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Question:

Where can I find the solar exoatmospheric spectral irradiances (ESUN) values for Landsat 8 OLI data?

Answer:

ESUN values are not provided for Landsat 8 data because they are not required for converting data to reflectance. Landsat 8’s Operational Land Imager (OLI) adopted two independent National Institute for Standards and Technology (NIST) traceable radiance and reflectance calibration methods. The Landsat 8 metadata file provides coefficients necessary to convert to radiance and reflectance from the quantized and calibrated Digital Numbers (DNs) of the product. Thus, ESUN values are not required for reflectance conversion.

Relative Spectral Response (RSR) of the OLI spectral bands can be used along with the user’s preferred solar spectrum to calculate ESUN values corresponding to Landsat 8 OLI bands. (NOTE: ESUN values calculated from RSRs were not used for OLI calibration).