SRG/ART-XC Galactic Plane Survey Near Galactic Longitude $$\boldsymbol{l\simeq 20^{\circ}}$$: Catalog of Sources

We present a catalog of sources detected by the Mikhail Pavlinsky ART-XC telescope onboard the SRG space observatory during the observations of the Galactic plane region near a longitude $$l\simeq 20^{\circ}$$ (L20 field) in October 2019. The L20 field was observed four times in the scanning mode, which provided a uniform coverage of the sky region with a total area of $${\simeq}24\text{ deg}^{2}$$ with a median sensitivity of $$8\times 10^{-13}$$ erg s $${}^{-1}$$ cm $${}^{-2}$$ (at 50 $$\%$$ detection completeness) in the 4–12 keV energy band. As a result, we have detected 29 X-ray sources at a statistically significant level, 11 of which have not been detected previously by other X-ray observatories. Preliminary estimates show that four of them can presumably be extragalactic in nature. We also show that the source SRGA J183220.1 $$-$$ 103508 (CXOGSG J183220.8 $$-$$ 103510) is most likely a galaxy cluster containing a bright radio galaxy at redshift $$z\simeq 0.121$$ .