Context image of the pore studied in this article. Left panel: a wider FOV of the active region as observed by the SDO/HMI instrument at 10:00:05 UT on 1 September 2019. The overlaid black box outlines the region plotted in the other panels. Right panels: total FOV of the GRIS instrument is plotted in three different diagnostics: The top row plots a magnetogram returned by the SDO/HMI instrument; the middle row plots the Stokes-V component sampled by GRIS at 15 647.6 Å; and the bottom row plots the Stokes-I intensity in the continuum at a wavelength position of 15 646.8 Å. The scan that sampled the GRIS images was started at 10:00:01 UT. Artefacts of the stitching process can be seen in the continuum image. The red cross indicates the pixel discussed in Fig. 2.