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Changes Introduced in V4.1

The following describes the most significant changes which occurred in the AST library between versions V4.0 and V4.1:

  1. A new control flag has been added to the AST_RESAMPLE<X>/astResample<X> functions which produces approximate flux conservation.

  2. New constants AST__SOMB and AST__SOMBCOS have been added to AST_PAR. These specify kernels for AST_RESAMPLE and AST_REBIN based on the ``Sombrero'' function ( $2*J1(x)/x$ where $J1(x)$ is the first order Bessel function of the first kind).

  3. The SkyFrame class now supports a System value of AZEL corresponding to horizon (azimuth/elevation) coordinates.

  4. The FitsChan class allows the non-standard strings ``AZ-'' and ``EL-'' to be used as axis types in FITS-WCS CTYPE keyword values.

  5. The Frame class now has attributes ObsLon and ObsLat to specify the geodetic longitude and latitude of the observer.

  6. The ClockLon and ClockLat attributes have been removed from the TimeFrame class. Likewise, the GeoLon and GeoLat attributes have been removed from the SpecFrame class. Both classes now use the ObsLon and ObsLat attributes of the parent Frame class instead. However, the old attribute names can be used as synonyms for ObsLat and ObsLon. Also, dumps created using the old scheme can be read succesfully by AST V4.1 and converted to the new form.

  7. A new routine AST_MAPSPLIT has been added to the Mapping class. This splits a Mapping into two component Mappings which, when combined in parallel, are equivalent to the original Mapping.

  8. The default value for the SkyRefIs attribute has been changed from ``Origin'' to ``Ignored''. This means that if you want to use a SkyFrame to represent offsets from some origin position, you must now set the SkyRefIs attribute explicitly to either ``Pole'' or ``Origin'', in addition to assigning the required origin position to the SkyRef attribute.



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Next: Changes Introduced in V4.2
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AST A Library for Handling World Coordinate Systems in Astronomy
Starlink User Note 210
R.F. Warren-Smith & D.S. Berry
24th May 2011
E-mail:ussc@star.rl.ac.uk

Copyright (C) 2009 Science \& Technology Facilities Council