Observing the solar corona from a formation-flying mission. First results of Proba-3/ASPIICS

Abstract: We report the first results from observations of the solar corona by the ASPIICS coronagraph aboard the Proba-3 mission. ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun) is a giant coronagraph consisting of the telescope mounted aboard one of the mission's spacecraft and the external occulter placed on the second spacecraft. The two spacecraft separated by around 144 m fly in a precise formation up to 5.5 hours at a time, which allows coronal observations in eclipse-like conditions, i.e. close to the limb (typically down to 1.099 Rs, occasionally down to 1.05 Rs) and with very low straylight. ASPIICS observes quasi-stationary structures, such as coronal loops, streamers, quiescent prominences, and a variety of dynamic phenomena: erupting prominences, coronal mass ejections, jets, slow solar wind outflows, coronal inflows. In particular, weak, widespread and persistent small-scale outflows and inflows between 1.3 and 3 Rs are observed at a high spatial (5.6 arcsec) and temporal (30 s) resolution for the first time, expanding the range of scales at which the variable slow solar wind is observed to form.