Published data from: 'Developing a nowcasting capability for X-Class solar flares using VLF radiowave propagation changes.' Authors: Harriet George, Craig J. Rodger, Mark A. Clilverd, Kathy Cresswell-Moorcock, James B. Brundell, Neil R. Thomson. DESCRIPTION OF DATA This dataset contains the phase and amplitude data from VLF radio transmitter NPM (Hawaii, 21.4 kHz, 21.4⁰N, 158.2⁰E) recorded at the field-site for New Zealand's Scott Base, Arrival Heights, in Antarctica (77.8⁰S, 166.8⁰E). The propagation path is ~11 Mm long, oriented nearly north-south, with the mid-point at 28.9⁰S, 164.4⁰W. Prof. Craig J Rodger & Dr. James B Brundell Space Physics Group, Department of Physics University of Otago, New Zealand http://www.physics.otago.ac.nz/nx/space/space-physics-home.html