Diffuse interstellar band at 862 nm as a reddening tracer for GAIA

We investigate the plausibility of using diffuse interstellar band at 862 nm for tracing interstellar extinction with the ESA's astrometric space mission GAIA. For this purpose we perform numerical tests to simulate the conditions of real observations, covering a wide range of stellar parameters and different amounts of interstellar extinction. Our simulations indicate that with the present Radial Velocity Spectrometer setup the uncertainty in color excess of sigma(E(B-V)) less than or equal to 0.05 can be achieved only for the interstellar reddening tracers brighter than V similar to 13. None of the plausible tracers can provide accurate color excesses (sigma(E(B-V)) less than or equal to 0.05) at the distances beyond 2 kpc. We therefore conclude that with the currently planned instrumentation onboard GAIA this method can not be used as a stand-alone approach for probing interstellar extinction on the Galactic distance scales within the framework of the GAIA mission.