Conversation so far:
When was Jan van Eyck a court painter?
In 1425 Jan van Eyck moved to Bruges and came to the attention of Philip the Good. His emergence as a collectable painter generally follows his appointment to Philip's court.
Where was Jan van Eyck a court painter at?
Jan Van Eyck served as official to John of Bavaria-Straubing, ruler of Holland, Hainault and Zeeland.

Question: What did he do as the court artist?
Self-contained rewrite: What did Jan van Eyck do as the court artist?