DSCOVR_NISTAR_L1B_FILTERED_3 is the Deep Space Climate Observatory (DSCOVR) National Institute of Standards & Technology Advanced Radiometer (NISTAR) Level 1B Radiance Filtered, Version 3 data product.

NISTAR is a 4-band radiometer onboard the National Oceanic and Atmospheric Administration's (NOAA) DSCOVR spacecraft located at the Earth-Sun Lagrange-1 (L-1) point, from which vantage it continuously measures the reflected and emitted radiances of the sunlit face of the Earth. These measurements provide an accurate energy balance measurement that improves our understanding of the Earth’s radiation budget.

NISTAR employs three electrical substitution radiometers and a photodiode to measure reflected sunlight and infrared emission from the Earth. NISTAR measures the absolute irradiance integrated over the entire sunlit face of Earth in four broadband channels minute-by-minute. NISTAR has a 1º field of view (FOV), one large pixel that encompasses the entire sunlit side of the Earth, and a 7º field of regard.

The four measurement bands and their uses are:

1) Total Radiation – 0.2 µm to 100 µm: total radiant power in the ultraviolet (UV), visible, and infrared wavelengths emerging from Earth.
2) Total Solar Reflected – 0.2 µm to 4 µm: reflected solar radiance in UV, visible, and near-infrared wavelengths from Earth.
3) Near Infrared Solar Reflected – 0.7 µm to 4 µm: reflected near-infrared solar radiation from Earth.
4) Photodiode – 0.2 µm to 1.1 µm: tracks the stability of the filters and to verify co-alignment of NISTAR and Earth Polychromatic Imaging Camera (EPIC).

These Level 1B products are the irradiance values computed from Level 1A data collected while the instrument was aimed at the Earth. These data products are in HDF5 format.