  We present VRI spectrophotometry of 1003 Main-Belt Asteroids (MBAs) observed
with the Sutherland, South Africa, node of the Korea Microlensing Telescope
Network (KMTNet). All of the observed MBAs were serendipitously captured in
KMTNet's large 2deg $\times$ 2deg field of view during a separate targeted
near-Earth Asteroid study (Erasmus et al. 2017). Our broadband
spectrophotometry is reliable enough to distinguish among four asteroid
taxonomies and we confidently categorize 836 of the 1003 observed targets as
either a S-, C-, X-, or D-type asteroid by means of a Machine Learning (ML)
algorithm approach. Our data show that the ratio between S-type MBAs and
(C+X+D)-type MBAs, with H magnitudes between 12 and 18 (12 km $\gtrsim$
diameter $\gtrsim$ 0.75 km), is almost exactly 1:1. Additionally, we report
0.5- to 3-hour (median: 1.3-hour) light-curve data for each MBA and we resolve
the complete rotation periods and amplitudes for 59 targets. Two out of the 59
targets have rotation periods potentially below the theoretical zero cohesion
boundary limit of 2.2 hours. We report lower limits for the rotation periods
and amplitudes for the remaining targets. Using the resolved and unresolved
light curves we determine the shape distribution for this population using a
Monte Carlo simulation. Our model suggests a population with an average
elongation $b/a = 0.74\pm0.07$ and also shows that this is independent of
asteroid size and taxonomy.
