I wouldn't say it's badly formatted, it's just formatted in fixed-width columns instead of whitespace-separated. Try something along the lines of this solution, using unpack:

#!/usr/bin/perl

use warnings;
use strict;

while (<DATA>) {
    my @words = unpack "A6A7A5A4A4A3A6A6A10A9A10", $_;
    s/^\s+// for @words;
    # Now @words contains your data
    print "@words\n";
}

__DATA__
 18884 alfCet  2.5 1.6 1.4 1U  43.3 241.9   22903.0    151.3     747.0
 18925 gamPer  2.9 0.7 0.6     54.6 319.3   14474.0    120.3     394.0
 19058  roPer  3.4 1.6 1.8 2U  57.5 293.4   22005.0    148.3    1122.0
 19275         4.9 0.0 0.1  C  43.7 346.9   18311.0    135.3    1700.0
 19356 betPer  2.1-0.1 0.0 3P  58.0 297.4   20842.0    144.4     417.0
 19373 iotPer  4.0 0.6 0.5  C  56.5 313.2   16303.0    127.7     510.0
 19476 kapPer  3.8 1.0 0.7  C  57.7 304.7   18094.0    134.5     707.0
 19656 omgPer  4.6 1.1 0.8     58.6 294.9   23508.0    153.3    1330.0
 19787 delAri  4.4 1.0 0.8     54.1 259.4   30779.0    175.4     524.0
 20150 zetAri  4.9 0.0 0.1  C  55.4 260.9   33579.0    183.2     638.0
 20336         4.8-0.1 0.0 1U  50.0 338.0   13931.0    118.0     453.0
 20468         4.8 1.5 1.1     59.9 284.2   22993.0    151.6    2761.0
 20630 kapCet  4.8 0.7 0.6 1P  45.9 237.1   24642.0    157.0     463.0
 20644         4.5 1.5 1.2 1M  59.4 274.0   32184.0    179.4     729.0
 20677    Per  5.0 0.0 0.1  C  60.1 302.5   20469.0    143.1     392.0
 20902 alfPer  1.8 0.5 0.5 1M  58.8 315.2   16320.0    127.7     430.0
 21120 omiTau  3.6 0.9 0.7  C  50.7 241.9   36123.0    190.1    3694.0

 21278         5.0-0.1 0.0  C  59.6 314.2   16296.0    127.7     464.0
 21291         4.2 0.4 0.4 1P  54.4 331.8   14214.0    119.2     373.0
 21364  xiTau  3.8-0.1 0.0 2U  51.6 242.2       0.0      0.0       0.0
 21389         4.5 0.6 0.5 1U  55.1 330.4   13585.0    116.6     386.0
 21428    Per  4.7-0.1 0.0  D  59.7 315.1       0.0      0.0       0.0
[download]

-- Mike

--
just,my${.02}