From Analysis Thu Mar 10 11:52:28 1994 From: Analysis (Analysis) Date: Thu, 10 Mar 1994 11:52:28 PST Subject: [IGSREPORT-0835] IGS Final Orbit Comb(732) Message-ID: ****************************************************************************** IGS Electronic Report Thu Mar 10 11:52:28 PST 1994 Message Number 0835 ****************************************************************************** Author: Analysis Centres Coordinator / Geodetic Survey of Canada Subject: IGS Final Orbit Comb(732) IGS Final Orbit Combination Week 0732 (Jan 16, 1994 - Jan 22, 1994) Contacts: F. Lahaye (lahaye at geod.emr.ca), J. Kouba (kouba at geod.emr.ca) COMBINATION STRATEGY: For a complete description of the combination strategy, see IGSMAIL #832. SOFTWARE: The weighted average software used was developed by T. Springer and G. Beutler during 1993. The GPS long arc orbit analysis software used here for individual centre ephemeris evaluation was developed by Beutler et al. at the Astronomical Institute of the University of Bern (AIUB). For more details on the orbit combination and complete references for both software see: Beutler, Kouba, Springer, 1993, Combining orbits of the IGS processing centres, in IGS Analysis Centre Workshop, October 12-14, Ottawa, pp 19-55. PRODUCTS GENERATED: The resulting average ephemeris and clocks are output to daily files in SP3 format. The satellite accuracy codes displayed in the header are based on the weighted RMS for each satellite. Note that each file contains all the satellites that appear in any of the centre ephemeris files. If a satellite or centre was excluded from combination, a note in the REMARKS section of this report will identify the exclusion and the reason. The IGS Final Orbit files generated and uploaded into CDDIS @ NASA/GSFC are: IGS07320-6.SP3 IGS GPS ephemeris files for days 0-6, week 0732 in SP3 format. IGS07327.ERP Earth rotation parameters (ERP) associated with ephemerides. IGS07327.SUM Complete report. The old Rapid Service files have been renamed to: IGR07320-6.SP3 Rapid Service ephemeris files for days 0-6. IGR07327.ERP Rapid Service earth rotation parameters (ERP). IGR07327.SUM Rapid Service complete report. REMARKS on IGS Final Orbit Combination: 1. Only the GFZ "exact" clock corrections (one epoch out of two) are included in the combination and RMS computation (no "interpolation" values). 2. ESA satellite clock corrections were not incuded in the combination since they exhibit systematic effects at the 10 nano-seconds level due to not accounting for relativistic effects. 3. The large clock correction RMS for COD on day 6 (Jan 22) is due to a delay in acknowledging a large (14 micro-sec.) clock reset on PRN 03 by broadcast message (ref NANU 028-94024). Since the COD clock solution is not included in the combination, the IGS clocks are not affected and are aligned to the EMR clocks. The resulting alignment to GPS time is better than what is shown i.e. an offset of -17.5 nanosec and a drift of -6.9 nanosec/day. 4. A maneuvre for PRN17 on days 4 and 5 (Jan 20-21) (ref NANU 003-94007). It was not included in combination on day 4 (Jan 20). 5. In the long arc analysis, state vector resets were modeled for PRN17 on day 5 (Jan 21) (maneuvre) and for PRN22 on day 3 (Jan 19). ORBIT COMBINATION AND EVALUATION STATISTICS: For a complete description of tables and statistics, see IGSMAIL #832. Table 1: Week 0732 summary. (Jan 16, 1994 - Jan 22, 1994) Table 1.0732.a GPS week: 0732 MJD: 49368.0-49374.0 Mean and standard deviations of transformation parameters. WRMS - orbit RMS weighted by the SP3 header accuracy codes. Units: meters, mas, ppb, nano-sec, nano-sec/day. CENT| DX DY DZ RX RY RZ SCL RMS WRMS | TOFT TDRFT RMS ----|---------------------------------------------------|--------------------- cod | .01 .01 .02 1.16 .19 -.09 .0 .11 .11 | .2 -.8 74.6 | .00 .01 .01 .28 .69 .25 .1 | 1.4 2.1 emr | .01 -.01 -.01 2.21 .62 -.19 -.3 .12 .12 | -294.0 -13.0 .9 | .01 .00 .00 .30 .48 .17 .1 | 305.3 19.8 esa | .00 .00 .01 1.42 .12 -.86 -.1 .19 .17 | 1.6 -4.1 14.0 | .01 .01 .01 .26 .75 .63 .2 | 18.9 3.6 gfz | -.04 .00 .01 1.27 1.42 -.88 -.4 .13 .13 | 35.7 -11.2 9.4 | .01 .00 .01 .16 .51 .28 .1 | 35.2 28.1 jpl | -.01 .04 .00 1.15 .18 -.26 .2 .12 .13 | 35.8 -10.7 .9 | .01 .01 .01 .17 .55 .26 .1 | 35.9 30.3 ngs | .02 -.05 .01 1.11 -.07 .39 2.0 .28 .27 | .0 .0 .0 | .01 .02 .03 .40 .85 .26 .5 | .0 .0 sio | .02 -.05 -.05 2.11 .60 2.49 .4 .18 .18 | .0 .0 .0 | .01 .01 .01 .20 .35 1.17 .1 | .0 .0 Table 1.0732.b GPS week : 0732 MJD: 49368.0-49374.0 Satellite position sigmas for the combined orbits (coded in the IGS SP3 orbit files). "E" flags eclipsing satellites. Units: cm. Day of GPS week PRN | 0 1 2 3 4 5 6 | Remarks ------|-----------------------------|------------------------------------------ 1 | 6 7 4 5 5 4 5 | 2E | 7 8 8 9 8 9 9 | 3 | 4 5 5 5 4 6 7 | 4E | 7 7 5 7 6 6 7 | 5E | 8 9 7 10 9 8 9 | 7 | 5 6 5 6 5 4 6 | 9 | 5 5 4 5 5 5 4 | 12 | 5 4 5 5 4 4 4 | 13 | 6 5 5 6 4 4 6 | 14 | 5 5 4 4 4 5 4 | 15E | 5 4 4 5 5 6 5 | 16 | 6 7 5 7 7 5 6 | 17E | 5 5 5 7 --- 10 6 | Maneuvre on days 4 and 5 (Jan 20-21). 18 | 4 4 4 4 3 4 4 | 19 | 4 4 4 6 5 5 5 | 20E | 7 6 7 6 7 8 8 | 21 | 5 5 4 5 5 4 6 | 22E | 6 8 5 7 9 6 8 | 23 | 7 5 7 4 6 7 6 | 24E | 7 6 5 7 7 6 --- | 25 | 7 6 6 7 6 5 7 | 26 | 6 5 5 6 5 5 6 | 27 | 4 4 4 6 5 5 5 | 28 | 4 5 4 5 5 4 4 | 29 | 4 4 4 4 4 4 4 | 31 | 6 6 6 5 4 5 4 | For tables 2 and 3, please refer to the complete report (IGS07327.SUM) posted on CDDIS.