Target pixel files (TPFs) of three central stars in the sample (marked with white crosses) obtained with TPFPLOTTER. The red circles are sources from the Gaia DR3 catalogue in the field with scaled magnitudes (see legend). The aperture mask used by the pipeline to extract the photometry is also marked. The pixel scale is 21 arcsec pixel⁻¹ . Left, middle and right panels represent examples of fields with negligible, minimal or severe contamination, respectively (see Sect. 2.2 for more details).