Author: AC Coordinator / AIUB/CODE Rapid IGS Orbit Combination - Week 1084 Day: 5 (Oct 20, 2000) Contacts: T.A. Springer (springer@aiub.unibe.ch) H. Bock (bock@aiub.unibe.ch), R. Dach (dach@aiub.unibe.ch) 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 11 days after the end of the GPS week. REMARKS on IGS Rapid Orbit Combination: 1. Broadcast ("brd") orbits/clocks are included in the combination for statistics only. However broadcast clock corrections are used for clock alignment to GPS time and centre clock weight determination purposes. 2. The following IGR 2-day prediction and IGU Ultra rapid 1-day prediction orbits/clocks were excluded from the combination but kept for statistics: -> Centre: IGP IGU 3. The following centre clock solutions, which provide broadcast clock corrections, were excluded from the combination but kept in the combination statistics: -> Centre: NGS COD 4. Centre clock weights were determined using the following satellites: PRN list | Ref. Centre ----------+------------ All | USN (see note below) Note: A chosen reference centre is aligned to the broadcast GPS clocks using all satellites; all other centres are then aligned to that reference centre. The clock weights are computed from the absolute deviation of centre's aligned clock corrections with respect to the unweighted mean. 5. The following clock solutions were excluded from the combination because they were biasing the combined clock solutions. Centre | PRN list -------+--------------- JPL | 28 JPL | ALL 6. Starting on 04-June-2000 (GPS Week 1065, day 0, MJD 51699) all IGS products, including the IGS combined orbits, are based on the IGS realization of the ITRF97 reference frame (IGS97). For more information see IGSMAILs #2899 and #2904. 7. In the navigation solution there is an additional solution labeled "igc". The orbit of this solution is the same as the orbit of the "igs" solution. The clocks, however, are based on a new clock combination scheme which uses the clock RINEX files as input if available, otherwise SP3 clocks are used. In the near future this "igc" clock solution will replace the "igs" solution but for now it is included for test purposes only. 8. Starting on 29-Nov-1998 (GPS Week 986, day 0; mjd=51146) all IGS clock products reflect the use of the following antenna phase center offsets (satellite fixed reference frame): Block II/IIA: 0.279 0.000 1.023 X, Y, Z in meters Block IIR : 0.000 0.000 0.000 X, Y, Z in meters _______________________________________________________________________________ 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 1.1084.5 GPS week: 1084 Day: 5 MJD: 51837.0 CENT STA| DX DY DZ RX RY RZ SCL RMS WRMS | TOFT TDRFT RMS --------|------------------------------------------------|--------------------- brd n/a|0.01 0.02 0.04 -2.10 1.48 4.12 3.9 2.26 2.26 | 0.9 -1.7 7.0 cod 109|0.00 0.00 0.00 -0.11 -0.14 0.03 0.0 0.04 0.03 | 1.4 0.8 0.3 esa 45 |0.00 0.01 0.01 0.07 -0.04 -0.05 0.2 0.07 0.06 | 1689.0 6.5 0.2 igp n/a|0.00 0.00-0.01 -0.29 0.16 -0.03 0.4 3.59 2.50 |-9600.015482.299999.9 igu n/a|0.01 0.01-0.01 0.18 0.39 0.89 0.7 0.28 0.15 |-6205.3 4998.7 10.0 jpl 21 |0.00 0.00 0.00 0.10 -0.06 -0.12 0.1 0.05 0.05 | -0.2 1.8 0.4 ngs 47 |0.00 0.00 0.00 -0.18 -0.22 0.01 -0.2 0.10 0.10 | 1.2 -2.0 6.7 sio 39 |0.00 0.00 0.00 -0.20 0.12 -0.02 -0.6 0.05 0.05 | 0.0 0.0 0.0 usn 34 |0.00 0.00-0.01 0.20 0.23 -0.01 0.3 0.05 0.05 | 1702.0 6.5 0.2 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 combination but included in IGS orbit. "MEDI" stands for median of the centre's satellite RMS. Units: cm. Table 2.1084.5 GPS week: 1084 Day: 5 MJD: 51837.0 Weighted Average PRN | brd cod esa igp igu jpl ngs sio usn IGR | ------|------------------------------------------| 1 | 211 3 4 24 8 3 6 3 4 2 | 2E | 228 4 5 81 31 7 12 6 5 3 | 3 | 125 2 6 79 8 3 13 4 4 2 | 4 | 153 4 5 10 15 4 5 4 7 2 | 5E | 240 3 11 39 35 3 13 5 6 3 | 6 | 263 5 8 18 14 4 10 4 4 2 | 7 | 133 3 4 10 14 5 5 4 4 2 | 8 | 130 4 4 12 13 3 6 5 4 2 | 9 | 113 3 3 16 22 3 7 4 4 2 | 10 | 151 4 7 7 28 3 6 7 5 2 | 11 | 461 3 15 15 6 7 18 4 6 4 | 13 | 273 4 5 28 11 4 9 6 4 2 | X15 | 247 3 --- --- 7 3 6 5 4 2 | 17 | 249 3 5 24 12 3 6 6 5 2 | 19 | 310 3 8 >>> 66 4 5 5 6 2 | 20 | 120 4 5 23 15 9 20 6 5 4 | 21 | 165 2 5 30 8 5 7 6 4 2 | 22E | 153 4 9 68 15 4 10 5 4 3 | 23 | 533 11 15 --- 86 9 8 11 9 5 | 24 | 286 4 4 16 13 3 7 5 5 2 | 25 | 160 2 6 9 12 5 10 4 5 2 | 26 | 75 5 9 34 7 7 7 6 4 3 | 27 | 113 3 5 19 9 3 7 4 4 2 | 28E | 123 3 8 48 12 6 17 5 3 3 | 29 | 165 2 5 15 7 4 8 5 5 2 | 30E | 109 5 9 72 54 5 8 7 5 3 | 31 | 144 2 5 21 6 5 9 3 5 2 | ------|------------------------------------------| RMS | 226 4 7 359 28 5 10 5 5 | WRMS | 226 3 6 249 15 5 10 5 5 | MEDI | 160 3 5 23 13 4 8 5 5 | Table 3: Daily Precise Navigation Summary using the corresponding Centre orbit positions and satellite clock corrections at 15 min intervals. Each line gives the daily station RMS w.r.t. the estimated coordinates for the Latitude, Longitude and Height components. CLK - Satellite clocks used. EPO - Number of satellite clock epochs available for that day. Units: centimetres. Table 3.1084.5 GPS week: 1084 Day: 5 MJD: 51837.0 CENT| CLK EPO | BRUS | TOW2 | WILL | ----|----------|----------------|----------------|----------------| esa | esa 2453 | 2 2 5 | 1 3 4 | 6 4 11 | igc | igc 2354 | 3 2 4 | 2 2 5 | 2 2 5 | igr | igr 2575 | 2 2 4 | 2 2 5 | 3 3 7 | jpl | jpl 2567 | 2 2 4 | 1 1 5 | 3 3 6 | usn | usn 2570 | 2 1 4 | 2 3 5 | 3 3 7 | Table 4: Earth Orientation Parameters daily summary. Daily Centre ERP, ERP Rates and LOD differences with respect to IGR 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 4.1084.5 GPS week: 1084 Day: 5 MJD: 51837.5 AC LOD AC LOD CENT FLAG | Xpole Ypole Xrt Yrt LOD | BIAS BIAS RMS ------------------------------------------------------------------------ cod uuuuu | 16 14 37 8 -10 | 22 42 esa uuuuu | -2 -9 -37 -8 5 | 43 47 igu xxxxx | -44 -9 -2 4 -36 | 46 59 jpl uuuuu | 6 -13 52 7 -31 | 40 54 ngs uuuuu | 14 27 78 -15 -19 | 43 63 sio uuuuu | -20 12 -78 23 22 | -17 33 usn uuuuu | -12 -22 -37 -28 -2 | 54 59