Target pixel files (TPFs) of each central star in the sample. The red circles are the sources of the Gaia DR2 catalogue in the field with scaled magnitudes (see legend). White crosses indicate the location of the targets. The aperture mask used by the pipeline to extract the photometry is also marked. Pixel scale is 21 arcsec pixel⁻¹. These plots have been created with the tpfplotter code, publicly available at https://github.com/jlillo/tpfplotter.