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July 1, 2014 - Ground Control Points to be Updated

In September 2014, the Landsat Project will be updating Ground Control Points (GCPs) for 171 paths/rows for data from all Landsat missions.

text file listing the paths/rows can be downloaded, and details about the changes can be found on the Phase 1 GCP Improvement Summary.

The areas affected include island and coastal locations, where meager coverage existed (lack of reference data in the original triangulation, few GCPs available, etc.), desert regions where shifting dunes caused existing GCPs to become obsolete, and other anomalous locations in which an apparent bias remained.

Because the updated GCPs are more accurate, users should consider re-ordering previously downloaded images. Scenes that once processed to a systematic L1G or L1Gt may now process to a precision L1T product. The offsets are significant for many of the scenes, which may affect time series analysis.

More details about this release can be found in the June 2014 Landsat Update.