In situ data obtained by ACE. Left: Proton density. Right: Measured velocity of the solar wind. Black vertical lines correspond to the location of the spacecraft along the Carrington longitude on the date of the event. The red vertical lines correspond to the measurements made when the spacecraft is at the Carrington longitude as determined by the BELLA-derived Parker spiral at 1 au. The red-shaded region corresponds to a ±10° around the red line to account for in situ measurement variability. Our measurements show a proton density of 4 ± 2.3 1/cc and a solar wind velocity of 500 ± 70 km s⁻¹.