Interstellar extinction toward symbiotic stars

Using diffuse interstellar bands (DIBs) at 5780 Å, 5797 Å and 6613 Å, visible in the high resolution spectra, and measuring their equivalent widths, we estimate the interstellar extinction toward seven symbiotic stars. We find $E_{B-V}$= $1.28 ± 0.10$ for AS 289, $E_{B-V}$= $1.55 ± 0.10$ for BI Cru, $E_{B-V}$= $0.63 ± 0.10$ for HD 330036, $E_{B-V}$= $0.33 ± 0.05$ for V2756 Sgr, $E_{B-V}$= $0.30 ± 0.05$ for V2905 Sgr, $E_{B-V}$= $1.52 ± 0.11$ for V417 Cen, $E_{B-V}$= $0.81 ± 0.10$ for PN Sa 3-22. The derived values are in agreement with the extinction through the Galaxy.