Frequently Asked Questions

Mapping, Remote Sensing, and Geospatial Data

The USGS provides the mapping and digital geospatial foundation for the Nation.

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Geometric Desert - Earth As Art image of Egypt
Definitive Ephemeris is used for geometrically correcting Landsat 7 data and providing improved accuracy over predicted ephemeris. Learn more (and download DE files): Landsat Definitive Ephemeris
Aug 2013 Response Linearization Look Up Tables Update Close up - Band 6
Landsat Response Linearization Look Up Tables (RLUT) are additional files that accompany Calibration Parameter Files (CPFs) and contain a mapping lookup table to linearize the output of the Landsat 8 Operational Land Imager (OLI) detectors. Learn more (and download RLUT files): Landsat Response Linearization Look Up Tables
White Sands Radiometric Calibration Site
Landsat Bias Parameter Files (BPFs) supply radiometric correction parameters that are applied during Level-1 processing of Landsat data. Learn more (and search for BPF files): Landsat Bias Parameter 
Calibration/Validation Test Sites
Landsat Calibration Parameter Files (CPFs) provide radiometric and geometric coefficients needed for processing of raw, uncorrected Landsat image data into Level-1 data products. Over 15,000 coefficients are issued to span distinct timeframes and are updated with improved calibration coefficients. CPFs are often updated with improved coefficients...
Landsat 8 Collection 1 Quality Assessment Example
The C Function of Mask (CFMask) algorithm populates cloud, cloud confidence, cloud shadow, and snow/ice pixels in the processing of Landsat Collections Level-1 data products, with the results represented as bit-mapped values within the Landsat Collection 1 Level-1 Quality Assessment (QA) Band.  CFMask derives from the Function of Mask (FMask), an...
Landsat 7 100,000th orbit image
The Landsat Collection 1 Level-1 product metadata (MTL.txt) file includes a SATURATION_BAND_ x”parameter for each Landsat band. This field indicates the presence of radiometric saturation for each bandin every Landsat scene. Learn more: Landsat Collections Level-1 Saturation Bits Parameter 
Zenith and Azimuth Angles Associated with Solar Angle Bands
The Landsat Collection 1 Angle Coefficient file provides sensor viewing angle model coefficients that can be used to create angle bands, and allows users to compute the solar and sensor viewing angles on a per-pixel basis. Learn more: Solar Illumination and Sensor Viewing Angle Coefficient Files 
Crop of Landsat 7 Path 38 Row 31, Acquired March 29, 2013
The Landsat 7 SLC-off artifact does not change how the data are placed into Landsat Collection tiers, as tier classifications are determined by the radiometric and geometric accuracy of each scene. Learn more: Landsat Collections Landsat Data Access
Lenticular clouds over hills in New Zealand.
Landsat Level-1 data can be rescaled to the top of atmosphere (TOA) reflectance and/or radiance using radiometric rescaling coefficients provided in the metadata file (MTL.txt) that is delivered with the Landsat Level-1 product. The MTL file also contains the thermal constants needed to convert thermal band data to TOA brightness temperature (BT...
Earth As Art image of Kazakhstan
The historical Landsat Level-1 Scene ID is in the EarthExplorer metadata. After entering a search using the historical Scene ID, the Landsat Level-1 Collection 1 Product Identifier will be returned in the search results. The results can be exported from EarthExplorer in a variety of formats for metadata parsing. We also encourage use of the Bulk...
Earth As Art image Terkezi Oasis
The USGS archive contains data acquired by the Landsat satellites from 1972 to present. Data is downlinked to various ground stations around the world. While each ground station in the International Cooperator (IC) network is the primary source for distributing the captured data in their area, copies of the data have also been made available to...
Landsat image of the south end of San Francisco Bay Estuary and associated wetlands
Landsat descending (daytime) acquisitions run from north to south; they cross the equator between 10:00 am and 10:25 am local time on each pass to provide maximum illumination. The exact acquisition start and stop times for each scene are listed in the metadata file that is included in the Landsat Level-1 product, and also displayed on...