From: Jeff Behr Date: 3 Apr 1998 11:25:49 Subject: [SCIGN-0381] USGS Analysis Subject ****************************************************************************** SCIGN Electronic Mail Fri Apr 3 11:25:49 PST 1998 Message Number 0381 ****************************************************************************** Author: Jeff Behr Subject: USGS Analysis Subject: USGS Processing on the Web April 3, 1998 The USGS-Pasadena announces daily updates of station positions for 47 SCIGN stations processed to support the SCIGN earthquake response capability. USGS processing uses the GAMIT/GLOBK soft- ware and the IGS predicted ephemeris for rapid update of station positions. Processing typically completes by 1:30 PM PT (21:30 UTC) with graphics of station position posted to the USGS Web pages at: http://www-socal.wr.usgs.gov/scign/Analysis Daily analyses from June 1997 to March 1998 produced coordinate estimates dominated by inaccuracies in the predicted orbits. Day- to-day scatter in station positions were on the order of 26-34 mm horizontal, 32-38 mm vertical. Introduction of the GLOBK module GLORG to redefine the reference frame (ITRF 96) on the basis of well-known SCIGN station coordinates and velocities minimized the region-wide error, leading to typical day-to-day scatter of approx- imately 3-6 mm horizontal, 8-18 mm vertical. We'd like to thank Tom Herring, Bob King and Simon McClusky for their support of the USGS processing. We'd also like to thank the IGS analysis centers for providing predicted orbits for such applications. We welcome comments on our analysis technique, our results and our presentation. Please send them to behr@gps.caltech.edu. Thanks, Jeff Behr ******************************************************************* Jeff Behr SCIGN Operations Center TEL: (626) 583-7816 US Geological Survey FAX: (626) 583-7827 525 S. Wilson Ave. Pasadena, CA 91106 behr@gps.caltech.edu ******************************************************************* [Mailed From: Jeff Behr ]