  Using simultaneous multi-filter observations during the transit of an
exoplanet around a K dwarf star, we determine the temperature of a starspot
through modeling the radius and position with wavelength-dependent spot
contrasts. We model the spot using the starspot modeling program STarSPot
(STSP), which uses the transiting companion as a knife-edge probe of the
stellar surface. The contrast of the spot, i.e. the ratio of the integrated
flux of a darker spot region to the star's photosphere, is calculated for a
range of filters and spot temperatures. We demonstrate this technique using
simulated data of HAT-P-11, a K dwarf (T = 4780 K) with well-modeled starspot
properties for which we obtained simultaneous multi-filter transits using LCO's
MuSCAT3 instrument on the 2-meter telescope at Haleakala Observatory which
allows for simultaneous, multi-filter, diffuser assisted high-precision
photometry. We determine the average (i.e. a combination of penumbra and umbra)
spot temperature for HAT-P-11's spot complexes is 4500 K $\pm$ 100 K using this
technique. We also find for our set of filters that comparing the SDSS g' and
i' filters maximizes the signal difference caused by a large spot in the
transit. Thus, this technique allows for the determination of the average spot
temperature using only one spot occultation in transit and can provide
simultaneous information on the spot temperature and spot properties.
