Improved methods for calibrating and characterizing the CCD array based off-nadir tiltable advanced solid-state array spectroradiometer (ASAS) were developed and applied. Sensor characteristics such as radiometric sensitivity, polarization sensitivity, signal-to-noise-ratio, temperature sensitivity, spectral bandpass, spectral distortion, spatial distortion, and spatial resolution were measured. Radiometric sensitivity, array temperature sensitivity, and signal-to-noise were measured using a barium sulfate coated integrating hemisphere whose output calibration is traceable to NIST. Polarization sensitivity was measured for 48 of 62 spectral bands across all 512 spatial pixels. Spectral bandpass and spectral distortion were measured using a 0.5 meter doublepass monochromator. Spatial resolution (given as the modulation-transfer-function -- MTF) and distortion were measured using a combination of monochromatic collimated light to directly measure the point-spread-function (PSF) and the edge spread function (ESF) derived from actual image data. The MTF obtained using the two techniques are compared. Potential improvements to the test setups and methods are described.