When I open a Landsat-8 dataset in ENVI 5.2, ENVI reports that the data are in UTM Zone 18N. This is an image of the western coast of Argentina, which is in UTM Zone 18S. This dataset is exactly as it was downloaded from the USGS's Earth Explorer. However, after I calibrate it using Radiometric Calibration, then the header of the output file shows the UTM zone in the "map info" item as 18S, while the "coordinate system string" shows the UTM zone as 18N. What is wrong? Answer: This is a known issue in ENVI 5.2 that was resolved with the hot fix for ENVI 5.2. You can access this patch by logging into the Exelis website and going to My Account->Downloads. The USGS states that setting the hemisphere to North is intentional: "[The large negative false easing values in S hemisphere Landsat data downloaded from the USGS] are used to eliminate the need for negative values, making it easy for moving between hemispheres."