We derive the extinction curve towards the Galactic Center from 1 to 19 \mu m. We use hydrogen emission lines of the minispiral observed by ISO-SWS and SINFONI .
The extinction free flux reference is the 2 cm continuum emission observed by the VLA .
Towards the inner 14 ^ { \prime \prime } \times 20 ^ { \prime \prime } we find an extinction of A _ { 2.166 \mu \mathrm { m } } = 2.62 \pm 0.11 , with a power-law slope of \alpha = -2.11 \pm 0.06 shortward of 2.8 \mu m , consistent with the average near infrared slope from the recent literature .
At longer wavelengths , however , we find that the extinction is grayer than shortward of 2.8 \mu m. We find it is not possible to fit the observed extinction curve with a dust model consisting of pure carbonaceous and silicate grains only , and the addition of composite particles , including ices , is needed to explain the observations .
Combining a distance dependent extinction with our distance independent extinction we derive the distance to the GC to be R _ { 0 } = 7.94 \pm 0.65 kpc .
Towards Sgr A* ( r < 0.5 ^ { \prime \prime } ) we obtain A _ { H } = 4.21 \pm 0.10 , A _ { Ks } = 2.42 \pm 0.10 and A _ { L ^ { \prime } } = 1.09 \pm 0.13 .