INTRODUCING VERSION 2.9 of HTDP
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NOAA's National Geodetic Survey recently released version 2.9 of the HTDP (Horizontal Time-Dependent Positioning) software for transforming positional coordinates and/or geodetic observations across time and between spatial reference frames.  Users may also apply HTDP to predict the velocities and displacements associated with crustal motion in any of several popular reference frames.  
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Version 2.9 expands the list of permissible reference frames to include ITRF2005 and IGS05. The International Earth Rotation and Reference System Service (IERS) released ITRF2005 in September 2006, and the International Global Navigation Satellite System Service (IGS) released IGS05 shortly thereafter.
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Version 2.9 also introduces dislocation models for two recent earthquakes: (1) the magnitude 6.5 San Simeon, CA earthquake that occurred in December 2003, and (2) the magnitude 6.0 Parkfield, CA earthquake that occurred in October 2004.   Both dislocation models were developed by Ingrid Johanson and her colleagues at the University of California at Berkeley.  Chris Pearson of the National Geodetic Survey converted these models into the format used by the HTDP software.  Mike Potterfield of Geodetic Solutions provided critical data for developing the model for the San Simeon earthquake.  For creating the NAD_83 (NSRS 2007) reference frame, Dale Pursell of the National Geodetic Survey applied a prerelease copy of HTDP (Version 2.9) to update relevant GPS observations performed in California from their respective dates of observation to the values that would have been observed on January 1, 2007.
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Users may execute HTDP (Version 2.9) interactively at
	http://www.ngs.noaa.gov
by clicking their mouse on <a href="/TOOLS/">geodetic tool kit</a> and then on <a href="/TOOLS/Htdp/Htdp.shtml">HTDP</a>.  Users may also download the HTDP software and related information from this web site.