105°W

104°W

103°W

102°W

101°W

100° W

105°W

104°W

103°W

102°W

101°W

100°W

17°

16°

14°

15°

13°

13°

14°

15°

16°

17°

MC–17

MC–2

MC–3

MC–4

MC–8 MC–9 MC–10 MC–11

MC–1

MC–16 MC–18 MC–19

MC–24

MC–25

MC–26

MC–30

120°

120° 60°

60°

0°

30°

65°

180° 135° 90° 45° 0°

–30°

–65°

0°

30°

65°

–30°

–65°

255°E

17.5°

256°E

257°E

258°E

259°E

260° E

255°E

256°E

257°E

258°E

259°E

260°E

17.5°

17°

16°

14°

15°

13°

12.5°

13°

14°

15°

16°

17°

6000

8000

9000

11,000

12,000

7000

14,000

16,000

4000

3000

4000

3000

5000

4000

ASCRAEUS MONS

10 20 30 40 50 60 80 90 70 100 

SCALE 1:502 000 (1 mm = 502 m) AT 250° E (110° W) LONGITUDE

TRANSVERSE MERCATOR PROJECTION

KILOMETERS

CONTOUR INTERVAL 250 METERS

Planetocentric latitude and east longitude coordinate system shown in black.

Planetographic latitude and west longitude coordinate system shown in red.

10

U.S. DEPARTMENT OF THE INTERIOR

U.S. GEOLOGICAL SURVEY

GEOLOGIC INVESTIGATIONS SERIES I–2796

Version 1.0

Prepared for the

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

12.5°

Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Dimensional calibration may vary between electronic plotters and between X and Y 

directions on the same plotter, and paper may change size due to atmospheric conditions; therefore, scale and proportions may not be true on plots of this map.

Digital files available on World Wide Web at http://geopubs.wr.usgs.gov/i-map/i2796

QUADRANGLE LOCATION

Photomosaic showing location of map area. An outline of 

1:5,000,000-scale quadrangles is provided for reference.

18,000 

17,750 

17,500 

17,250 

17,000 

16,750 

16,500 

16,250 

16,000 

15,750 

15,500 

15,250 

15,000 

14,750 

14,500 

14,250 

14,000 

13,750 

13,500 

13,250 

13,000 

12,750 

12,500 

12,250 

12,000 

11,750 

11,500 

11,250 

11,000 

10,750 

10,500 

10,250 

10,000 

9750

9500 

9250 

9000 

8750 

8500 

8250 

8000 

7750 

7500 

7250 

7000 

6750 

6500 

6250 

6000 

5750 

5500 

5250 

5000 

4750 

4500 

4250 

4000 

3750 

3500 

3250 

3000 

2750 

2500 

2250 

2000 

1750 

1500 

1250

NOTES ON BASE Contour Guide, in meters

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 15/257E OMKT: Abbreviation for Mars Transverse Mercator; 1:500,000 series; 

center of sheet latitude 15° N., longitude 257.5° E. in planetocentric coordinate system (this corresponds to 15/102; latitude 15° N., longitude 102.5° W. in planetographic coordinate system); orthophotomosaic (OM) with color-coded (K) 

topographic contours and nomenclature (T) [Greeley and Batson, 1990]

ADOPTED FIGURE

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 (MOLA; Smith and others, 

2001).

PROJECTION

The projection is part of a Mars Transverse Mercator (MTM) system with 20° wide zones. For 

the area covered by this map sheet the central meridian is at 250° E. (110° W.). The scale factor at the central meridian of the zone containing this quadrangle is 0.9960 relative to a nominal scale of 1:500,000.

COORDINATE SYSTEM

Longitude increases to the east and latitude is planetocentric as allowed by IAU/IAG standards 

(Seidelmann and others, 2002) and in accordance with current NASA and USGS standards 

(Duxbury and others, 2002). A secondary grid (printed in red) has been added to the map as a 

reference to the west longitude/planetographic latitude system that is also allowed by 

IAU/IAG standards (Seidelmann and others, 2002) and has been used for previous Mars maps.

CONTROL

Horizontal and vertical control was established using the Mosaicked Digital Image Model 2.0 

(MDIM 2.0; Kirk and others, 2000) and MOLA data. A portion of MDIM 2.0 covering the 

mapping area was extracted in simple cylindrical projection. This MDIM image was georeferenced to the MOLA data with an affine transformation. The MDIM image and georeferencing 

information were imported into a digital photogrammetric workstation (Miller and Walker, 

1993) and used as an orthophoto to provide horizontal control to stereopairs of Viking 

imagery. The horizontal information was used to extract vertical control from the MOLA data. 

Note that the distribution of Viking Orbiter images suitable for mapping at a scale of 

1:500,000 is uneven. Areas mapped in this series are chosen, often in blocks of two or more 

adjacent quadrangles, based on scientific interest as well as on the availability of suitable data 

for accurate mapping.

