Author: AC Coordinator / NRCan GSDivision Rapid IGS Orbit Combination - Week 0914 Day: 1 (Jul 14, 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 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) 6. Starting on June 30, 1996 all IGS products, including the IGS combined orbits, are based on ITRF94. 7. 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 1.0914.1 GPS week: 0914 Day: 1 MJD: 50643.0 CENT STA| DX DY DZ RX RY RZ SCL RMS WRMS | TOFT TDRFT RMS --------|------------------------------------------------|--------------------- brd n/a|-.11 .01 .28 3.53 -6.56 2.24 -4.9 2.96 2.96 | 3.7 -19.8 78.9 cod 66 |-.01 .05 -.01 -.80 -.30 .11 -.2 .16 .08 | 3.7 -19.7 78.9 emr 22 |-.01 .02 -.02 .55 .36 -.29 .0 .16 .15 | 1192.2 59.8 .5 esa 54 | .00 .01 .00 .00 -.56 .05 .2 .21 .12 | -20.9 -60.5 1.7 gfz 29 |-.02 -.02 .01 -.16 .08 -.52 -.1 .07 .07 | 1193.8 60.1 .5 igp n/a| .02 .02 -.03 .50 -.28 -3.32 -.2 1.39 .44 | -4.3 -28.1 85.5 jpl 21 | .00 .02 .01 .14 .15 .45 .2 .14 .14 | -.8 -21.7 .5 ngs 52 | .03 -.04 .00 .37 .04 .75 .0 .25 .20 | 3789.7-6390.328840.0 sio 51 | .00 .02 -.01 -.48 .12 -4.95 -.9 .23 .23 | .0 .0 .0 usn 25 | .04 -.05 -.01 .81 .17 .30 -.1 .20 .20 | 1193.4 60.0 .7 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 2.0914.1 GPS week: 0914 Day: 1 MJD: 50643.0 Weighted Average PRN | brd cod emr esa gfz igp jpl ngs sio usn IGS | ------|----------------------------------------------| 1 | 290 8 12 9 5 36 7 14 18 14 4 | 2 | 251 11 12 13 10 20 8 23 17 13 5 | 3 | 137 8 14 9 7 22 8 19 20 12 4 | 4 | 154 10 38 15 7 31 22 24 16 25 8 | 5 | 168 7 11 8 10 37 10 17 13 9 4 | 6 | 364 9 12 9 6 12 6 17 14 12 4 | 7 | 124 20 18 10 7 14 18 22 16 30 7 | 9 | 90 7 15 8 6 13 8 11 19 13 4 | 10E | 218 10 17 16 8 145 10 19 10 16 5 | 14E | 556 12 16 12 10 105 9 25 27 12 5 | 15 | 185 9 11 11 5 32 8 12 16 15 4 | 16E | 430 67 33 91 --- 449 55 77 87 66 30 | 17 | 482 6 15 4 7 13 6 17 12 8 4 | 18 | 354 10 12 19 7 68 11 25 17 29 6 | 19 | 653 10 9 5 5 62 5 22 18 13 4 | 21E | 145 10 11 13 6 153 10 15 12 19 5 | 22 | 180 8 15 5 6 13 5 18 16 14 4 | 23E | 207 10 12 8 7 453 6 28 18 16 5 | 24 | 249 7 11 22 8 12 7 34 14 10 6 | 25 | 352 9 7 7 6 15 7 13 14 21 4 | 26 | 176 9 8 19 11 33 8 16 13 8 5 | 27 | 85 10 15 6 9 11 6 14 15 10 4 | 29 | 335 6 13 9 6 24 6 22 19 13 4 | 30 | 144 6 14 10 7 9 7 14 11 12 4 | 31 | 92 9 7 7 8 13 8 23 15 11 4 | ------|----------------------------------------------| RMS | 296 16 16 21 7 139 14 25 23 20 | WRMS | 296 8 15 12 7 44 14 20 23 20 | MEDI | 207 9 12 9 7 24 8 19 16 13 | 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 3.0914.1 GPS week: 0914 Day: 1 MJD: 50643.0 CENT| CLK EPO | USUD | WILL | ----|----------|----------------|----------------| emr | emr 2388 | 36 24 60 | 21 13 47 | esa | esa 2224 | 42 27 70 | 23 18 53 | gfz | gfz 1143 | 42 32 67 | 24 15 56 | igr | igr 2400 | 34 22 55 | 21 13 45 | jpl | jpl 2379 | 33 23 56 | 20 13 45 | usn | usn 2370 | 38 24 65 | 23 14 50 |