Signatures of a magnetic transient in the photosphere and the corona. The black curve shows the photospheric magnetic flux integrated over the area that is covered by the minor negative-polarity features as a function of time from region 3 in Fig. 1a from SST observations (see also Fig. 2). To avoid noise, only pixels with a magnetic flux density above 10 G are considered for the integration. The blue curve shows the coronal EUV emission recorded by the AIA 193 Å channel from the blue box in Fig. A.1d overlying SST region 3. See Sect. 2 for details.