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| USGS › Geography › Earth Resources Observation and Science (EROS) Center |
Landsat ETM+ Image (Seattle, WA)
Beginning September 30 2008, the USGS will offer all users the Landsat 7 archive data at no charge using a standard data product recipe. The Landsat TM and Landsat MSS archive will also become available at no charge with a standard recipe in December 2008.
Please view the Landsat Web site for additional information.
The Landsat Enhanced Thematic Mapper Plus (ETM+) is a sensor carried onboard the Landsat 7 satellite and has acquired images of the Earth nearly continuously since July 1999, with a 16-day repeat cycle. An instrument malfunction occurred on May 31, 2003; as a result, all Landsat 7 image data acquired from July 14, 2003 (20:32:40 GMT) to the present were collected in SLC-off mode. Image data acquired from 5/31/03 (21:42:35 GMT) to 7/14/03 (20:32:40 GMT) and from 9/3/03 (01:32:15 GMT) to 9/17/03 (06:22:27 GMT) are not available.
On April 1, 2007, the Landsat 7 mission began imaging in an alternate mirror-scanning control mode from the original Scan Angle Monitor (SAM) process that has been used since the satellite was launched in 1999. This change, known as Bumper Mode, is necessary due to a predictable physical wear of the mirror bumpers mounted within the Enhanced Thematic Mapper Plus (ETM+) imaging system. Landsat 7 data users should notice little or no change as a result of this transition. Five years ago, the Landsat 5 Thematic Mapper (TM) scanner was successfully converted to this alternate imaging mode, and customers have reported no problems related to that change.
Landsat ETM+ image data consist of eight spectral bands (band designations), with a spatial resolution of 30 meters for bands 1 to 5 and band 7. Resolution for band 6 (thermal infrared) is 60 meters and resolution for band 8 (panchromatic) is 15 meters. Approximate scene size is 170 km north-south by 183 km east-west (106 mi by 114 mi).
| Product Type | *L1T – Terrain Corrected |
|---|---|
| Pixel Size |
15m – Panchromatic band 8 30m – Reflective bands 1-5 and 7 60m – Thermal bands 6H and 6L |
| Output Format | GeoTIFF |
| Resampling Method | Cubic Convolution (CC) |
| Map Projection |
UTM Polar Stereographic for Rows 102 to 122** |
| Image Orientation | Map (North Up) |
| Distribution | FTP Download Only |
| Delivery Time |
Immediate for FTP Downloads Users will receive an estimated delivery time upon request of an archive scene. |
For all Landsat 7 ETM+ data (including SLC-off products), the following levels of correction are available to the general public. While most data available at no charge will be processed as Level 1T (precision and terrain corrected), certain scenes do not have ground control or elevation data necessary for precision or terrain correction, respectively. In these cases, the best level of correction will be applied (Level 1G-systematic or Level 1Gt-systematic terrain).
*For information on how to fill in the SLC-off gaps using commercial image processing software, please visit:
http://landsat.usgs.gov/tools_faq.php?id=45
All Landsat ETM+ scenes in the USGS archive can be searched by geographic location using the USGS Global Visualization Viewer (GloVis) or the Earth Explorer Web sites. Only scenes with browse capability can be searched on GloVis. All Landsat 7 ETM+ data are referenced to WRS-2, the Worldwide Reference System of paths and rows.
New Landsat ETM+ scenes generally become available for search and download within 6 to 24 hours after data acquisition. To view real-time acquisitions of Landsat over North America, please visit EarthNow!
Some Landsat 7 ETM+ scenes of areas outside the United States are not archived or distributed by USGS EROS. These scenes may be available from International Ground Stations (IGSs). IGS data are not products of USGS EROS and therefore prices, available formats, and processing options may vary according to the data provider. Metadata for most of the IGS-downlinked scenes is searchable through Earth Explorer.
Browse images of available scenes may be viewed by searching on Earth Explorer or GloVis.
Each Landsat ETM+ browse image is a resampled JPEG of the raw scene data. The browse image will be displayed as a 5,4,3 (RGB) composite with a 2% linear color stretch, based on individual scene content.
The image preview for SLC-off data includes an overlay and numerical grid that illustrates the approximate extent of the SLC-off image gaps.
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