CONTOURS

Contours were derived from a digital terrain model (DTM) compiled on a digital photogrammetric workstation using Viking Orbiter stereo image pairs with orientation parameters 

derived from an analytic aerotriangulation. Contours were drawn automatically using a commercial geographic information system (GIS) software package (Environmental Systems 

Research Institute, 1994). For the stereomodels, the local expected vertical precision, based on 

image resolutions, parallax-to-height ratio (that is, convergence angle), and a matching accuracy of 0.2 pixel ranges from 32 m to 80 m, with a mean of 47 m. Elevation (in meters) is 

given with respect to the adopted Mars topographic datum (see "Adopted Figure" section). A 

comparison of the DTM values at the MOLA point locations shows that the DTM is on average 0.5 m lower than the MOLA points (n=249,313; μ=-0.5 m; σ=21 m). Contour lines were 

generated automatically using GIS software and were not edited. Because the contour lines 

were not edited, small closed contour lines, contour lines that intersect, and contour lines that 

do not match features are present. The post spacing for the DTM is 600 m; features that are 

less than 600 m in size will not be resolved and features that are smaller than 1800 m in size 

may only have four elevation measurements associated with them. This lack of elevation 

measurements may result in contour lines that do not adequately represent some features. The 

purpose of this mapping project is to produce the digital orthophoto and DTM. This map provides a graphical representation of the digital products that are available.

IMAGE BASE

The image base for this map employs Viking Orbiter images from orbits 090, 055, 892, and 

643. 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.

REFERENCES

Duxbury, T.C., Kirk, R.L., Archinal, B.A., and Neumann, G.A., 2002, Mars Geodesy/Cartography Working Group Recommendations on Mars Cartographic Constants and Coordinate Systems, in Joint International Symposium on Geospatial Theory, Processing and 

Applications, Ottawa, Canada, 2002, Commission IV, Working Group 9—Extraterrestrial 

Mapping, Proceedings: Ottawa, Canada, International Society for Photogrammetry and 

Remote Sensing [http://www.isprs.org/commission4/proceedings/paper.html].

Environmental Systems Research Institute, 1994, Arc commands: Redlands, Calif., Environmental Systems Research Institute, Inc.

Greeley, Ronald, and Batson, R.M., 1990, Planetary mapping: New York, Cambridge University Press, p. 261–276.

Kirk, R.L., Lee, E.M., Sucharski, R.M., Richie, J., Grecu, A., and Castro, S.K., 2000, MDIM 

2.0—A revised global digital image mosaic of Mars, in Lunar and Planetary Science 

XXXI: Houston, Lunar and Planetary Institute, abstract 2011 [CD–ROM].

Miller, S.B., and Walker, A.S., 1993, Further developments of Leica Digital Photogrammetric 

Systems by Helava, ACSM/ASPRS Annual Convention and Exposition, Technical 

Papers, v. 3, p. 256–263.

Seidelmann, P.K. (chair), Abalakin, V.K., Bursa, M., Davies, M.E., De Bergh, C., Lieske, 

J.H., Oberst, J., Simon, J.L., Standish, E.M., Stooke, P., and Thomas, P.C., 2002, Report 

of the IAU/IAG Working Group on Cartographic Coordinates and Rotational Elements of 

the Planets and Satellites: 2000: Celestial Mechanics and Dynamical Astronomy, v. 82, p. 

83–110.

Smith, D.E., Zuber, M.T., Frey, H.V., Garvin, J.B., Head, J.W., Muhleman, D.O., Pettengill, 

G.H., Phillips, R.J., Solomon, S.C., Zwally, H.J., Banerdt, W.B., Duxbury, T.C., Golombek, M.P., Lemoine, F.G., Neumann, G.A., Rowlands, D.D., Aharonson, O., Ford, P.G., 

Ivanov, A.B., McGovern, P.J., Abshire, J.B., Afzal, R.S., and Sun, X., 2001, Mars 

Orbiter Laser Altimeter (MOLA)—Experiment summary after the first year of global 

mapping of Mars: Journal of Geophysical Research, v. 106, p. 23,689–23,722.

Torson, J.M., and Becker, K.J., 1997, ISIS—A software architecture for processing planetary 

images (abs.), in Lunar and Planetary Science Conference XXVIII: Houston, Lunar and 

Planetary Institute, p. 1443.

Prepared on behalf of the Planetary Geology and Geophysics Program, Solar System Exploration Division, Office of Space Science, 

National Aeronautics and Space Administration.

Manuscript approved for publication June 23, 2003

NORTH

WEST

SOUTH

EAST

12

15

14

11

9

8

3

2

5

6

13

1

16

17

10

7

4

The following is a list of image pairs used to produce the 

topographic information for this map. Numbers below correspond to the numbers on the diagram above. Shaded area 

indicates MOLA data.

 ID IMAGE PAIR ID IMAGE PAIR

 1 090A52/055A27 10 892A10/643A75

 2 090A53/055A27 11 892A11/643A75

 3 090A54/055A27 12 892A12/643A75

 4 090A55/055A27 13 892A13/643A75

 5 090A55/055A29 14 892A13/643A77

 6 090A56/055A27 15 892A14/643A75

 7 090A56/055A29 16 892A14/643A77

 8 090A57/055A29 17 892A15/643A77

 9 090A58/055A29

MTM 15/257E QUADRANGLE VIKING STEREOMODEL COVERAGE

Topographic Map of the Northeast Ascraeus Mons Region of Mars

MTM 500k 15/257E OMKT

By

U.S. Geological Survey

2004