The NPP/VIIRS Moderate-Resolution Dual Gain Bands Calibrated Radiance 6-Min L1B Swath 750m Near Real Time (NRT) product, short-name VNP02GDC, contains unaggregated, calibrated TOA radiances for those VIIRS sub-pixel samples that are aggregated along-scan during post-calibration ground processing. In other words, this file contains the calibrated M1- M5, M7 and M13 dual gain band data from the nadir and near-nadir zones that would otherwise be discarded following post-calibration aggregation/Earth View Radiometric Calibration Unit.

The VIIRS Level-1 and Level-2 swath products are generated from the processing of 6 minutes of VIIRS data acquired during the NPP satellite overpass. The VIIRS sensor has 5 high-resolution imagery channels (I-bands) that have 32 detectors (32 rows of pixels per scan), with twice the resolution of the M-bands and the DNB, that span the wavelengths from 0.640 micron to 11.45 micron. There are also 7 dual-gain VIIRS bands. The dual gain moderate resolution bands (M1 to M5, M7 and M13) have 6304 samples and the other moderate resolution bands have 3200.

For additional information, see the Algorithm Theoretical Basis Document (ATBD) for the L1B product (https://ladsweb.modaps.eosdis.nasa.gov/missions-and-measurements/viirs/NASARevisedJPSSVIIRSRadCalATBD2014.pdf). The document describes how VIIRS operates in space and provides the equations implemented by the L1B software to generate the MODIS Level-1 intermediate products. It is a summary document the presents the formulae and error budges used to transform VIIRS digital counts to radiance and reflectance.