Comparisons of period measurements from Gaia DR3, AAVSO, and ASAS-SN. Left panel: fundamental-mode Per values of RSGs from Chatys et al. (2019) versus the Gaia DR3 Per values. Right panel: Gaia DR3 Per values of 12 late-type stars from Messineo & Brown (2019) versus Per values from the ASAS-SN survey. Chatys et al. (2019) do not include errors. The ASAS II/366/catalog in Vizier does not contain errors. The Gaia DR3 LPV pipeline table includes only frequency and errors on the frequency. . Errors on the Per values should be directly determined as the widths of peaks in the periodogram (Kiss et al. 2006). The plotted error bars for the Gaia Per values are