SATLASX-ray · Space
eROSITA
extended ROentgen Survey with an Imaging Telescope Array
PausedPaused since 26 February 2022.
In safe mode since 26 February 2022. The German half of its first all-sky survey (eRASS1) was released in January 2024, and cumulative catalogues from the first three surveys (eRASS:3, nearly two million sources) in July 2026.
Seven Wolter-Igrazing-incidence opticsX-rays reflect only at angles of a degree or less, so X-ray telescopes use nested shells of paraboloid and hyperboloid mirrors seen almost edge-on (the Wolter-I design). More shells add effective area; figure accuracy sets the PSF. mirror modules of 54 nested shells each, with pn-CCDCCDCharge-coupled device: a silicon pixel array that stores photo-electrons and shifts them to a readout amplifier. The workhorse optical detector; in X-rays, each photon's charge also measures its energy. cameras, scanned great circles through the ecliptic poleseclipticThe plane of Earth's orbit projected on the sky; the Sun, Moon and planets stay close to it. Solar-system bodies and zodiacal light concentrate there, and spacecraft that must keep the Sun at a fixed angle often observe in strips perpendicular to it, so the ecliptic poles get the deepest coverage. to survey the whole sky every six months. The first pass alone (eRASS1) catalogued about 930,000 sources in the German half of the sky: AGN, galaxy clusters, coronally active stars and compact binaries. Built by MPE for the Russian–German Spektr-RG.
- Operator
- MPE, IKI
- Orbit
- Sun–Earth L2, aboard Spektr-RG
- Passband
- 0.2 keV – 8 keV
- Launch
- 13 July 2019
- Placed in safe mode
- 26 February 2022
Passband
Sky coverage
All-sky scanningall-sky surveyObserving the entire celestial sphere to uniform depth, typically by scanning great circles or tiling fields. Produces catalogues and maps others select targets from. survey from L2Lagrange pointA point where the gravity of two bodies and the orbital motion balance. Sun–Earth L2, 1.5 million km beyond Earth, keeps Sun, Earth and Moon on one side: a stable thermal environment for passive cooling and an unobstructed view of most of the sky., which completed four full passes and part of a fifth before safe mode; exposure is deepest at the ecliptic poles. Public data cover the German half, Galactic longitudeGalactic coordinatesA frame aligned with the Milky Way: latitude b is measured from the Galactic plane and longitude l from the direction of the Galactic centre. Natural for anything concentrated in the disc. 180°–360°.
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Verified 15 November 2026.