We determine the extinction curve in the z _ { l } = 0.83 lens galaxy of the gravitational lens SBS0909+532 from the wavelength dependence of the flux ratio between the lensed quasar images ( z _ { s } = 1.38 ) from 3400 to 9200Å .
It is the first measurement of an extinction curve at a cosmological distance of comparable quality to those obtained within the Galaxy .
The extinction curve has a strong 2175Å feature , a noteworthy fact because it has been weak or non-existent in most estimates of extinction curves outside the Galaxy .
The extinction curve is fitted well by a standard R _ { V } = 2.1 \pm 0.9 Galactic extinction curve .
If we assume standard Galactic extinction laws , the estimated dust redshift of z = 0.88 \pm 0.02 is in good agreement with the spectroscopic redshift of the lens galaxy .
The widespread assumption that SMC extinction curves are more appropriate models for cosmological dust may be incorrect .