A method of operating a microlithographic projection exposure apparatus (10) includes: providing a wave front deviation (50) of the projection lens and determining a control command (42) including travels for the manipulator system for correcting the wave front deviation using a model (60). The model describes the wave front deviation as a function of the travel variables and has a group of offset coefficients (62), which are independent of the travel variables, a group of linear coefficients (64), which are each attributed to one of the travel variables to the power of one, and a group of quadratic coefficients (66), which are each attributed to a product of two of the travel variables or to a square of one of the travel variables. The offset coefficients (62) are calibrated more frequently than are the linear coefficients (64).