BOUGARD, B., SLEEWAEGEN, J-M, SPOGLI, L., VEETTIL, SREEJA VADAKKE and GALERA MONICO, J. F., 2011. CIGALA: Challenging the Solar Maximum in Brazil with PolaRxS PROCEEDINGS OF THE 24TH INTERNATIONAL TECHNICAL MEETING OF THE SATELLITE DIVISION OF THE INSTITUTE OF NAVIGATION (ION GNSS 2011). 2572-2579