Evolution of SXP31.0 during the 2025 outburst based on Swift/XRT, NuSTAR, and SRG/ART-XC observations. The light curve in the 4–12 keV energy range is shown at the top panel. The gray points show the CGRO/BATSE 20–50 keV pulsed luminosity from the 1998 outburst, overplotted for comparison. Along the time axis it was placed arbitrarily, and the luminosity was scaled by a factor of 0.45. The spin period (see Table 2) is shown at the bottom panel.