Free Access
Fig. 2.

Exposure time of the stacked images centred on GRBs as a function of time. A clear trend towards lower exposures with time is apparent, reflecting the fact that GRBs were followed for longer times at the beginning of the Swift mission.
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.