Multi-instrument background-subtracted X-ray light curves of J0840 between 2020 February 5−10, binned at 800 s. The grey shaded region in the top panel indicates the confidence interval (at 3σ) for the quiescent Swift/XRT net count rate computed by stacking all observations performed since 2020 February 10 (see Table 1). In most cases, the marker size is larger than the error bars.