Author: AC Coordinator / GFZ Potsdam Ultra Rapid IGS Orbit Combination - Week 1266 Day: 3 Hour: 12 (Apr 14, 2004) Contacts: G. Gendt (gendt@gfz-potsdam.de), Th. Nischan (nisn@gfz-potsdam.de) COMBINATION STRATEGY: For a complete description of the combination strategy along with all tables and statistics, please refer to the IGS Final Combination reports posted on CDDIS within 13 days after the end of the GPS week. REMARKS on IGS Ultra Rapid Orbit Combination: 1. The following centre clock solutions, which provide broadcast and/or predicted clock corrections, were excluded from the combination but kept in the combination statistics: -> Centre: COU GOU 2. The following orbit solutions were excluded from the combination because they were biasing the weighted average. They were still used for statistics computation unless all centres were excluded for the problem satellites in which case they were simply eliminated from the combination and statistics. The following table lists the exclusions: Centre | PRN list -------+--------------- SIU | 7 EMU | 24 3. The following orbit solutions were rejected from the combination due to lack of redundancy, i.e. not enough centres providing a solution (=> Minimum number of centres: 3): Centre | PRN -------+----- COU | 6 4. Starting on 11-Jan-2004 (GPS Week 1253, day 0, MJD 53015) all IGS products, including the IGS combined orbits, are based on the IGS realization of the ITRF2000 reference frame (IGb00). For more information see IGSMAIL #4748. _______________________________________________________________________________ Table 1: Daily transformation of each centre to the combined IGS orbit and clocks. WRMS - RMS weighted by the centres SP3 header accuracy codes. STA - Number of stations in the daily solutions. Units: meters, mas, ppb, nano-sec, nano-sec/day. Table 1.1266.3 GPS week: 1266 Day: 3 MJD: 53109.500 CENT STA| DX DY DZ RX RY RZ SCL RMS WRMS | TOFT TDRFT RMS --------|------------------------------------------------|--------------------- cou 114|0.00 0.00 0.00 -0.02 0.15 -0.11 -0.1 0.06 0.05 | -4.9 -1.5 121.80 emu 50 |0.00 0.00 0.00 -0.33 0.24 0.21 0.3 0.20 0.09 | 128.4 -122.6 223.40 gfu 56 |0.00 0.00 0.00 0.00 -0.18 -0.51 0.0 0.08 0.05 | -4.7 0.6 121.10 gou 62 |0.00 0.00-0.01 0.45 -0.25 0.07 0.0 0.11 0.10 | -5.1 -1.1 124.20 siu 38 |0.00 0.00 0.01 -0.14 -0.07 1.34 0.1 0.56 0.11 | 0.0 0.0 0.00 Table 2: Daily fit for each satellite and each centre resulting from weighted average combination. The last column gives the IGS resulting satellite accuracy measures found in the IGS SP3 header. Eclipsing satellites are flagged with and "E" beside the PRN number. "X" stands for excluded from RMS, WRMS and MEDIan- combination statistics but included in IGU orbit. "MEDI" stands for median of the centre's satellite RMS. Units: cm. Table 2.1266.3 GPS week: 1266 Day: 3 MJD: 53109.500 Weighted Average PRN | cou emu gfu gou siu IGU | ------|--------------------------| 1 | 11 8 6 5 12 4 | 3 | 6 6 5 3 9 3 | 4 | 6 4 3 8 30 5 | 5 | 2 4 6 9 9 3 | 7 | 6 18 20 28 268 11 | 8 | 5 7 4 4 14 3 | 9 | 4 5 4 10 11 3 | 10 | 4 4 3 7 15 3 | X11 | 4 7 7 --- 21 5 | 13 | 6 7 4 7 14 3 | 14 | 3 10 3 6 14 3 | 15 | 3 5 4 4 12 3 | 16 | 3 11 4 5 11 3 | 17 | 4 5 4 7 7 2 | 18 | 3 13 3 18 19 5 | 19 | 7 18 9 7 10 5 | 20 | 5 15 6 10 8 4 | 21 | 4 9 3 6 26 5 | 22 | 4 10 5 9 12 4 | 24 | 19 90 24 30 37 15 | 25 | 4 14 4 5 10 4 | 26 | 5 6 3 14 13 4 | 27 | 3 6 4 5 13 3 | 28 | 4 5 4 7 18 3 | X29 | 9 --- 6 10 --- 6 | 30 | 4 9 7 10 8 4 | 31 | 3 8 5 5 8 3 | ------|--------------------------| RMS | 6 20 8 11 56 | WRMS | 5 9 5 10 11 | MEDI | 4 8 4 7 13 | Table 3: Earth Orientation Parameters daily summary. Daily Centre ERP, ERP Rates and LOD differences with respect to IGU combined values. Xpole,Xrt: x pole and x pole rate (10**-5") Ypole,Yrt: y pole and y pole rate (10**-5"/day) LOD: Length Of Day (us) AC LOD BIAS: 21-day mean LOD bias with respect to Bulletin A (us) AC LOD BIAS RMS: RMS of AC LOD BIAS (us) FLAG: "u" (used), "x" (excluded), "-" (no submission) for Xpole, Ypole, Xrt, Yrt and LOD A star ("*") beside the AC name indicates that AC LOD values were derived from AC UT1-UTC values. Table 3.1266.3 GPS week: 1266 Day: 3 MJD: 53109.000 AC LOD AC LOD CENT FLAG | Xpole Ypole Xrt Yrt LOD | BIAS BIAS RMS ------------------------------------------------------------------------ cou uuuuu | -16 11 -3 -17 3 | -10 17 emu uuuuu | -12 30 -39 25 -6 | 5 29 gfu uuuuu | 11 -1 28 6 6 | 15 23 gou uuuuu | 19 -57 -14 -6 -58 | -23 51 siu uuuuu | 11 8 24 -3 45 | -52 74 Table 3.1266.4 GPS week: 1266 Day: 4 MJD: 53110.000 AC LOD AC LOD CENT FLAG | Xpole Ypole Xrt Yrt LOD | BIAS BIAS RMS ------------------------------------------------------------------------ cou uuuuu | -28 -34 1 -6 18 | -10 17 emu uuuuu | -36 53 -18 2 -65 | 5 29 gfu uuuuu | 29 17 11 3 4 | 15 23 gou uuuuu | 34 -37 8 5 34 | -23 51 siu uuuuu | 13 18 -21 -2 -7 | -52 74