Configuration of the coronal magnetic field during the passage of comet Lovejoy, as seen from an Earth vantage point. The surface displays the photospheric radial magnetic field of a SolarSoft synchronic map, generated using a HMI magnetogram on December 16, 2011 and used to reconstruct the magnetic field using the WindPredict-AW MHD code. The orange field lines connect the comet to the solar surface, with its trajectory traced out by the cyan curve. The arrow on the trajectory indicates the direction of motion along the orbit. The zoomed-in section in the bottom right shows the brightening event of interest in this paper, marked by a white arrow, as observed by STEREO-A/EUVI in the 304 Å band, triggered on December 16, 2011. The field line footpoints are also shown as yellow dots. In the upper right, we see the cometary tail in an SDO/AIA 171 Å image during the comet’s egress.