The pol2map command used to create I, Q, U maps and vector catalogues from POL2 data now adds a column called “AST” to the output catalogue. This new column holds an integer for each row, indicating if the row is inside (1) or outside (0) the AST mask. It uses the poledit command in the Starlink POLPACK package, as described in an earlier post.
A possible use of this new column would be to select the vectors corresponding to the inside of the AST mask when viewing the vector map in GAIA. To do this, the selection criterion “$ast == 1” should be used within the GAIA polarimetry toolbox.