1 Introduction

The optical constants of materials - refractive indices or dielectric permittivities - are widely used in astrophysics. They are input parameters required for any simulations of the light scattering by dust grains and the calculations of radiative transfer in dusty media (galaxies, interstellar clouds, circumstellar shells, protoplanetary disks, atmospheres of brown dwarfs). Since the 60's the volume of the data has been permanently growing and presently it is difficult to overlook the results obtained within about 40 years.

We attempted to collect and classify the data available and to create a place in the Internet for further accumulation of such data.