Wasp - 10 b is a very interesting transiting extrasolar planet .
Although its transit is very deep , about 40 mmag , there are very different estimates of its radius in the literature .
We present new photometric observations of four complete transits of this planet .
The whole event was detected for each transit and the final light curve consists of more than 1500 individual CCD exposures .
We determine the following system parameters : planet to star radius ratio R _ { \mathrm { p } } / R _ { * } = 0.168 \pm 0.001 , star radius to semimajor axis ratio R _ { * } / a = 0.094 \pm 0.001 and inclination i = 87.3 \pm 0.1 deg .
Assuming that the semimajor axis is 0.036 9 \pm ^ { 0.0012 } _ { 0.0014 } AU ( Christian et al .
2009 ) , we obtain the following radius of the planet R _ { \mathrm { p } } = 1.22 \pm 0.05 R _ { \mathrm { J } } , and radius of the star R _ { * } = 0.75 \pm 0.03 .
The errors include the uncertainty in the stellar mass and the semimajor axis of the planet .
Surprisingly , our estimate of the planet radius is significantly higher ( by about 12 percent ) than the most recent value of Johnson et al .
( 2009 ) .
We also improve the orbital period P _ { \mathrm { orb } } = 3.092 731 \pm 1 \times 10 ^ { -6 } days and estimate the average transit duration T _ { \mathrm { D } } = 0.097 4 \pm 8 \times 10 ^ { -4 } days .