OPTICAL TRANSIENTS - AN OPEN QUESTION

The most significant results and conclusions from the first decade of the search for optical transients possibly related to gamma ray bursts are summarized and discussed. It is shown that these studies are heav ily affected by the presence of background (false) events. The sources of background in the search for brief optical flashes of astrophysica l origin are classified and discussed. Although many optical transient images can, after detailed analysis, be classified as background even ts, there remain several examples of detected objects which can neithe r be definitely confirmed nor excluded. A better knowledge of backgrou nd effect parameters is necessary in order to allow a better classific ation of the objects. The best method for the confirmation of a true a strophysical origin remains the detection on simultaneous exposures ta ken at widely separated stations.