Cosmic ray anisotropies during the Oct. 28-31, 2003 Halloween event

Abstract

Using data from the Nagoya muon directional telescopes during the storm of 29 Oct. 2003, the anisotropies were traced at successive UT times. Some features were very prominent, positive in some directions, negative in others. In each, different directional telescopes indicated different magnitudes, implying large directional anisotropies. By tracing the anisotropies in space, one could conclude that the Earth was engulfed by the interplanetary blob and passed slightly in its northern part (same as North of Sun). These results are approximate, as the simple analysis was carried out assuming straight line paths for cosmic rays, while some bending in magnetic fields and some scattering may be involved. Nevertheless, useful information can be obtained even from one muon set up as shown here. Using more copious data from other sources would, of course, give more detailed information.