Free Access
Fig. 4

The ON-source and normalized background distribution of θ2. The denotations are the same as in Fig. 2. A clear excess with a significance of more than 25 standard deviations for a source at the position of PKS 2155-304 is found.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.