Multiwavelength light curve of J012026. Top panel: X-ray evolution in the 0.2–2.3 keV band (empty triangles correspond to upper limits). Middle panel: WISE W1 and W2 light curve presented in AB magnitudes. Bottom panel: Difference-photometry light curve for the ATLAS o and c filters in μJy. The vertical dashed lines indicate the eRASS2 discovery. The numbered ticks at the top of the plot indicate the epochs at which optical spectroscopy was collected (see Sect. 5).