CRISP filtergrams at the core of the Hα line (top left). All other images are in Ca iiλ8542. A wide-band image showing the photosphere is displayed in the top right panel. The lowermost four panels show the chromosphere at Δλ = −150 mÅ from line core in Stokes I (middle left), Q/I (middle right), U/I (bottom left) and V/I (bottom right). The arrows on the wide-band image indicate the direction to the solar North and to disk center, respectively. The largest white box indicated in the wide-band image highlights the subfield that has been used for the non-LTE inversions, whereas the smaller square indicates a subfield used to study running penumbral waves.