FIP periodogram for HD 176986. The dashed red line represents the 1% probability threshold for the periodic signal to be a false positive. We see three peaks exceeding this threshold, at period of 6.5 d, 16.8 d, and 61.4 d. The FIP level of 6.5 d and 16.8 d is cut at 11 because the numeric result gives an unphysical infinity. The peak at 61.4 d was not retrieved in the previous analysis and is an original result of our work.