EUCLID TELESCOPE PREVIEWS MILKY WAY CORE FOR NASA'S ROMAN SURVEY

The European Space Agency's Euclid space telescope has observed the centre of the Milky Way galaxy in an operation designed to support a forthcoming survey by NASA's Nancy Grace Roman Space Telescope. Euclid paused its primary cosmology mission for one day in March 2025 to capture imagery of a region that Roman will study in detail following its launch later in summer 2025. Jason Rhodes, a senior research scientist at NASA's Jet Propulsion Laboratory, stated that this coordination required substantial planning because it diverted Euclid from its standard operations. Rhodes, who serves as both the U.S. Euclid science lead and NASA JPL Roman project scientist, indicated that the combined observations would improve scientists' ability to map the galaxy and identify objects including isolated black holes and rogue planets.

Euclid's single observation covered approximately 5 square degrees of sky—equivalent to the area covered by roughly 25 full moons. The image has similar resolution to what Roman will achieve but lacks some colour detail that Roman's instruments will provide. Roman's Galactic Bulge Time-Domain Survey will focus on a smaller region of 1.7 square degrees, equivalent to approximately 8.5 full moons. Over its five-year primary mission, Roman will repeatedly image this smaller area to monitor changes in hundreds of millions of stars and other astronomical objects over short time periods.

The complementary observations from both telescopes are expected to yield significant scientific returns. Euclid's preview data will help scientists prepare for Roman's survey, which will provide one of the deepest views yet obtained of the galaxy's centre. The repeated imaging by Roman over time will reveal new planets and detect various other cosmic objects and phenomena through their observed changes.