Trajectory and orbit of the Tunguska meteorite revisited

A critical survey is presented of all determinations of the azimuth and inc lination of the Tunguska meteorite's trajectory based either on eyewitness testimonies or on the mathematical treatment of the forest-leveling field i n the area of the catastrophe. The eyewitness testimonies collected in the neighborhood of the Nizhnyaya Tunguska River indicate the most probable azi muth of the trajectory projection to be 104 degrees from the north to the e ast, which is close to the most recent azimuth estimate from the forest-lev eling field, 99 degrees. For the most part of the trajectory, its inclinati on could not exceed 15 degrees. However, it is seen from aerodynamic calcul ations that the combined action of the gravity field and a nonzero aerodyna mic lift could increase the inclination to 40 degrees as the end of the tra jectory was approached. Meteoroid orbits are calculated for a broad family of trajectories with azimuths ranging from 99 degrees (Fast et al., 1976) t o 137 degrees (Krinov, 1949) and geocentric velocities ranging from 25 to 4 0 km/s. Orbits with large azimuth values (120 degrees and larger) are shown to belong to the asteroidal type. They are succeeded by the orbits of shor t-period and long-period comets, whereas very small azimuth values and larg e geocentric velocities correspond to the region of hyperbolic orbits. Cert ain restrictions on the possible trajectory azimuths and geocentric velocit ies of the Tunguska body are imposed by this study.