The Near Real Time (NRT) VIIRS/JPSS2 Day/Night Band Resolution Terrain Corrected Geolocation 6-Min L1 Swath 750m, short-name VJ203DNB_NRT is the Joint Polar-orbiting Satellite System-2 (JPSS-2/NOAA-21) platform-based NASA VIIRS L1 terrain-corrected geolocation product, and contains the derived line-of-sight (LOS) vectors for the single panchromatic Day-Night band (DNB). The geolocation algorithm uses a number of inputs that include an Earth ellipsoid, geoid, and a digital terrain model along with the SNPP platform's ephemeris and attitude data, and knowledge of the VIIRS sensor and satellite geometry. It provides geodetic coordinates (latitude and longitude), and related parameters for each VIIRS L1 pixel. The VJ203DNB product includes geodetic latitude, longitude, surface height above the geoid, solar zenith and azimuth angles, lunar zenith and azimuth angles, sensor zenith and azimuth angles, land/water mask, moon illumination fraction and phase angle, and quality flag for every pixel location.

The J2 VIIRS geolocation underwent an on-orbit validation. Geolocation errors of about 350 m in the along-scan direction and about 165 m in the along-track direction were corrected for the image-resolution bands and moderate-resolution bands. The Day-Night band (DNB) geolocation error of about 2000 m was corrected. Further, the geolocation biases in the scan profile were also corrected. All these corrections bring the geolocation uncertainties for the J2 L1 products to within 75 m (1-sigma) in both the along-scan and along-track directions.