  The exoplanet HD 118203 b, orbiting a bright (V = 8.05) host star, was
discovered using the radial velocity method by da Silva et al. (2006), but was
not previously known to transit. TESS photometry has revealed that this planet
transits its host star. Five planetary transits were observed by TESS, allowing
us to measure the radius of the planet to be $1.133 \pm 0.031 R_J$, and to
calculate the planet mass to be $2.173 \pm 0.078 M_J$. The host star is
slightly evolved with an effective temperature of $T_{\rm eff} = 5692 \pm 83$ K
and a surface gravity of ${\rm log}(g) = 3.891 \pm 0.019$. With an orbital
period of $6.134980 \pm 0.000038$ days and an eccentricity of $0.316 \pm
0.021$, the planet occupies a transitional regime between circularized hot
Jupiters and more dynamically active planets at longer orbital periods. The
host star is among the ten brightest known to have transiting giant planets,
providing opportunities for both planetary atmospheric and asteroseismic
studies.
