The Heart of World’s Largest Solar Telescope Begins to Beat

The world's largest solar telescope, the U.S. National Science Foundation (NSF) Daniel K. Inouye Solar Telescope in Hawaii, has reached an important milestone. After almost 15 years of preparation, the German instrument for the Inouye Solar Telescope, the Visible Tunable Filtergraph (VTF), has now taken its first images. The imaging spectro-polarimeter was developed and built at the Institute for Solar Physics (KIS) in Freiburg (Germany). The Max Planck Institute for Solar System Research (MPS) in Göttingen (Germany) is a partner in the project. The data published now were obtained during the technical commissioning of the instrument. VTF analyzes the sunlight captured by the Inouye Solar Telescope in more detail than ever before and, among other things, extracts information on the flow velocity of the solar plasma and the magnetic field strength at the visible surface of the Sun and in the directly adjacent gas layers above. Even in the current technical test phase, VTF is making smallest structures visible. In later scientific operation, when the data is extensively post-processed, the resolution will improve further.