High-resolution Two-Dimensional Map of the Solar-Time Anisotropy Obtained by the GRAPES-3 Large-Area Muon Telescope

In the analysis of the anisotropy of the galactic cosmic rays caused by the solar modulation below 1 TeV, time series graphs with time on the horizontal axis and cosmic ray intensity as the vertical axis had been widely adopted and other style of the graphs called harmonic vector diagrams had also been used. These methods are the time series analyses, and because of the horizontal axis (time), the graph is often misinterpreted as a "temporal variation," even though it must be regarded as an intrinsically "spatial distribution." This paper presents a high-resolution two-dimensional map of the solar time anisotropy using the GRAPES-3 large-area muon telescope at Ooty, south India, which has an excellent capability of observing the muon intensity in 169 directions within a 50 degrees zenith angle.