This is a must-have module for the person that follows the Solar-Terrestrial Data closely. This module's data is updated regularly from real-world data which drives the HamSphere propagation models. This module includes the K and A indices which indicate the level of geomagnetic activity impacting the Earth’s ionosphere hence propagation. Generally speaking, the higher the A-Index goes, the better HF propagation will be. For a complete understanding of how this all correlates to propagation, see http://www.hamqsl.com/solar.html.