Abstract

The eROSITA X-ray telescope is the soft X-ray instrument on the Spectrum-Roentgen-Gamma (SRG) mission, launched successfully in 2019. Before the start of its four-year all-sky survey, eROSITA observed a number of calibration and performance verification targets. The German eROSITA team will shortly be releasing its data in an early data release. I will report on a number of results from these data focusing on galaxy clusters. These observations include a 140 square-degree survey of the sky containing a number of clusters and superclusters, a detailed mosaic of a galaxy cluster pair, and deep observations of relaxed and merging clusters. With its wide field of view and well-characterised background eROSITA is perfect for detecting clusters and other faint structures which would be hard to find using other X-ray telescopes. These results provide a number of insights about cluster populations and astrophysical processes.