Panels a)−c): sequence of AIA 131 Å images displaying a flux rope proxy tracked by a filament’s active material on 15 November 2013. The blue and red curves in panel a) are contours of corresponding negative and positive magnetic fields, respectively. Panels d)−f): corresponding HMI LOS magnetogram, AIA 171 Å and AIA 304 Å images. In panel d), the black curve outlines the general shape of the filament, and the red curve is the contour of brightness in panel c). An animation (5.mp4) of the 131 Å, 171 Å, and 304 Å channels shown in this figure is available in the online.