I can't find Rigel on Tycho 2 catalogue
This frustrated me as well when I first used the Tycho-2 catalog. Not finding a well known bright star can be disconcerting. Quoting from http://heasarc.nasa.gov/W3Browse/all/tycho2.html


  Supplement-1 (not part of this HEASARC database but available at
  ftp://cdsarc.u-strasbg.fr/cats/I/259/suppl_1.dat.gz) lists stars from
  the Hipparcos and Tycho-1 Catalogues which are not in Tycho-2.


I only skimmed that file, but I think this might be the line you're looking for:

5331 01752 1|H|078.63446353|-08.20163919|    1.9|   -0.6|  0.6|  0.5|  0.7|  0.5| | 0.312|0.012| 0.283|0.010|999|T| 24436 


(the "-0.6" is the U-B color index, not the magntiude)