Changes Introduced in V3.0

The following describes the most significant changes which occurred in the AST library between versions V2.0 and V3.0:

  1. Many changes have been made in the FitsChanFitsChan class in order to bring the FITS-WCS encoding into line with the current versions of the FITS-WCS papers (see http://www.atnf.csiro.au/people/mcalabre/WCS/):

  2. The SkyFrame class now supports two new coordinate systems “ICRS” and “HELIOECLIPTIC”. The default for the System attribute for SkyFrames has been changed from “FK5” to “ICRS”.

  3. The astRateastRate function has been added which allows an estimate to be made of the rate of change of a MappingMapping output with respect to one of the Mapping inputs.

  4. All attribute names for Frames of any class may now include an optional axis specifier. This includes those attributes which describe a property of the whole FrameFrame. For instance, the DomainDomain attribute may now be specified as “Domain(1)” in addition to the simpler “Domain”. In cases such as this, where the attribute describes a property of the whole Frame, axis specifiers will usually be ignored. The exception is that a CmpFrameCmpFrame will use the presence of an axis specifier to indicate that the attribute name relates to the primary Frame containing the specified axis, rather than to the CmpFrame as a whole.

  5. A new subclass of Mapping, the PolyMap, has been added which performs a general N-dimensional polynomial mapping.

  6. A new subclass of Mapping, the GrismMapGrismMap, has been added which models the spectral dispersion produced by a grating, prism or grism.

  7. A new subclass of Mapping, the ShiftMapShiftMap, has been added which adds constant values onto all coordinates (this is equivalent to a WinMapWinMap with unit scaling on all axes).

  8. Minor bugs have been fixed within the PlotPlot class to do with the choice and placement of numerical axis labels.

  9. The SphMapSphMap class has a new attribute called PolarLongPolarLong which gives the longitude value to be returned when a Cartesian position corresponding to either the north or south pole is transformed into spherical coordinates.

  10. The WcsMapWcsMap class now assigns a longitude of zero to output celestial coordinates which have a latitude of plus or minus 90 degrees.

  11. The NatLatNatLat and NatLonNatLon attributes of the WcsMap class have been changed so that they now return the fixed native coordinates of the projection reference point, rather than the native coordinates of the user-defined fiducial point.

  12. Notation has been changed in both the WcsMap and FitsChan classes to reflect the convention used in the FITS-WCS papers that index “i” refers to a world coordinate axis, and index “j” refers to a pixel axis.

  13. Changes have been made to several Mapping classes in order to allow the astSimplifyastSimplify function to make simplifications in a CmpMapCmpMap which previously were not possible.

  14. The SlaMapSlaMap class has been extended by the addition of conversions between FK5 and ICRS coordinates, and between FK5 and helio-ecliptic coordinates.

  15. The SpecMapSpecMap class has been changed to use the equation for the refractive index of air as given in the current version of FITS-WCS paper III. Also, the forward and inverse transformations between frequency and air-wavelength have been made more compatible by using an iterative procedure to calculate the inverse.