The 2019-2020 ROMAN Exoplanet Imaging Data Challenge (www.exoplanetdatachallenge.com) is a successful community engagement effort led by the Turnbull Science Investigation Team. It launched in October 2019 and ran for 8 months. This Data Challenge (DC) was a unique opportunity for exoplanet scientists of all backgrounds and experience levels to get acquainted with realistic simulated data. With a new contrast regime (10^-8 to 10^-9), the ROMAN CGI (the technology demonstration coronagraph instrument) data enables to unveil planets down to the Neptune-mass in reflected light. Participating teams had to recover a hidden exoplanetary system combining 15 years of simulated precursor radial velocity data with 6 imaging epochs throughout the mission: 4 epochs with the Hybrid Lyot Coronagraph (HLC) and 2 epochs with the Star Shade assuming a Rendez-Vous occurs down the road. They had to perform accurate astrometry and orbital fitting and determine the mass of any planet hidden in the data. It also involved PSF subtraction techniques and post-processing and other astrophysics hurdles to overcome such as contamination sources (stellar, extragalactic and exozodiacal light). We organized 4 tutorial “hackathon” events in 2019 to get as many people on-board. This precious training material was improved along the duration of the challenge and will remain online. The DC proved to be an excellent way to engage with the intricacies of the first mission to perform wavefront control in space, as a pathfinder to future flagship missions with high contrast. It also generated a lot of positive interactions between open source package owners and a diverse crowd of young exoplanet scientists running them. As a community we are a few steps closer to being ready to analyze real CGI data! In this lecture I will show how the DC was designed and organized, its potential and our preliminary analysis of the results, anecdotes and feedback from anonymous participants.
