Author: AC Coordinator / NRCan GSDivision Rapid IGS Orbit Combination - Week 0914 Day: 2 (Jul 15, 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. Starting on June 30, 1996 all IGS products, including the IGS combined orbits, are based on ITRF94. 6. 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 1.0914.2 GPS week: 0914 Day: 2 MJD: 50644.0 CENT STA| DX DY DZ RX RY RZ SCL RMS WRMS | TOFT TDRFT RMS --------|------------------------------------------------|--------------------- brd n/a| .12 .04 .18 2.98 -9.09 6.17 -2.7 3.42 3.42 | 1.4 -6.8 77.7 cod 77 |-.03 .05 -.03 -.61 -.31 .38 .2 .27 .14 | .9 -6.3 77.9 emr 21 |-.02 .05 .01 .38 .36 .33 -.2 .16 .13 | 1275.2 69.2 .3 gfz 31 | .00 -.01 .01 -.24 .12 -.21 -.2 .06 .06 | 1277.5 69.3 .3 igp n/a| .01 .02 -.01 .83 -.50 -1.77 -.4 2.81 1.15 | 5.7 -12.2 83.2 ngs 56 | .01 -.02 -.02 .74 .32 -.39 .1 .28 .27 | 1.6 -5.9 77.8 sio 51 | .00 .05 -.01 -1.46 -.02 -.72 .2 .47 .47 | .0 .0 .0 usn 25 | .01 -.05 -.01 .52 -.41 .18 .4 .10 .11 | 1276.8 68.7 .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 2.0914.2 GPS week: 0914 Day: 2 MJD: 50644.0 Weighted Average PRN | brd cod emr gfz igp ngs sio usn IGS | ------|--------------------------------------| 1 | 106 11 10 8 15 27 20 16 6 | 2 | 156 17 11 6 48 22 10 9 5 | 3 | 112 20 8 8 12 23 16 9 5 | 4 | 250 29 12 6 14 62 40 10 10 | 5 | 221 11 25 11 14 23 25 9 7 | 6 | 412 14 17 6 11 22 24 17 6 | 7 | 226 17 9 5 18 25 52 7 7 | 9 | 79 15 17 7 10 41 13 9 7 | 10E | 226 12 15 9 38 38 15 5 6 | 14E | 398 9 26 5 279 29 --- 8 7 | 15 | 132 23 9 7 12 10 12 10 5 | 16E | >>> 105 46 --- >>> --- 195 --- 73 | 17 | 112 11 6 4 19 18 9 6 3 | 18 | 367 21 11 5 46 25 38 6 6 | 19 | 169 18 9 4 35 20 35 8 5 | 21E | 232 14 12 3 145 15 19 8 4 | 22 | 216 22 6 9 13 20 12 14 6 | 23E | 245 19 13 8 837 38 25 16 7 | 24 | 498 14 12 6 12 45 22 7 7 | 25 | 241 10 6 5 14 12 27 6 4 | 26 | 151 28 9 5 17 22 8 10 6 | 27 | 137 12 14 5 24 18 17 7 4 | 29 | 227 12 12 4 20 17 46 7 6 | 30 | 113 8 8 8 42 15 17 16 5 | 31 | 47 25 7 5 11 19 13 10 5 | ------|--------------------------------------| RMS | 342 27 16 6 281 28 47 10 | WRMS | 342 14 13 6 115 27 47 11 | MEDI | 221 15 11 6 18 22 20 9 | 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 3.0914.2 GPS week: 0914 Day: 2 MJD: 50644.0 CENT| CLK EPO | WILL | ----|----------|----------------| emr | emr 2369 | 25 18 53 | gfz | gfz 1135 | 32 22 54 | igr | igr 2397 | 25 17 56 | usn | usn 2282 | 26 15 56 |