The left panel shows the LCs for the newly detected rotational variable 839 phase-folded to the dominant peak in its frequency spectrum and binned with a bin size of 0.02 in phase. The red points are from TESS Sector 19 and the blue points are from the ground-based observations. In the right panel, the corresponding frequency spectra for the respective LCs are given. We see the advantage of frequency resolution from TESS compared to the ground-based observations.