Prototypical LPV-yso sources: Top panel: the LC of the source, error bars represent MAD(ΔS_imjd). Left middle panel: the corresponding periodogram in logarithmic scale (also plotted are the 99%, 95%, and 90% false probability levels, respectively: the green dot-dashed line, the cyan full line, and the red dashed line). Bottom left panel: the phase-folded light curve of the source using the best period fitted (also shows the corresponding value in days). Bottom right plot: the RGB image of the source using the Spitzer IRAC 3.6 μm, IRAC 4.0 μm, and the 24 μm MIPS band as blue, green and red, respectively. The VVV source is indicated by the blue circle and the green cross represents the MIPS co-ordinates. The contours of the RGB are in the interval of [Peak-5σ, Peak] from the ATLASGAL observation at 850 μm.