[Brazilian Geophysical Society 15th International Congress of the Brazilian Geophysical Society & EXPOGEF, Rio de Janeiro, Brazil, 31 July-3 August 2017 - Rio de Janeiro (31 July to 3 August)] 15th International Congress of the Brazilian Geophysical Society & EXPOGEF, Rio de Janeiro, Brazil, 31 July-3 August 2017 - Conducting an absolute gravity base tie in other to measure the reference gravity value at the Marine Gravity System-6 installed on the Hydro-Oceanographic Research Ship Vital de Oliveira (H39)