[GRASSLIST:7929] Problem using r.in.gdal to import geoTIFF of US NDVI

[Kenneth Waight]

I'm using r.in.gdal to import a geoTIFF file of U.S. NDVI data.  The  
import is performed, but this message is displayed and the data  
doesn't seem to be projected correctly:

GRASS_INFO_WARNING(20541,1): Datum  
'Not_specified_based_on_Authalic_Sphere' not recognised by GRASS and  
no parameters found. Datum transformation will not be possible using  
this projection information.
Over-riding projection check.
Proceeding with import...

CREATING SUPPORT FILES FOR ndvi.2004113.test
SETTING GREY COLOR TABLE FOR ndvi.2004113.test (8bit, full range)


It's close but is a few km off when I reproject to a lat-lon grid.   
Here's the dataset information:

http://glcf.umiacs.umd.edu/data/modis/ndvi/guide.shtml
U.S.16 day Vegetation Index User Guide

* Projection: Alber's Equal Area Conic Conformal
reprojected from native MODIS projection: Sinusoidal
Central Meridian used was 96d W
std Parallels of 29d 30' 0" and 45d 30' 0"
Latitude of Origin is 0d 0' 0"
Easting & Northing are 0.0000000000 m
Datum: sphere (a sphere of radius 6370997 m)
Resolution is 250 meters
***NOTE*** - When you load the geotiff, many programs may not  
correctly recognize the datum and report a wrong datum (i.e., WGS  
1984). THE DATUM IS THE SPHERE USED IN MODIS DATA, WITH A RADIUS OF  
6370997 METERS!!!


Any ideas?

Ken