Cosmic Ray Latitude Survey: 1996-1997

During the 1996-97 austral summer, a period of solar minimum, we operated a neutron monitor on board the ship Italica of the Italian Antarctic Programme to record cosmic ray neutron intensities in seas from Italy to Antarctica and back. This survey provided a full coverage of cut-off rigidities and the possibility of repeating the measurements at least twice at the same cut-offs. The main purpose of this research was the determination of an accurate latitude curve of cosmic ray nucleonic intensity during solar minimum to be used for obtaining the coupling function appropriate for this phase of solar cycle. Accuracy was achieved through reliable instrumentation and proper control of the experiment and by determining and applying for the first time all corrections, for (1) changes in vertical atmospheric mass column, by taking into account wind effect; (2) oscillations of the ship produced by sea roughness; (3) atmospheric temperature changes; (4) primary cosmic ray temporal variations including north-south asymmetry; and (5) temporal variations in the cosmic ray east-west effect, caused by asymmetric shielding on the ship.