Folded light curve of 3I/ATLAS. The top panel shows the magnitude variation relative to the nightly median, which is, in the g band, 18.76, 18.79, and 18.49, respectively. The black line corresponds to a second-order sinusoidal curve fit with a period obtained from the PDM method. The bottom panel displays the data for a non-variable control star, also normalized by its median magnitude, demonstrating the lack of significant variation in the photometric calibration.