RED SUPERGIANTS IN THE LMC .1. BVRIJHK PHOTOMETRY, MAGNITUDES AND INTRINSIC COLORS

(BV)(J)(RI)(C) observations for 185 and additional JHK observations fo r 53 red supergiant candidates in the Large Magellanic Cloud (LMC) are presented. The data have been reduced discussing carefully the depend ence of effective wavelengths on the spectral energy distribution of t he star, which is very strong especially for the Cousins R band. Non-l inear colour dependences of transformation coefficients for the V magn itude and R-I colour have been taken into account. The mean error of t he BVRI data is 0.03 to 0.04 mag, while that of the JHK observations i s 0.02 mag. The data will be available at the Centre de Donnees astron omiques de Strasbourg (CDS). Because of the broad-band effects mention ed above, the reddening lines are strongly dependent on the spectral e nergy distributions of the stars. Infrared reddening lines are only sl ightly affected, as the effective wavelengths of these bands are almos t constant. Intrinsic colours and absolute magnitudes have been derive d applying new investigations of the foreground and internal reddening of the LMC. The (B-V)(0) and (V-R)(0) colours are redder than for gal actic red supergiants, while for (R-I)(0), (J-H)(0) and (H-K)(0) no di fferences have been found. With luminosities resembling those of galac tic Iab or Ia supergiants, the LMC objects are not more luminous than their galactic counterparts.