SIMBAD references

In order to determine color excess in the uvby color system for fundamental-mode classical Cepheids, 29 Cepheids whose reliable distance values were compiled by Ngeow and Kanbur were selected as calibration stars. Then intrinsic photometric indices were calculated using given distances to derive a calibrated empirical relation between (b-y)₀ and period, [c₁], and [m₁] through a linear fit. This relation was used to determine color excesses of E(b-y) for 116 Cepheids, and the period-color relation was derived.