AIA 94 Å images at 22:10 UT with an s-shaped sigmoid and flux rope prior to flare onset (panel a) and the two flaring loops and circular ribbon formed during the flare (22:18:37 UT) (panel b). Red and black contours denote 500 and −500 Gauss LOS magnetic field respectively. HXR emission at 50−100 keV (solid contours) highlights two closely spaced sources in panel b, with TD source (black cross) located close to the northern HXR source. The context images of both HMI continuum and LOS magnetogram at 22:18:37 UT are given in panels c and d, with detected source location contours from the statistical test on full-angle egression power maps. Regions of a significant acoustic signal are given for the 4–7 mHz pass bands, in addition to the location of the time– distance source origin. HXR emission is represented as dashed contours in panels c and d for clarity.