  Time-series photometry in I and J band of 57 inner Galactic late-type stars,
highly-probable red supergiant (RSG) stars, is here presented. 38% of the
sample presents significant photometric variations. The variations in I and J
band appear to be correlated, with DeltaI = DeltaJ x 2.2, DeltaI variations
ranging from 0.04-1.08 mag, DeltaJ variations from 0.03-0.52 mag. New short
periods (< 1000 d) could be estimated for 8 stars and range from 167-433 d.
This work confirms that the sample is not contaminated by large-amplitude
Asymptotic Giant Branch (AGB) stars. Furthermore, despite the large errors in
distance, the period-luminosity diagram suggests that the sample is populating
the same sequence as the known Galactic RSGs.
