A chart is used for coordinate clues for Treasure Trails. It is used along with a watch and sextant if one wishes to find a coordinate clue. A chart can be obtained from the Observatory professor at the Observatory. It is not necessary to have a sextant and a watch to obtain the chart. The drop trick can be used to obtain multiple charts if desired.
Due to a game update in the summer of 2014, this item is no longer necessary to solving a coordinate clue. Only the clue and a spade are needed.