Perhaps you could make use of the flip-flop operator (..) to push lines onto your @data array from the occurence of the "Parameter" line through to the end of file. Given this data file:-

Header Line 1
Header Line 2
Third Header Line
Parameter line here
and the
rest of the
data follows
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This code:-

use strict;
use warnings;

my $dataFile = q{spw850417.data};
open my $dataFH, q{<}, $dataFile
   or die qq{open: < $dataFile: $!\n};

my @data;

while ( <$dataFH> )
{
    push @data, $_ if m{^Parameter} .. eof $dataFH;
}

close $dataFH
   or die qq{close: < $dataFile: $!\n};

print @data;
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Gives this output:-

Parameter line here
and the
rest of the
data follows
[download]

I hope this is something along the lines of your requirement.