Author: AC Coordinator / AIUB/CODE Rapid IGS Orbit Combination - Week 1053 Day: 4 (Mar 16, 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 | GFZ (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 -------+--------------- ESA | ALL JPL | 11 26 30 6. New clock offsets and drifts were estimated for centres showing reference clock resets. Note that only the first clock offset and drift are output to the summary file. However, the clock combination and the listed RMS include all the clock segments. In summary, the following clock shifts/resets were noticed and accounted for: Centre | Time | Jump -------+--------+------------- JPL | ~11:45 | ~ -28.1 ns 7. 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 -------+--------------- JPL | 30 ESA | 23 SIO | ALL (high Transformation - See Table 1) 8. Starting on 01 August 1999 (GPS Week 1021, day 0, mjd=51391) all IGS products, including the IGS combined orbits, are based on ITRF97. 9. Starting on 1998-Nov-29 (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 1.1053.4 GPS week: 1053 Day: 4 MJD: 51619.0 CENT STA| DX DY DZ RX RY RZ SCL RMS WRMS | TOFT TDRFT RMS --------|------------------------------------------------|--------------------- brd n/a|-.03 0.11 0.25 -1.02 1.90 13.46 -0.1 3.23 3.23 | -17.6 22.1 151.9 cod 96 |0.00 0.00 0.01 -0.08 -0.05 -0.08 -0.2 0.06 0.05 | -18.0 23.2 172.7 emr 28 |-.01 0.03-0.02 -0.52 -0.94 0.23 0.0 0.11 0.11 |-2555.0 -3.4 0.2 esa 45 |0.01 0.00-0.02 -0.02 0.35 -0.34 0.3 0.17 0.09 |-2558.9 -2.8 1.9 gfz 33 |-.01-0.01 0.01 0.17 0.32 0.22 -0.1 0.08 0.07 | 0.7 -4.6 0.3 igp n/a|-.01 0.00-0.02 1.38 0.71 1.24 -0.1 0.40 0.28 | -5.7 -25.9 93.5 igu n/a|0.02 0.00 0.01 0.94 0.88 0.61 -0.4 0.95 0.21 | 0.0 0.0 0.0 jpl 20 |0.02 0.00 0.02 0.26 0.03 -0.25 0.1 0.19 0.19 | -20.3 118.5 1.0 ngs 49 |0.01 0.02-0.01 0.08 0.01 -0.13 0.1 0.12 0.12 | -24.4 33.2 140.9 sio 52 |0.01 0.01-0.01 -0.07 0.35 -1.30 -0.7 0.12 0.09 | 0.0 0.0 0.0 usn 33 |0.00-0.01-0.01 -0.07 0.34 0.17 0.4 0.11 0.08 | 857.7 7.9 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 2.1053.4 GPS week: 1053 Day: 4 MJD: 51619.0 Weighted Average PRN | brd cod emr esa gfz igp igu jpl ngs sio usn IGR | ------|--------------------------------------------------| 1 | 190 4 8 8 5 9 23 5 7 5 9 3 | 2 | 170 5 13 21 7 11 6 8 13 9 7 4 | 3 | 109 5 11 8 6 22 25 5 11 10 9 3 | 4E | 405 5 11 10 5 56 23 5 19 5 7 4 | 5 | 202 4 8 12 8 16 12 10 8 7 7 3 | 6 | 214 4 8 4 4 22 12 17 16 6 7 4 | 7 | 115 5 13 8 9 9 23 7 9 5 10 3 | 8E | 226 5 7 9 8 40 30 5 14 7 7 3 | 9E | 162 4 11 12 6 72 28 8 8 8 7 3 | 10 | 198 5 11 14 6 9 10 7 10 7 6 3 | 11E | 436 6 14 14 6 7 34 15 16 26 28 6 | 13 | 93 7 12 8 8 43 14 6 8 8 8 3 | 14 | 311 4 9 9 5 --- 13 6 9 --- 9 3 | 15E | 554 12 15 22 21 --- 381 17 14 38 33 8 | 16 | 773 5 10 8 5 35 20 9 14 10 14 4 | 17E | 161 4 10 9 4 25 31 10 9 10 8 3 | 18 | 452 8 8 7 7 --- 147 5 10 10 11 3 | 19E | 168 6 7 14 9 90 35 5 10 9 9 3 | 21 | 112 6 16 8 6 10 47 7 6 8 6 3 | 22 | 187 5 9 8 4 52 54 10 10 9 7 3 | 23 | 265 6 13 67 7 --- 253 10 13 12 8 11 | 24E | 427 3 10 13 12 117 73 7 15 6 6 4 | 25E | 196 4 8 17 9 34 26 11 14 12 6 4 | 26 | 632 6 13 8 9 34 20 10 10 11 7 4 | 27E | 343 5 8 18 8 15 7 6 20 5 6 4 | 29 | 181 5 15 4 8 47 7 9 8 7 7 3 | 30 | 150 4 8 5 6 22 13 91 15 11 3 17 | 31 | 304 6 11 7 6 7 48 11 12 10 9 3 | ------|--------------------------------------------------| RMS | 323 6 11 17 8 40 95 19 12 12 11 | WRMS | 323 5 11 9 7 28 21 19 12 9 8 | MEDI | 200 5 11 9 7 24 24 8 11 9 7 | 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 3.1053.4 GPS week: 1053 Day: 4 MJD: 51619.0 CENT| CLK EPO | BRUS | WILL | ----|----------|----------------|----------------| emr | emr 2651 | 8 10 17 | 2 2 3 | esa | esa 2580 | 1 0 3 | 3 2 6 | gfz | gfz 2630 | 10 8 19 | 1 1 3 | igr | igr 2659 | 9 9 19 | 2 2 5 | jpl | jpl 2364 | 9 7 22 | 3 2 6 | usn | usn 2648 | 11 13 21 | 2 4 6 | 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 4.1053.4 GPS week: 1053 Day: 4 MJD: 51619.5 AC LOD AC LOD CENT FLAG | Xpole Ypole Xrt Yrt LOD | BIAS BIAS RMS ------------------------------------------------------------------------ cod uuuuu | 14 22 34 55 -20 | 5 14 emr* uuuuu | 71 26 -96 -56 -62 | -43 80 esa uuuuu | -18 -5 84 -96 24 | 19 30 gfz uuuuu | -20 -17 69 -6 -46 | 27 40 jpl uuuuu | -16 -61 -11 74 94 | 2 45 ngs uuuuu | -8 9 -194 -143 -56 | -31 74 sio xxxxx | -12 -19 11 -22 -109 | -21 62 usn uuuuu | -28 19 -4 34 57 | -3 29