V2.0

• POLCAL can now produce Stokes vectors from single-beam data.

• SUN/223 has been updated to include discussion of single-beam data.

• POLKA will now allow rotation between images in single-beam mode.

• POLPACK (including POLKA) may now be used from the ICL and IRAF cl command languages.

• POLKA) now has a REFIN parameter which may be used to specify a reference image to which the other images should be aligned. A reference image specified in this way will not be processed to create any output files.

• The NEWCOLMAP parameter has been removed from POLKA. POLKA will now use a private colour map automatically when necessary.

• The Dump and Restore commands in the POLKA File menu now have an option to dump and restore the feature positions, masks and sky areas for the display image alone to a text file.

• A new command called POLSIM has been added, which creates simulated intensity data from a cube of Stokes vectors and a set of template intensity images. This is a useful tool for investigating noise characteristics within a set of intensity images.

• A new command called POLIMAGE has been added which allows a 1 or 2 dimensional image to be created from a column of a catalogue.

• The reference direction for Stokes parameters created by POLCAL, POLBIN and POLVEC has been changed. Prior to V2.0 the reference direction was the WPLATE=0 position ( i.e. the direction of the fixed analyser). As of V2.0, the reference direction will be north if there is WCS information available to define north, or the positive Y axis (i.e. the second pixel axis) otherwise. POLVEC and POLBIN can still read data sets created by earlier versions of POLPACK which use the previous convention, but will write data sets using the new convention.

• The angles produced by POLBIN and POLVEC which give the orientation of the polarization vectors are now referred to the same reference direction as the Stokes parameters. Previously, these angles were measured anti-clockwise form the positive X axis ( i.e. the first pixel axis). They are now measured anti-clockwise from the same reference direction as the Stokes parameters. POLPLOT will automatically determine the correct convention to use, based on the POLPACK version number stored in the supplied catalogue.

• The way in which the reference direction is recorded within a POLPACK data file has been changed. Prior to V2.0, the POLPACK extension item named ANGROT was used. The reference direction is now specified by the POLANAL co-ordinate Frame added to the WCS component when POLIMP or POLEXT is run. V2.0 will read ANGROT values in existing data sets, but will no longer write them.

• The facilities for processing textual values within an import control table used by POLIMP have been expanded. Concatenation and replacement can now be combined together, using parentheses to indicate the order in which sub-expressions should be evaluated. References to keywords may be included in a replacement specification (on either side of the equals sign) by enclosing the name in parentheses. In fact such parentheses may include any general character expression, containing nested replacement specifications, concatentation, etc.

• The choice of default vector scale in POLPLOT has been improved. It now uses the 90% percentile point, so that 10% of all vectors are at least equal to 1/15th of the length of the smaller plot dimension.

• The facilities for accessing groups of data files have been changed to allow multiple NDFs within a single container file to be read.

• A bug has been fixed which limited the number of data files which could be processed by POLIMP when run as a monolith.

• A bug in POLEXT has been fixed which prevented POLEXT from being able to change an IMGID value.

• Specifying the keyword STARTHELP when starting POLKA no longer requires POLKA to use a private colour map.

• A bug in POLKA has been fixed which resulted in a Tcl error being reported when Saving or Exiting if any of the image names begin with an upper case letter.

• POLEXT and POLIMP no longer abort if non-unique IMGID values are supplied. This allows IMGID values to be set for extracted O and E ray images.

• POLEXT now allows POLPACK extension items to be set for Stokes cubes and extracted O or E ray images, as well as raw intensity images. The extension items are now written to output parameters as well as to the screen.