There is no time difference between AST - Atlantic Standard Time and Rochester, USA currently.
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AST - Atlantic Standard Time
Time zone offset: UTC/GMT -4
Please note that currently ADT (Atlantic Daylight Time) is observed inplace of AST in most regions.
ADT will change to AST when DST ends.
DST started on 10 March 2019
DST will end on 03 November 2019