[GRASS-user] Datum not recognized by GRASS

[Anders Gonçalves da Silva]

Hello all. I am trying to add a GeoTIFF to a project, but I keep getting the following message:

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GRASS 6.4.0RC6 (pontal):~/Documents/Academic/Thesis/Archive/Sampling > gdalinfo pontal.TIF 
Driver: GTiff/GeoTIFF
Files: pontal.TIF
Size is 4337, 2727
Coordinate System is:
PROJCS["UTM Zone 23S",
   GEOGCS["South_American_1969",
       DATUM["South_American_1969",
           SPHEROID["South American 1969",6378160,298.2500000654724]],
       PRIMEM["Greenwich",0],
       UNIT["degree",0.0174532925199433]],
   PROJECTION["Transverse_Mercator"],
   PARAMETER["latitude_of_origin",0],
   PARAMETER["central_meridian",-45],
   PARAMETER["scale_factor",0.9996],
   PARAMETER["false_easting",500000],
   PARAMETER["false_northing",10000000],
   UNIT["unknown",1]]
Origin = (280686.235600000014529,7573063.005800000391901)
Pixel Size = (30.000000000000000,-30.000000000000000)
Metadata:
 TIFFTAG_SOFTWARE=ERDAS IMAGINE
 AREA_OR_POINT=Area
Image Structure Metadata:
 INTERLEAVE=PIXEL
Corner Coordinates:
Upper Left  (  280686.236, 7573063.006) ( 47d 7'24.05"W, 21d55'58.77"S)
Lower Left  (  280686.236, 7491253.006) ( 47d 8'4.36"W, 22d40'17.64"S)
Upper Right (  410796.236, 7573063.006) ( 45d51'49.82"W, 21d56'39.98"S)
Lower Right (  410796.236, 7491253.006) ( 45d52'6.24"W, 22d41'0.39"S)
Center      (  345741.236, 7532158.006) ( 46d29'51.35"W, 22d18'33.65"S)
Band 1 Block=4337x5 Type=Byte, ColorInterp=Red
Band 2 Block=4337x5 Type=Byte, ColorInterp=Green
Band 3 Block=4337x5 Type=Byte, ColorInterp=Blue

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I have tried to use gdalwarp to reset it to something that GRASS can read. While I get it to run, the projections are not lining up. In particular, it seems to be off by a few degrees to the East. Any help in fixing this would be greatly appreciated. Thank you.

Anders.