Low-atmospheric brightenings during the GOES M2.7 flare. Panels a–f: series of AIA 1600 Å images of the active region NOAA 12297 showing the pre- and main flaring phases of the M-class event. The yellow arrows indicate a highly localised bright kernel. The red five-pointed star in panel a indicates the LCO. The green arrow in panel b indicates a secondary bright kernel that appeared only a few minutes prior to the onset of the flare. The green arrow in panel f displays the location of the secondary bright kernel in comparison with the parallel ribbons. The blue and red coloured closed curves in panel e enclose the circular and parallel ribbons, respectively. The sky-blue arrows in panel f indicate the parallel ribbon brightening. The red arrows indicate a localised bright kernel co-temporal with the circular ribbon brightening. Panel g: temporal evolution of AIA 1600 Å intensity from the circular (blue curve) and parallel (red curve) ribbon areas. The horizontal dotted lines indicate the pre-flare values. The dashed vertical lines indicate the onset times of mild intensity enhancement a few minutes prior to the flare. The dotted vertical lines indicate the times of the impulsive intensity enhancements from the circular and parallel ribbons.