Magnitude and colour distribution of carbon stars. Left panels: vertical black dashed line shows the upper magnitude limit of the data processed by ESP-ELS. Upper panels: all the targets belonging to the golden sample of carbon stars are taken into account. Other panels: distributions obtained for the known MW (Alksnis et al. 2001), LMC (Kontizas et al. 2001), and SMC (Morgan & Hatzidimitriou 1995) carbon stars are shown in blue. In orange, we show the distribution of the targets in common with the sample we propose in this work.