
\subsection{Changes from version 06 (7 September 2004) to version 07 (24 November 2004)}

\begin{itemize}
\item Reworked discussion about lookup tables for \code{psTime}.
\item Moved discussion of lookup tables for $\Delta$UT, $x_p$ and
  $y_p$ into the SDRS, along with more thorough specification.
\item Added discussion about using errors in calculating statistics.
\item Fixed up LMM to be specific to $\chi^2$ fitting.
\item Generalised entry on Gaussian smoothing.
\item modifications to the document name and PSDC number (and refs).
\end{itemize}

\subsection{Changes from version 07 (24 November 2004) to version 08 (8 January 2005)}

\begin{itemize}
\item Added short section on histograms in the presence of errors.
\item Added short note on inverse spherical transformations.
\item Added section on astronomical object models
\end{itemize}

\subsection{Changes from version 08 (8 January 2005) to version 09 (14 February 2005)}

\begin{itemize}
\item Added section on inverse and combined transformations.
\item Added \code{PS_RESAMPLE_LANCZOS[234]}, dropped
  \code{PS_RESAMPLE_LAGRANGE}.
\item Added section on FITS WCS.
\end{itemize}

\subsection{Changes from version 09 (14 February 2005) to version 10 (19 April 2005)}

\begin{itemize}
\item Changes to the Time section:
\begin{itemize}
\item Renamed TDT to TT
\item Misc. cleanups and clarifications
\item Added references
\item Updated definitions of UTC, UT1, JD, and MJD
\item Verbatim Perl code for YMD$\rightarrow$sec and sec$\rightarrow$YMD conversion
\item Verbatim Fortran code for UT1 interpolation
\end{itemize}

\item section reorganization:
\begin{itemize}
\item renamed Astronomical Image Manipulations to Image Manipulations
\item moved Image Manipulations to own subsection before Astronomy Utilities 
\item promoted all PSLib subsections to sections
\end{itemize}
\item defined earth orientation algorithms
\item provided quaternions for rotations
\item moved some sections to reflect order in SDRS (matrix, fftw)
\end{itemize}

\subsection{Changes from version 10 (19 April 2005) to version 11 (27 April 2005)}

\begin{itemize}
\item fixed some typos in the definition of the rotation from CEO to GCRS (Eqn~\ref{CEOtoGCRS}).
\item added references to the SDRS APIs for the Earth Orientation section
\end{itemize}

\subsection{Changes from version 11 (27 April 2005) to version 12 (11 July 2005)}

\begin{itemize}
\item Removed all references to slalib.
\item Updated section on rotations.
\item Divided the robust statistics into robust and fitted statistics,
modified the algorithm somewhat. 
\item Clarifies the LM minimization coding, added gain-factor test description
\end{itemize}

\subsection{Changes from version 12 (11 July 2005) to present}

\begin{itemize}
\item Added complete derivation of rotated ellipse representations
\end{itemize}
