Optical Properties of Iron Silicates in the Infrared to Millimeter as a
  Function of Temperatures and Wavelength
  The Optical Properties of Astronomical Silicates with Infrared Techniques
(OPASI-T) program utilizes multiple instruments to provide spectral data over a
wide range of temperature and wavelengths. Experimental methods include Vector
Network Analyzer (VNA) and Fourier Transform Spectroscopy (FTS) transmission,
and reflection/scattering measurements. From this data, we can determine the
optical parameters for the index of refraction, \textit{n}, and the absorption
coefficient, \textit{k}. The analysis of the laboratory transmittance data for
each sample type is based upon different mathematical models, which are applied
to each data set according to their degree of coherence. Presented here are
results from iron silicate dust grain analogs, in several sample preparations
and at temperatures ranging from 5--300 K, across the infrared and millimeter
portion of the spectrum (from 2.5--10,000 \mic\ or 4,000--1 \wvn).
