# ASTER L2 Surface Reflectance (AST_07XT)
*data products*

## Specifications
- **level**: L2
- **distributor**: usgs
- **spectral range nm**: {"min":520,"max":2430}
- **spectral band count**: 9
- **gsd m**: {"native":30}
- **file format**: Cloud Optimized GeoTIFF
- **access endpoint**: https://search.earthdata.nasa.gov
- **access model**: open
- **licence**: NASA EOSDIS open data (no restrictions on use or redistribution)
- **primary data portal url**: https://www.earthdata.nasa.gov/data/catalog/lpcloud-ast-07xt-004
- **use cases**: ["Lithological mapping using SWIR alteration-mineral absorption features (pre-2008 archive)","Hydrothermal alteration mapping for porphyry copper and epithermal gold exploration","Clay mineral, carbonate, sulphate, and phyllosilicate discrimination using SWIR bands 4-9","Regional geologic mapping combining VNIR structural context with SWIR alteration signatures","Baseline global mineral alteration inventory (most-cited spaceborne SWIR mineral-mapping dataset)","Ongoing VNIR structural and vegetation-contrast mapping (Bands 1-3N operational)","Combined VNIR and TIR emissivity analysis for silicate rock-type discrimination"]
- **practical limitations**: ["SWIR bands 4-9 (1.60-2.43 um) have produced no usable data since approximately April 2008 when anomalous saturation and striping began; detector fully failed January 12, 2009. All SWIR mineral-mapping work draws on the 2000-2008 archive only.","On-demand processing model: scenes must be individually ordered through NASA Earthdata Search; no bulk download of pre-processed tiles.","NASA Earthdata account registration required for all access","60 km swath width gives lower revisit density than wide-swath sensors; global coverage is available but individual target revisits may be limited in the archive","GSD varies by subsystem: VNIR at 15 m, SWIR at 30 m, TIR (separate product) at 90 m. Multi-subsystem analysis requires resampling.","Crosstalk scattering in SWIR data is corrected by the XT product (AST_07XT); do not use uncorrected AST_07 for quantitative mineral mapping."]
- **known artefacts**: ["SWIR data acquired April 2008 to January 11, 2009 exhibit anomalous saturation and striping; treat as unusable for quantitative reflectance analysis","V003 (HDF-EOS2 format) was decommissioned December 15, 2025; V004 (COG format, MERRA-2 atmospheric model) is the current and only active version","Band 3B (backward-looking, 0.78-0.86 um) enables along-track stereo DEM generation but is not a surface-reflectance band; it is a radiance product used for terrain correction"]
- **last verified date**: "2026-05-19T00:00:00.000Z"
- **verified by**: agency-doc
- **claim status**: agency-verified
- **deployment context**: orbital

## Compositional position
- minerals (topics) --[topic_capabilities]--> ASTER L2 Surface Reflectance (AST_07XT)

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Source: https://eo-atlas.org/data_products/aster-l2-surface-reflectance
Maintainer: SpectraWorks B.V. (CC-BY 4.0)