The total-to-selective extinction ratio determined from near IR photometry of OB stars

The paper presents an extensive list of the total to selective extinction ratios R calculated from the infrared magnitudes of 597 0 and B stars using the extrapolation method. The IR magnitudes of these stars were taken from the literature. The IR colour excesses are determined with the aid of artificial standards-Wegner (1994). The individual and mean values of total to selective extinction ratios R differ in most cases from the average value R = 3.10 +/- 0.05-Wegner (1993) in different OB associations. The relation between total to selective extinction ratios R determined in this paper and those calculated using the method of variable extinction and the Cardelli et al. (1989) formulae is discussed. The R values presented in this paper can be used to determine individual absolute magnitudes of reddened OB stars with known trigonometric parallaxes.