Multi-band light curves of SN 2017ckj. A dashed vertical line is used to visually represent the reference epoch (MJD = 57843.9), which corresponds to the i-band observation maximum. The linear fit is applied to the light curve in each band, as indicated by the dashed lines. The epochs of our spectra are marked with vertical solid red lines on the top. In most cases, the errors associated with the magnitudes are smaller than the plotted symbol sizes.