eUDS: the SRG/eROSITA X-ray survey of the UKIDSS Ultra Deep Survey field. Catalogue of sources

Abstract

ABSTRACT The eROSITA X-ray telescope on board the Spectrum-Roentgen-Gamma (SRG) spacecraft observed the field of the UKIDSS Ultra-Deep Survey (UDS) in August–September 2019, during its flight to Sun–Earth L2 point. The resulting eROSITA UDS (or eUDS) survey was thus the first eROSITA X-ray imaging survey, which demonstrated the capability of the telescope to perform uniform observations of large sky areas. With a moderate single-camera exposure of 150 ks, eUDS covered ∼5 deg2 with the limiting flux ranging between 4 × 10−15 and 5 × 10−14 erg s−1 cm−2 in the 0.3–2.3 keV band. We present a catalogue of 647 sources detected at likelihood >10 (∼4σ) during the eUDS. The catalogue provides information on the source fluxes in the main energy band 0.3–2.3 keV and forced photometry in a number of bands between 0.3 and 8 keV. Using the deeper 4XMM-DR12 catalogue, we have identified 22 strongly variable objects that have brightened or faded by at least a factor of ten during the eROSITA observations compared to previous observations by XMM–Newton. We also provide a catalogue of 22 sources detected by eROSITA in the hard energy band of 2.3–5 keV.