The Prototype Hyperspectral Infrared Imager Thermal Infrared Radiometer (PHyTIR) is the primary instrument aboard the ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) and measures the thermal infrared brightness temperatures (BT) of plants. From its mounting aboard the International Space Station, PHyTIR provides data with 38-m in-track by 69-m cross-track spatial resolution and predicted temperature sensitivity of ≤0.1 K. A double-sided scan mirror, rotating at a constant 25.4 rpm, allows the telescope to view a 53°-wide nadir cross-track swath as well as two internal blackbody calibration targets every 1.29 seconds. Spectral filters on the focal plane define 5 spectral bands in the 8-12.5 μm range and an additional band at 1.6 um for geolocation and cloud detection (six bands total).
