The Pecina-Ceplecha functional as a tool to evaluate physical parameters of fireball bodies from observational data

Aims. We have investigated the sum of squares of differences between the theoretical and observed values of distances along the fireball path (the Pecina-Ceplecha functional) as a tool to evaluate physical parameters of fireball bodies from observational data. Methods. Using the functional to solve the fireball inverse problem, we verify its dependence of body disruption processes or gas flow conditions along the fireball path. We evaluate the functional directly after the numerical integration of the differential equations of motion and ablation for a single fireball-generating body and for a progressively disrupted one in the Earth’s atmosphere. We use a continuous-flow gas-dynamic model of interaction of the body with the atmosphere by the action of radiative and convective heating. We have minimized the functional varying the values of model parameters and tested the functional on the model fireballs and on those of the Prairie network. Results. A systematic course of the residuals with time obtained applying the functional to the observations of fireballs results not from a gross fragmentation, i.e. a sudden, instantaneous breakup of the fireball-generating body, but from the variability of the coefficient of heat transfer to the body along its path. Conclusions. Methods based on application of the functional may be a useful supplement to the locally-ballistic method of solving this problem as the actual values of the parameters sought for usually fall in between the two solutions.