Website latest update on July 27, 2021

Welcome to the GeoMagSphere Website. In these pages you can find information about the Earth magnetic field and its interaction with the primary cosmic rays - both of galactic and solar origin - and the calculation of the rigidiy cutoff for cosmic rays, for protons, electrons, ions and antiparticles, up to the top of the atmosphere, as a function of solar activity.

The calculators will be made gradually available in order to estimate, for istance, the rigidity cutoff and the effect of cosmic rays in different periods and for different locations, on different charged cosmic ray particles. In the meanwhile a simple calculation of the vertical rigidity cutoff is available with both External Field Models T96 and TS05.

The calculators, based on the program that was developed by the INFN Milano-Bicocca (Italy) and IEP-SAS space physic (Slovakia) groups, reconstructs the particle trajectories inside the magnetosphere. In the present website version, we use IGRF-12 as Internal Magnetic Field Model of Earth, updated at 2015, using a linear approximation for the period 2015-2020. As External Magnetic Field Model, we combine both Tsyganenko 1996 and Tsyganenko and Sitnov 2005 models.

In the current version, the back-tracing code is 2016.1.0. With respect to version 2013.1.0, a new magnetopause, due to Shue et al. (1997), is used. Its size and shape depends on the solar activity, mainly through the solar wind ram pressure (Tsyganenko and Sitnov 2005). In the current version, an automatic switch between the two external field models in relation to the solar wind pressure is added.

This project is part of the activities on going at the AMS-02 Milano Bicocca (Italy) group and IEP-SAS space physic (Kosice, Slovakia).

Currently, sr-niel  (see also ASIF implementation agreements 2017-22-HD.0 ASI-ENEA and 2017-15-HD.0 ASI-INFN), helmod and geomagsphere websites are supported within the space radiation activities of ASIF framework.


2011 11h Bx Diff2012 3h Bx Diff



Amount of data as a function of the difference, regarding the component \(B_x\) of the magnetic field, between the model predictions (IGRF alone in red, IGRF+T89 in green and IGRF+TS05 in blue) and the Cluster satellite measurements during 2 - 7 November 2011 (left) and 5 - 9 March 2012 (right).


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Example of solar proton analysis obtained from AMS-02 data using the geomagnetic cutoff due to both IGRF and TS05 magnetic field models [presented at ECRS-2016]


GSM XYZ 0p5 1GV 816 828


Secondary protons detected by AMS-02 during the Solar Event of Aug. 9th 2011. GSM projections YZ, XY and XZ of final positions (in unit of Earth radii) for particles detected during "polar" pass of 8:16-8:28 AM. Proton rigidity ~1GV. The shape of the Aurora are clearly seen. Preliminaty analysis done in collaboration with the University Of Hawaii at Manoa UH log

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