# NIST Advanced Radiometer (NISTAR)
*sensor . products*

Three-cavity broadband radiometer on DSCOVR measuring reflected and emitted radiation from the full sunlit Earth disk.

## Specifications
- **product status**: operational
- **deployment context**: orbital
- **manufacturer**: nasa
- **sensor**: {"instrument_family":"passive-optical","measurement_principle":"passive","spectral_range_nm":{"min":200,"max":100000},"spectral_band_count":4,"spec_disclosure":"disclosed"}
- **entity type**: sensor
- **last verified date**: 2026-06-16
- **verified by**: agency-doc
- **claim status**: agency-sourced
- **provider**: nasa
- **attributes**: {"kind":"sensor","product_status":"operational","deployment_context":"orbital","manufacturer":"nasa","description":"Three-cavity broadband radiometer on DSCOVR measuring reflected and emitted radiation from the full sunlit Earth disk.","sensor":"{\"instrument_family\":\"passive-optical\",\"measurement_principle\":\"passive\",\"spectral_range_nm\":{\"min\":200,\"max\":100000},\"spectral_band_count\":4,\"spec_disclosure\":\"disclosed\"}"}
- **relevance**: in-scope

## Editorial
NISTAR is the NIST Advanced Radiometer on DSCOVR, measuring absolute irradiance from the full sunlit Earth disk from the Sun-Earth L1 vantage point.[^nasa-gsfc-nistar] It uses three electrical-substitution radiometers and one photodiode channel to monitor reflected and emitted radiation minute by minute.[^nasa-gsfc-nistar] The four broadband channels are total radiation from 0.2-100 micrometres, reflected solar radiation from 0.2-4 micrometres, near-infrared reflected solar radiation from 0.7-4 micrometres, and a 0.2-1.1 micrometre photodiode channel for filter-stability and EPIC co-alignment checks.[^nasa-gsfc-nistar] The instrument has a one-degree field of view, a seven-degree field of regard, and alignment with the EPIC boresight to within 0.1 degrees.[^nasa-gsfc-nistar] The science accuracy goal is total outgoing Earth radiation from 0.2 to 100 micrometres with accuracy of 1.5 percent or better.[^nasa-gsfc-nistar] NISTAR demonstrates broadband radiometry for daytime Earth-radiation-budget analysis, full-disk reflected and emitted radiation monitoring, and climate energy-balance studies.[^nasa-gsfc-nistar][^wmo-nistar]

## Compositional position
- dscovr (missions) --[mission_payloads]--> NIST Advanced Radiometer (NISTAR)

## Sources
- [nasa-gsfc-nistar] | NASA GSFC DSCOVR EPIC: About NISTAR | https://epic.gsfc.nasa.gov/about/nistar | tier=agency-doc | accessed=2026-06-16
- [wmo-nistar] | WMO OSCAR instrument record: NISTAR | https://space.oscar.wmo.int/instruments/view/nistar | tier=agency-doc | accessed=2026-06-16
- [noaa-nistar-info] | NOAA DSCOVR NISTAR instrument information sheet | https://nesdis-prod.s3.amazonaws.com/migrated/dscovr_nistar_instrument_info_sheet.pdf | tier=agency-doc | accessed=2026-06-16

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Source: https://eo-atlas.org/products/sensor/nistar
Maintainer: SpectraWorks B.V. (CC-BY 4.0)