A method of colour excess determination for classical cepheids

By use of the reddening free [m₁], [c₁], and indices data inuvby photometric system for three classical cepheids whose reddening values had been determined with the aid of photometry of field stars, three intrinsic relations of [m₁]–(b–y), [c₁]–(b–y), and –(b–y) have been established. It was shown that these three relations can be used to determine the colour excesses for other classical cepheids.