Re-analysis of three archival optical objects on Odessa plates

With the knowledge of distinct differences between real stellar images and typical emulsion defects on archival astronomical plates (Greiner et al. 1990) we have investigated the object discovered by Moskalenko et al. (1989) on two simultaneously exposed Odessa Observatory plates. We conclude that the object on the blue plate is an emulsion defect, and that the object on the V plate is a grain cluster which is accidentally located on the same projected sky location as the defect on the B plate. Additionally, we have re-analyzed two objects found on plates from 1963 September 15 and 1965 September 24, respectively (Moskalenko et al. 1992). The 1963 object is found to be a plate defect whereas the 1965 object does not show hints for a defect nature. Finally, we re-estimate the optical flash rate from γ-ray bursters based on the investigation of the ukrainian and tadzhikistan plate collections