Next Contents Previous

2.7. Angular Distribution

One of the most remarkable findings of BATSE was the observation that the angular distribution of GRBs' positions on the sky is perfectly isotropic. Early studies had shown an isotropic GRB distribution [115] which have even led to the suggestion that GRBs are cosmological [116]. In spite of this it was generally believed, prior to the launch of BATSE, that GRBs are associated with galactic disk neutron star. It has been expected that more sensitive detectors would discover an anisotropic distribution that would reflect the planar structure of the disk of the galaxy. BATSE's distribution is, within the statistical errors, in complete agreement with perfect isotropy. For the first 1005 BATSE bursts the observed dipole and quadrupole (corrected to BATSE sky exposure) relative to the galaxy are: <cos theta> = 0.017 ± 0.018 and <sin2b - 1/3> = - 0.003 ± 0.009. These values are, respectively, 0.9sigma and 0.3sigma from complete isotropy [39].