Time series of images showing the emergence of the active region at three different times during the eight hours: the line-of-sight magnetic field from SDO/HMI (top row) scaled between –800 G and 800 G, chromospheric and coronal response from SDO/AIA at 304 Å, 171 Å, 193 Å, 211 Å and 94 Å (from top to bottom). The field-of-view is 90′′ in both directions centred on (–370′′, –305′′) at 17:00 UT. See text for details. Movies of the time evolution of the emergence are provided as online material.