Light curve of a Cepheid variable star with a period of ~3.4 days, as seen by EROS-2and OGLE. The left plots show the magnitude measurements as a function of time in days (mjd - 49999.5) over more than ten years, and the right plots show the magnitude measurements folded over a single period. The top plots show the measurements in the R_eros and I_ogle bands, and B_eros and V_ogle are shown in the bottom panels. OGLE data for this Cepheid were obtained from https://ogledb.astrouw.edu.pl/~ogle/OCVS/.