V3890 Sgr light curve folded on the red giant oscillation period. This folded light curve has 105 J-band magnitudes from the SMARTS 1.3 m telescope in Chile, with each magnitude presented twice for phases 0–1 and 1–2. The folding period is 103.8 days and the epoch for the zero phase is JD 2454760. This period and amplitude are typical for oscillations on red giant stars. Note that the points are partly separated into individual strings, with each string having relatively little scatter. In this case, the overall scatter in this plot is due to cycle-to-cycle variations and not due to fast variations.