This dataset includes Level 1B (L1B) data products from the MODIS/ASTER Airborne Simulator (MASTER) instrument. The spectral data were collected during three flights aboard a DOE B-200 aircraft over Phoenix, Arizona, and the Jornada Experimental Range (JORNEX) in New Mexico, U.S., on 2003-04-28 to 2003-05-02. These data were used to evaluate the Temperature Emissivity Separation (TES) algorithm for extracting land surface temperature and emissivity data from thermal infrared data from ASTER. This deployment was coordinated by the U.S. Department of Energy's Remote Sensing Laboratory (RSL) located at Nellis Air Force Base near Las Vegas, Nevada. Data products include L1B georeferenced multispectral imagery of calibrated radiance in 50 bands covering wavelengths of 0.460 to 12.879 micrometers at approximately 10-meter spatial resolution. The L1B file format is HDF-4. In addition, the dataset includes flight paths, spectral band information, instrument configuration, ancillary notes, and summary information for each flight, and browse images derived from each L1B data file.