Sky mapper

A few weeks before Webb’s arrival at L2, Gaia experts Uli Bastian of Heidelberg University (Germany) and Francois Mignard of Nice Observatory (France) realised that during Gaia’s continuous scanning of the entire sky, its new neighbour at L2 should occasionally cross Gaia’s fields of view.

Gaia is not designed to take real pictures of celestial objects. Instead, it collects very precise measurements of their positions, motions, distances, and colours. However, one part of the instruments on board takes a sort of sky images. It is the ‘finder scope’ of Gaia, also called the sky mapper.