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>From: Unidata User Support <address@hidden> >Organization: Unidata Program Center >Keywords: McIDAS ADDE GINI Barb, I got to the bottom of my problem with the Puerto Rico and Hawaiian GINI sectors in NOAAPORT. The problem basically boiled down to the explanation for the "Latin" parameter in the GINI header. The Interface Control Document (ICD) for AWIPS-National... describes this as: Octet Scaling Contents ------+----------------+----------------------------------------------- 39-41 Integer x 10000 Latin - The latitude(s) at which the Mercator projection cylinder intersects the earth 42 Integer Image Resolution - See Table 4.9 - 4.12 The way this is worded made me think that the Mercator projection was a secant one (i.e., the projection cylinder was smaller than the earth and interesected it at +Latin N and -Latin S). Latin is really the latitude at which the image resolution is that described in octet 42. If I set the latitude at which the projection cylinder is tangent to the earth at 0 (zero, the equator), then I can correctly navigate the images in McIDAS. So, it seems to me that the documentation for Latin is incorrect and should be changed (I don't know if you have anything to do with this, but...). The reason that this may not have come up as an issue before is: AWIPS doesn't even read these header values; and GEMPAK only uses the LAT,LON of the "first gridpoint" and "last gridpoint" to do its navigation (i.e., it assumes that it is a tangent Mercator projection). Tom Yoksas