## Changes Introduced in V4.6

The following describes the most significant changes which have occurred in the AST library between versions V4.5 and V4.6:

1. The TimeFrameTimeFrame class now support Local Time as a time scale. The offset from UTC to Local Time is specified by a new TimeFrame attribute called LTOffsetLTOffset.

2. A new class called Plot3DPlot3D has been added. The Plot3D class allows the creation of 3-dimensional annotated coordinate grids.

3. A correction for diurnal aberration is now included when converting between AZEL and other celestial coordinate systems. The correction is based on the value of the ObsLatObsLat FrameFrame attribute (the geodetic latitude of the observer).

4. A bug has been fixed which caused the DUT1 attribute to be ignored by the SkyFrameSkyFrame class when finding conversions between AZEL and other celestial coordinate systems.