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The Joint Polar-orbiting Satellite System (JPSS)-3 Visible Infrared Imaging Radiometer Suite (VIIRS) has completed a large portion of its ground test program. The VIIRS series includes two sensors successfully operating on-orbit onboard the Suomi National Polar-orbiting Partnership (SNPP) and JPSS-1 satellites and a third sensor, currently integrated into the JPSS-2 satellite, is undergoing observatory level testing. VIIRS was designed to take high quality measurements of the Earths surface from low Earth orbit which are (or will be) used to generate a large set of environmental data products important in science. To ensure that the VIIRS instruments generate these high quality measurements once on orbit, each sensor undergoes an extensive ground test program at the component, sensor, and observatory levels. One of the important aspects of the instrument performance that needs to be characterized prior to launch is the response versus scan angle (RVS). This is the scan angle dependent change in reflectance of the rotating optics. On VIIRS, the only component of the rotating optics for which the angle of incidence changes with scan angle is the half angle mirror (HAM). The RVS was characterized for all bands, including reflective and thermal channels; results indicate that the sensor is behaving within expectations. Uncertainty estimates and atmospheric corrections for water vapor were also included in the analysis. Characterization of the RVS is critical to the retrieval of the TOA radiance and hence to ensure that the sensor performs with sufficient fidelity to provide the level of data quality that the science community demands. This work focuses on the performance of the JPSS-3 VIIRS RVS derived from instrument level ground testing, by the independent government team and compares that performance to previous builds.
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