Frequently Asked Questions

Mapping, Remote Sensing, and Geospatial Data

The USGS provides the mapping and digital geospatial foundation for the Nation.

Filter Total Items: 259
Landsat image of the south end of San Francisco Bay Estuary and associated wetlands
Landsat descending (daytime) acquisitions run from north to south; they cross the equator between 10:00 am and 10:25 am local time on each pass to provide maximum illumination. The exact acquisition start and stop times for each scene are listed in the metadata file that is included in the Landsat Level-1 product, and also displayed on...
Landsat 7 Path 38 Row 31, Acquired March 29, 2013
The Landsat 7 and Landsat 8 satellites orbit the Earth at an altitude of 705 kilometers (438 miles) in a 185-kilometer (115-mile) swath, moving from north to south over the sunlit side of the Earth in a sun synchronous orbit, following the World Reference System (WRS-2). Each satellite makes a complete orbit every 99 minutes, completes about 14...
Earth as Art - Landsat 8
Ascending (nighttime) WRS-2 Path/Row numbers are different from descending (daytime) Path/Rows. Cloud cover values for Landsat night scenes will always be zero. If you know the daytime path/row or coordinates and want to know the nighttime path/row, use the WRS-2 Path/Row to Latitude/Longitude Converter. Use EarthExplorer to search using path/row...
Satellite image showing a picture of northeastern Alaska.
The Landsat Collection 1 Level-1 product identifier includes the Collection processing levels, processing date, collection number, and collection iter category: LXSS_LLLL_PPPRRR_YYYYMMDD_yyyymmdd_CC_TX Where: L = Landsat X = Sensor (“C”=OLI/TIRS combined, “O”=OLI-only, “T”=TIRS-only, “E”=ETM+, “T”=“TM, “M”=MSS) SS = Satellite (”07”=Landsat 7, “08...
Landsat 7 ETM+ Surface Reflectance
Landsat Collection 1 Level-1 data are not corrected for atmospheric conditions, however Landsat Science Products, which include Level-2 Surface Reflectance and Provisional Surface Temperature, and Level-3 Burned Area, Dynamic Surface Water Extent, and Fractional Snow Covered Area are atmospherically corrected. Learn more: Landsat Collections...
Landsat 7 Enhanced Thematic Mapper Plus (ETM+) Level-1 Data
The table below shows the Landsat Collections Level-1 processing levels: Landsat Level-1 Processing Levels Processing Level Description Terrain Precision Correction (L1TP) Radiometrically calibrated and orthorectified using ground control points (GCPs) and digital elevation model (DEM) data to correct for relief displacement.The highest...
Example visualization of U.S. Landsat Analysis Ready Data tile-based structure and time-series stacking.
U.S. Landsat Analysis Ready Data (ARD) are pre-packaged and pre-processed bundles of Landsat data products that make the Landsat archive more accessible and easier to analyze, and reduce the amount of time users spend on data processing for time-series analysis. ARD contains Level-2 products derived from Landsat Collections Level-1 scenes. ARD are...
Landsat 9 logo
Landsat 9 will carry the same instruments that are on the Landsat 8 satellite but with some improvements: Operational Land Imager-2 (OLI-2) for reflective band data. Thermal Infrared Sensor-2 (TIRS-2) for the thermal infrared bands. OLI-2 will have a slightly improved signal-to-noise ratio over Landsat 8's OLI. Landsat 9’s TIRS-2 is a Class...
Rendering of Landsat 9
Landsat 9—a partnership between the USGS and NASA—has a launch readiness date of December 2020. Landsat 9 will be launched from Space Launch Complex 3E at Vandenberg Air Force Base in California and will be delivered into orbit by a United Launch Alliance Atlas V 401 launch vehicle. Learn more: Landsat 9 Mission Since 1972, Landsat satellites...
Scanned USGS historical map of the Yorktown, Virginia area, circa 1907
Many different datums exist, but in the United States only three datums are commonly used: The North American Datum of 1927 (NAD27) uses a starting point at a base station in Meades Ranch, Kansas and the Clarke Ellipsoid to calculate the shape of the Earth.  The North American Datum of 1983 (NAD83) was developed when satellites enabled a better...
Screen shot of National Map Advanced Viewer
USGS online maps (for example, The National Map Viewer) present several background map views. Unlike similar commercial applications, these USGS maps use public domain data. Connecting to services is the preferred method of using these base map displays, but some users want to host their own copies of the underlying data. Following is an...
HI Honolulu US Topo (Browse Image for Story Map)
The field entitled "Topo Map Name"; indicates the name of a USGS standard topographic map. If the map name is known and entered in this field (data may be entered in other fields also), the query will return the features that are wholly or partially located on the map (and that meet the other query parameters). Note that map names frequently are...