Digital Processing on Comets

Several digital techniques have been used to remove large-scale background variations caused by manufacturing and technology of the photographic processing on old photographic plates ORWO ZU-21. Suppression of these large-scale background variations improved the study of large-scale phenomena in cometary plasma tails and the determination of the solar wind characteristics. The results obtained from five images of the comet Bradfield 1987 XXIX have been compared. It has been shown that the simple digital techniques used were applicable also to photographic plates with images of lesser quality. They may be utilized in the treatment of old photographic plate archives.