Author: AC Coordinator / NRCan GSDivision Rapid IGS Orbit Combination - Week 0914 Day: 0 (Jul 13, 1997) Contacts: J. Kouba (kouba@geod.emr.ca), Y. Mireault (mireault@geod.emr.ca) 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 orbits/clocks were excluded from the combination but kept for statistics: -> Centre: IGP 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 non-SA satellites: PRN15. 5. The following clock solutions were excluded from the combination because they were biasing the combined clock solutions. Centre | PRN list -------+--------------- ESA | ALL 6. 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 -------+--------------- SIO | ALL (high Rotations - See Table 1) 7. Starting on June 30, 1996 all IGS products, including the IGS combined orbits, are based on ITRF94. 8. Starting with GPS wk 0895, IGS LOD combinations were implemented in the Rapid IGS solutions. AC LOD biases with respect to Bulletin A are estimated using Bulletin A most recent 3 weeks (21 days), i.e. up to 5 days prior to the last non-predicted day of Bulletin A. AC LOD biases are removed and the new AC bias-free LODs are used to compute a weighted IGS LOD which in turn is used to integrate UT1-UTC. The starting UT1-UTC value is chosen as Bulletin A fifth day prior to its last non-predicted day. _______________________________________________________________________________ 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 1.0914.0 GPS week: 0914 Day: 0 MJD: 50642.0 CENT STA| DX DY DZ RX RY RZ SCL RMS WRMS | TOFT TDRFT RMS --------|------------------------------------------------|--------------------- brd n/a| .00 .14 .28 4.90 -8.80 6.65 -3.2 3.12 3.12 | 5.7 -7.0 78.9 cod 66 |-.01 .03 -.02 -.57 .24 -.03 .0 .08 .07 | 5.1 -5.1 79.1 esa 48 | .00 .03 .00 -.13 -.30 -.05 .1 .08 .08 | 21.7 -54.9 13.2 gfz 30 |-.02 -.02 .01 -.28 -.12 -1.23 -.2 .09 .09 | 1113.3 76.0 .3 igp n/a|-.02 .02 .00 1.52 .84 -5.55 -.6 2.00 .35 | 3.1 -8.5 87.6 jpl 21 | .02 .02 .01 .46 -.20 .61 .3 .08 .08 | 3.8 -1.3 .3 ngs 53 |-.01 -.04 -.02 .33 .28 .08 -.2 .18 .19 | 1091.6-1718.918120.0 sio 49 |-.02 .02 .01 -.69 .28 -6.08 -.8 .15 .15 | .0 .0 .0 usn 25 | .01 -.06 .01 .72 .23 .80 .4 .11 .11 | 1112.5 75.3 .3 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. "MEDI" stands for median of the centre's satellite RMS. Units: cm. Table 2.0914.0 GPS week: 0914 Day: 0 MJD: 50642.0 Weighted Average PRN | brd cod esa gfz igp jpl ngs sio usn IGS | ------|------------------------------------------| 1 | 184 13 11 11 64 8 28 13 8 6 | 2 | 121 12 8 11 15 7 10 14 9 4 | 3 | 134 6 6 10 18 11 12 14 11 4 | 4 | 200 5 6 10 18 5 18 13 10 4 | 5 | 331 8 9 6 12 8 11 15 11 4 | 6 | 306 8 9 7 14 7 12 16 11 4 | 7 | 463 10 8 8 10 7 17 14 13 4 | 9 | 108 5 7 9 63 4 9 16 13 4 | 10E | 304 6 9 7 27 7 33 15 10 5 | 14E | 321 9 7 9 51 7 12 17 16 4 | 15 | 342 10 8 8 40 7 18 17 11 4 | 16E | 471 7 9 12 495 9 14 --- 12 5 | 17 | 175 7 5 5 14 7 6 14 7 3 | 18 | 314 6 10 8 24 7 14 11 14 4 | 19 | 316 9 5 4 52 5 18 16 8 4 | 21E | 268 9 12 7 72 8 23 11 14 5 | 22 | 201 7 7 11 25 7 12 17 11 4 | 23E | 735 9 7 10 849 13 41 22 11 7 | 24 | 372 7 11 10 14 6 25 10 9 5 | 25 | 255 5 6 9 14 9 13 17 6 4 | 26 | 142 3 13 15 65 9 10 16 10 5 | 27 | 117 7 5 6 23 9 15 16 8 4 | 29 | 361 7 7 7 67 7 19 13 10 4 | 30 | 152 5 6 7 54 7 11 16 10 3 | 31 | 289 9 9 8 15 9 15 16 14 4 | ------|------------------------------------------| RMS | 312 8 8 9 200 8 18 15 11 | WRMS | 312 7 8 9 35 8 19 15 11 | MEDI | 289 7 8 8 25 7 14 16 11 | 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 initial 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 3.0914.0 GPS week: 0914 Day: 0 MJD: 50642.0 CENT| CLK EPO | BRUS | USUD | WILL | ----|----------|----------------|----------------|----------------| esa | esa 2036 | 0 0 0 | 35 23 76 | 21 17 48 | gfz | gfz 1197 | 0 0 0 | 27 17 78 | 21 18 45 | igr | igr 2389 | 0 0 0 | 28 20 66 | 19 13 47 | jpl | jpl 2378 | 0 0 0 | 28 19 68 | 19 13 44 | usn | usn 2377 | 0 0 0 | 28 23 66 | 20 12 48 |