On the determination of carbon isotopic ratios in cool carbon stars II. Accuracy of the iso-intensity method for crowded spectra

de Laverny & Gustafsson (1998, Paper 1) questioned the iso-intensity method used by Ohnaka & Tsuji (1996) to derive carbon isotopic ratios in cool car bon stars. As a reply Ohnaka & Tsuji (1998) pointed out that the method cri ticized in Paper I differs from the original one and conclude that our resu lts are unreliable. No comparison of the two methods was. however, made. Th e iso-intensity method used in Paper I and OT96 do slighty differ in their definition. In investigating the consequences of this difference we have fo und that they are rather insignificant. We therefore confirm that the iso-i ntensity? method is not reliable when applied to crowded spectra of cool st ars. That reinforces the conclusions presented in Paper I.