White mica wavelength position map for Nabesna, Alaska, derived from imaging spectrometer reflectance data

A map of the wavelength position of the white mica 2,200 nanometer (nm) Al-OH absorption feature was compiled for a region of Nabesna, Alaska, using HyMap™ reflectance data provided and described in this data release. White mica wavelength position was computed for each pixel with spectrally predominant muscovite or illite. The computation was made using a function of the USGS PRISM (Processing Routines in IDL for Spectroscopic Measurements) software (Kokaly, 2011), programmed in Interactive Data Language (IDL; Harris Geospatial Solutions, Broomfield, Colorado). The PRISM function applies linear continuum-removal (Clark and Roush, 1984) to the 2,200 nm feature and fits a parabola to three channels: the channel with the minimum value in continuum-removed reflectance and one channel on either side (Kokaly, 2011). PRISM uses the wavelength position of the axis of symmetry from the fitted parabola as the definition of wavelength value. The white mica wavelength values were output as a classification image, with classes in 1-nm (0.001-micron) increments.