| Abstract : | Using multi-instrument and multi-wavelength observations, we studied a CME eruption that led to an intense geomagnetic storm on April 23, 2023. The eruption occurred on April 21, 2023, from solar active region 13283 near the disk center. The AR was in its decay stage, with fragmented polarities and a pre-existing long filament channel, a few days before the eruption. The study of magnetic field evolution suggests that the flux rope (filament) has been built up by monotonous helicity accumulation over several days, and further converging and canceling fluxes lead to helicity injection change, resulting in the unstable nature of the magnetic flux rope and its further eruption. Importantly, the CME morphology revealed that the MFR apex underwent a rotation of up 56\degree~in a clockwise direction owing to its positive helicity. The CME decelerates in the LASCO FOV and has a plane-of-sky velocity of 1226 km/s at 20 R$_\odot$. In the Heliospheric Imager FOV, the CME lateral expansion is tracked more than the earthward motion. {\bf This implies that the arrival time} estimation is difficult to assess. The in situ arrival of the ICME shock was at 07:30 UT on April 23 and a geomagnetic storm commenced at 08:30 UT. The flux rope fitting to the in situ magnetic field observations reveals that the MC flux rope orientation is consistent with its near Sun orientation, which has a strong negative Bz-component. The analysis of this study indicates that the near-Sun rotation of the filament during its eruption to the CME is the key to the negative Bz-component and consequently the intense geomagnetic storm. |
