Euclid, one of the most precise and stable space telescopes ever built, was launched on 1 July 2023. During its first months in space, teams across Europe turned on, tested, and prepared the mission for routine science observations. However, these ‘routine’ science observations are no piece of cake.
50 000 galaxies in one shot
One of Euclid’s strengths is that it can observe a large area of the sky in one shot. This is crucial for a mission whose primary objective is to map more than one third of the sky in six years.
“Thanks to its wide-eyed look at the cosmos, and its long exposure time and sensitivity, the number of galaxies that Euclid can see in one pointing is huge,” explains Roberto Scaramella, Euclid survey scientist at the National Institute for Astrophysics (INAF) in Italy, and lead of the consortium survey group since the beginning of the mission.
“To study the individual distortions of galaxies by dark matter, we need to observe at least 1.5 billion galaxies. Euclid will observe the shapes of around 50 000 galaxies with the needed accuracy in one shot, and will spot many more faint ones,” adds Roberto.
However, soon after turning Euclid’s instruments on for the first time, the team realised that the entire survey needed to be re-designed.
Looking ahead at Euclid’s first survey year
Today, Euclid officially started its survey. The telescope is currently scheduled to observe a patch of 130 square degrees – more than 500 times the area of the full Moon – over the course of the next 14 days. This patch is in the direction of the constellations of Caelum and Pictor in the Southern Hemisphere.
In the coming year, Euclid will cover around 15% of its survey. This first year of cosmology data will be released to the community in summer 2026. A smaller data release of deep field observations is foreseen for spring 2025.
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