In terms of bomb calorimetry, can one assume the temperature of the water surrounding the cmopartment is equal to the temperature within the compartment? If not, how would one determine T for the reaction occuring inside the compartment?

At equilibrium the two temperatures are the same; however, in the immediate vicinity, time wise, of pushing the button to react the materials, the T inside is considerably higher than that outside. What methods do you have to measure the temperature of the explosion.