Status of the National Readjustment
The National Readjustment officially began November 15th 2005. All submitted projects prior to this date have been included into the national readjustment.
The first successful completion through the Helmert Blocking strategy was completed
on December 22, 2005.
Dale, Maralyn and Gloria have completed a free adjustment analysis of 26 out of 52 Helmert Blocks. The complete Helmert blocking solution involved a total of 68336 unique stations incorporating 302171 vectors. The database will be updated to reflect all rejections/corrections noted during this analysis phase.
The California Helmert block is on hold until HTDP can be updated to include a dislocation model of the 12/2003 San Simeon earthquake.
The NAD83(NSRS) readjustment team anticipates completion of the free adjustment analysis phase by the end of August 2006. The constrained adjustment phase will then commence with an attempt to rigidly constrain all national CORS sites observed through the November 15th 2005 cutoff date. The latest realization of the CORS coordinates (2004.0) with an epoch date of 2007.0 will be constrained during the final adjustment and is targeted for completion by February 10th, 2007. A complete report of the NAD83(NSRS) readjustment will be written within the following 6 months.
Eric Duval has created a draft webpage for the national readjustment. We anticipate public access to this site by the end of March.
Mike Potterfield, our current contractor assigned to maintain all software required for Helmert blocking, has corrected all known bugs in NETSTAT (the Helmert block analysis software), has successfully updated ADJUST to correctly compute the NEU standard deviations and to correctly count the number of valid observations for each station in the observational summary. Mike also updated ADJUST to show the project ID for each vector in the residual analysis section. Mike is currently working on writing a new plot residual program to aid in our analysis.
A draft policy statement has been created to clarify NGS’ decision to adopt the NAD83 readjustment datum tag as NAD83(NSRS).