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Geologic Investigations Series Map I-2786

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### Prepared for The National Aeronautics and Space Administration

# Topographic Map of the Southeast Loire Valles Region of Mars MTM 500k -20/347E OMKT

#### By U.S. Geological Survey

| Summary
This map, compiled photogrammetrically from Viking Orbiter stereo image pairs, is part of a seriesof topographic maps of areas of special scientific interest on Mars.MTM 500k –20/347E OMKT: Abbreviation for Mars Transverse Mercator; 1:500,000 series;center of sheet latitude 20° S., longitude 347.5° E. in planetocentric coordinate system(this corresponds to –20/012; latitude 20° S., longitude 12.5° W. in planetographic coordinatesystem); orthophotomosaic (OM) with color coded (K) topographic contours andnomenclature (T) [Greeley and Batson, 1990]. 

The figure of Mars used for the computation of the map projection is an oblate spheroid (flattening          of 1/176.875) with an equatorial radius of 3396.0 km and a polar radius of 3376.8 km (Kirk and          others, 2000). The datum (the 0–km contour line) for elevations is defined as the equipotential surface          (gravitational plus rotational) whose average value at the equator is equal to the mean radius          as determined by Mars Orbiter Laser Altimeter (Smith and others, 2001).

The image base for this map employs Viking Orbiter images from orbit 651. An orthophotomosaic          was created on the digital photogrammetric workstation using the DTM compiled from stereo          models. Integrated Software for Imagers and Spectrometers (ISIS) (Torson and Becker, 1997) provided        the software to project the orthophotomosaic into the Transverse Mercator Projection.           | First posted April 4, 2004
-  **Map** PDF (23.7 MB) 
-  **Map** EPS (90.7 MB)    This map measures approximately 28 x 40 inches and is best reproduced on a large-format plotter at 600 dpi or greater. 

For questions about the content of this report, contact Mark Rosiek

**For additional information, contact:**Astrogeology Science CenterU.S. Geological Survey2255 N. Gemini DriveFlagstaff, AZ 86001http://astrogeology.usgs.gov/

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### Suggested citation:

Geological Survey, (U.S.), 2003, Topographic map of the Southeast Loire Valles region of Mars MTM 500k -20/347E OMKT: U.S. Geological Survey Geologic Investigations Series Map I-2786, 1 plate, *https://pubs.usgs.gov/imap/2786/*.

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U.S. Department of the Interior |            U.S. Geological Survey           	URL: *http://pubsdata.usgs.gov/pubs/imap/2786/index.html*            Page Contact Information: GS Pubs Web Contact           	Page Last Modified: Wednesday, 30-Nov-2016 17:41:10 EST