Light curves of Betelgeuse for the last 15 years: the top panel shows the AAVSO optical (V-band) light curve; the bottom panel shows the JCMT/SCUBA-2 450 μm (green points) and 850 μm (red points) light curve constructed using both archival and newly obtained observations. Here we also show the APEX/LABOCA 870 μm light curve (purple squares) obtained from archival data. While not used in the fitting we also show the single ALMA 890 μm data point (brown triangle) from O’Gorman et al. (2017), to illustrate the consistency. The gray dashed line indicates the beginning of the dimming of the recent pulsation cycle. The inset panel shows a zoomed-in version of the JCMT/SCUBA-2 light curve with the corresponding UT date for each observation. All error bars indicate 1σ uncertainties including the uncertainty on the absolute calibration.