Imaging of Close Encounters With Solar Transients

On 2021 April 24, during the eighth close perihelion passage of Parker Solar Probe (PSP) by the Sun, the WISPR white-light imagers on PSP observed a series of transients that pass rapidly through the fields of view of both the inner and outer telescopes, WISPR-I and WISPR-O, respectively. In-situ data from PSP indicates that one or more of these transients hit the spacecraft. We here analyze the available images of the transients to determine their trajectories, in order to determine which of them hit PSP. Crucial supporting data is provided by the COR2 coronagraph on STEREO-A. The COR2-A imaging shows an unstable streamer belt in this time period, with lots of small transients erupting on both limbs of the Sun. For the limb relevant to PSP’s location, we identify six distinct transients, which we connect to individual fronts in the WISPR images. Combining the COR2 and WISPR data allows for a reconstruction of the transient speeds and directions.