my @index;
while (<BIGLOG>){
    my $offset = tell BIGLOG; ### This offset is the start of the *next* line!
    my $epoch = ( /^\s*#/ or /^\s\n/ or $_ !~ /^\s*\d/ ) ? 0 
        : Mktime( unpack 'A4xA2xA2xA2xA2xA2', $_  );
    push @index, pack 'NN', $epoch, $offset;
}