Orbit, emission spectrum, and photometric analysis of two flickering sporadic fireballs

We present the observations of two fireballs that exhibit fast and quasi-periodic brightness variations along their atmospheric path. This phenomenon, which is known as “flickering”, is associated to the entry of spinning non-spherical meteoroids into the atmosphere. Both bolides were imaged in the framework of the continuous fireball monitoring and meteor spectroscopy campaigns organized by the SPanish Meteor Network (SPMN) in 2012. Their atmospheric trajectory, radiant, and orbit were calculated. The preatmospheric mass and tensile strength of the parent meteoroids were also estimated, and the rotation of these bodies analyzed on the basis of the photometric behavior of the bolides. Although small (less than 80 grams), a non-zero terminal mass was determined for both events. The emission spectra produced during the ablation of the meteoroids in the atmosphere are also discussed.