Detection of the 2175 A Extinction Feature at z = 0.83

We determine the extinction curve in the z l = 0.83 lens galaxy of the gravitational lens SBS 0909+532 from the wavelength dependence of the flux ratio between the lensed quasar images ( z s = 1.38) from 3400 to 9200 Å. It is the first measurement of an extinction curve at a cosmological distance of... View More