my $filename = 'Facs_Data.txt';
open my $fh, '<', $filename
    or die "Couldn't open '$filename': $!";

my @lines = map  { /:([^\s]+)/ ? $1 : () } # take the stuff between the : and the first blank
            grep { /Acct:/ } <$fh>; # Read a file line by line and select the lines matching Acct:

# do whatever with the values in @lines
print "$_\n" for @lines;