta<30^{\circ}$. A single candidate has been observed in the "all sky" survey mode during 1.5 10³ days.

Key words: gamma-ray bursts