On the optical extinction and distance of GRS 1915+105

Based on new millimeter and radio observations, we reevaluate the total hydrogen column density along the line of sight to the microquasar GRS 1915+105 to N_H =(3.5 ± 0.3)× 10²² cm^-2. Our value is consistent with the one derived from X-ray measurements, namely (3.8 ± 0.3)×10²² cm^-2 (Ebisawa et al. \cite{ebisawa}). Using the empirical law between the visual extinction and the total column density of hydrogen, A_v is found to 19.6 ± 1.7 mag. This result is ∼ 7 mag lower than previously thought, and therefore, a reevaluation of infrared fluxes after derredening is needed. The revisited kinematic study allows to give a lower limit to the distance of GRS 1915+105 , namely 6.0 kpc. Taking into account the most accurate upper limit of distance inferred from radio data (11.2 ± 0.8 kpc, Fender et al. \cite{fender2}) as well as this lower limit, this implies a distance of 9.0 ± 3.0 kpc.