Others already suggested some cleanup for your regex, but I'd suggest to comment the regex a bit using the x modifier (starting from GrandFather's version):

   m<
      (                 # Start of capture #1
         [A-Z][a-z]{2}  # Month name
         \s
         \d{2}          # Day
         \s
         \d{2}:\d{2}    # Hour:Minutes
      )                 # End of capture #1
      \s
      (/.+\.Z)          # Capture #2: File name
    >x;                 # End of regex, note 'x' modifier
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Of course the actual indentation and commenting style is at your will.