Landsat "Real-Time" (RT) scenes contain valid image file data and are usable as is.
Newly acquired Landsat 7 Enhanced Thematic Mapper Plus (ETM+) and Landsat 8 Operational Land Imager (OLI)/Thermal Infrared Sensor (TIRS) data require a period of evaluation and calibration adjustment after acquisition, but are processed immediately based on preliminary calibration coefficients, assigned to the temporary RT Tier, and made available for download.
When definitive calibration information becomes available, RT scenes are reprocessed and assigned to the appropriate Tier category. The Landsat Product Identifier is changed to reflect the new category.
- Landsat 8 TIRS data are not initially co-registered with OLI to meet specifications. After 14 to 16 days, line-of-sight model parameters are refined based on data acquired during biweekly calibration maneuvers, after which scenes are placed into either Tier 1 or Tier 2. The geometry of the OLI data and the radiometry of OLI and TIRS does not change.
Landsat 7 ETM+ data use predicted ephemeris and initial bumper mode parameters during initial processing into RT. Within about 26 days, the final calibration and bumper mode parameters are applied, and the scene is placed into either Tier 1 or Tier 2.
After the follow-on processing is complete and the data is available as T1 or T2, the RT data is removed.
Visit the Landsat Collections page for complete details.