The Diffuse Interstellar Band at 8620 Ang: a good reddening tracer for GAIA

We report about a suprisingly good correlation between the equivalent width of the diffuse interstellar band (DIB) at 8620 Ang and the interstellar reddening. Such a correlation offers bright prospects in using the 8620 Ang DIB as a tracer of the exctinction through the Galaxy in the context of GAIA, approved Cornerstone mission by ESA.