Zoom on the filament branches as seen in Hα images acquired between August 22–29 by the Kanzelhöhe Solar Observatory and on August 30 by the Mauna Loa Observatory (no Kanzelhöhe image available from this day). This sequence shows the evolution of the two filament branches in the days before the eruption. Both filament branches show a strong clockwise inclination with respect to the meridian crossing it (dashed white line), one week before the eruption. This inclination progressively decreases with time, leaving both filament branches mostly aligned with the meridian one day before the eruption.