From P. Mon Nov 20 08:49:38 1995 From: P. (P.) Date: Mon, 20 Nov 1995 8:49:38 PST Subject: [IGSMAIL-1119] SOPAC Orbits Message-ID: ****************************************************************************** IGS Electronic Mail Mon Nov 20 8:49:38 PST 1995 Message Number 1119 ****************************************************************************** Author: P. Fang, P. Tregoning, and Y. Bock Subject: SOPAC Orbits Scripps Orbit and Permanent Array Center (SOPAC) Date: November 20, 1995 Subject: Update on SOPAC Rapid and Predicted Orbits Service To support a wide range of geophysical and meteorological research activities using GPS technology, including early earthquake response for the southern California continuous GPS array (SCIGN/PGGA), in-the-field processing for the University NAVSTAR Consortium (UNAVCO), and near-real time precipitable water estimation for the U.S. CORS network, we have upgraded our rapid and predicted (extrapolated) orbit service, effective immediately. Note: Final precise orbits are available with a delay of about 7 days with a precision of 8-11 cm. These are contributed to the rapid and final orbit products of the International GPS Service for Geodynamics (IGS). The computation of these orbits is delayed to allow data from sites which may have been slow in being made available to the IGS analysis centers to be included in the solutions. The IGS combined rapid orbits are available from the IGS Global Data Centers within 7-10 days of data collection with a precision approaching 5 cm. Our rapid service provides the following products: 1. Precise orbit determination with 14-18 hours delay from end of IGS data collection epoch (24 h UT), with a precision of 15-20 cm rms. 2..Predicted orbits available at about 1800 UT on the current day for which they are valid, that is 6 hours before IGS daily data collection end, or 6 hours in real time. The precision of these predicted orbits is 40-80 cm RMS. The predicted orbit provides an ephemeris for a particular day up to 20 hours earlier than the first SIO computed precise orbit spanning the same period. We are currently experimenting with an orbit that is fully available in real time. 3. Pole position estimates with 14-18 hours delay as per item 1, with a precision below 0.5 mas for both X and Y components and an offset of 0.1 mas in X and 0.4 mas in Y when compared with IERS Bulletin A. The above products are available on our anonymous ftp server (see below) under: Items 1 and 2: combination/wwww Item 3 : products/wwww Final Orbits : products/wwww where wwww is the GPS week number. All orbit products are available in NGS SP3 format and pole position estimates are in free format. The file naming convention is as follows: sipwwwwd.sp3 - predicted orbit sirwwwwd.sp3 - rapid precise orbit siowwwwd.sp3 - final precise orbit siopoleut.rapid - pole estimates Notes: (1) NGS SP3 format (e.g., sioWWWWd.sp3) is the recognized orbit exchange format adopted by the IGS. (2) To access SOPAC GARNER archive: ftp toba.ucsd.edu (132.239.152.80) login: anonymous password: your e-mail address Direct problems to: pgga at pgga.ucsd.edu Geodesy Lab Tel: +1 619 534-7692 Fax: +1 619 534-9873 WWW Home Page - http://toba.ucsd.edu (3) The siopoleut.rapid file contains UT values. These are NOT estimated values, they are IERS Bulletin A predicted values. (4) SIO uses GAMIT/GLOBK software which has recently undergone much development. Thanks are extended to Bob King, Tom Herring and Simon McClusky (MIT) for their efforts in this regard. Disclaimers: (1) These SOPAC products are intended for near-real time scientific, non-commercial applications. They are not intended to replace the official IGS rapid orbit. (2) Due to the automatic nature of these products, SOPAC is not responsible for their accuracy, reliability and availability. However, all care will be taken to maintain the accuracy of the products. [Mailed From: pgga at pgga.UCSD.EDU (Geodesy Lab account)]