Period-luminosity relation for classical cepheids. Estimating the intrinsic scatter

Published photoelectric and CCD photometric data for fundamental-mode Cepheids in the Large Magellanic Cloud are analyzed. The inferred scatter of the observed period-luminosity relation decreases with increasing quality of the light curves used. The observed scatter of the period-luminosity relations in the V and I-C bands is as low as 0(m).11 and 0(m).07, respectively, i.e., a factor of similar to 1.5 smaller than the lowest published estimates. This, in particular, suggests that the intrinsic scatter might be lower than previously believed.