Dark terrain is generally more heavily cratered than light terrain and much less commonly cut by grooves. The map area is in the sub-Jupiter hemisphere of Ganymede. All images used for mapping were obtained by Voyager 1. The terminator was located at about long 305 when the images were obtained, and all coverage in Jg-2 west of about long 60 was obtained with emission angles too large to produce images usable for mapping. All attributes created during the creation process were verified by displaying the lines in both the database and the spatial coverage, but no formal tests were performed.
Line geometry is topologically clean.
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