Landsat 7 and Landsat 8 Level-1 Real-Time scenes are available for download within 4-6 hours after acquisition. For Landsat 7 Level-1 scenes, the timeframe from acquisition (Real-Time) to Tier 1 or Tier 2 takes approximately 24-26 days to allow for application of the refined bumper mode parameters to the Real-Time scene. For Landsat 8 Level-1 scenes it takes approximately 14-16 days to process to a Tier 1 or Tier 2 product while refined Thermal Infrared Sensor (TIRS) instrument line of sight model parameters are applied to the Real-Time scene. Visit the Collection 1 Tiers section on this page for more information about the Landsat Collections Tier structure: https://www.usgs.gov/land-resources/nli/landsat/landsat-collection-1. Collection 2 Level-2 Surface Reflectance and Surface Temperature products are typically available within 24 hours after a scene has been processed into Tier 1 or Tier 2. Landsat 7 and Landsat 8 both utilize NASA's Goddard Earth Observing System Model Version 5 Forward Processing for Instrument Teams (GEOS-5 FP-IT) Atmospheric Assimilation Products for Level-2 product generation.Upon launch and on-orbit checkout, Landsat 9 will deliver Collection 2 Level-1 Tier 1 or Tier 2 scenes within 4-6 hours of acquisition, and a Level-2 Surface Reflectance and Surface Temperature product within 3 days. Landsat 9 will also utilize the GEOS-5 FP-IT atmospheric auxiliary data product for Level-2 product generation. </section>
