Subject: [IGSREPORT-1095] Wk 0755 IGS Rapid Orbits
From: AC Coordinator / NRCan GSDivision
Date: Sun, 17 Jul 1994 6:09:09 PDT

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IGS Electronic Report    Sun Jul 17  6:09:09 PDT 1994      Message Number 1095
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Author: AC Coordinator / NRCan GSDivision
Subject: Wk 0755 IGS Rapid Orbits

Rapid Service IGS Orbit Combination - Week 0755   (Jun 26, 1994 - Jul 02, 1994)

Contacts: F. Lahaye ([email-masked]), J. Kouba ([email-masked])

COMBINATION STRATEGY:

For a complete description of combination strategy, please refer to the report
posted on CDDIS (IGS07557.SUM).

SOFTWARE:

  The weighted average software used was developed by T. Springer and
G. Beutler during 1993. The GPS long arc orbit analysis software used here for
individual centre ephemeris evaluation was developed by Beutler et al. at the
Astronomical Institute of the University of Bern (AIUB). For more details on
the orbit combination and complete references for both software see:

   Beutler, Kouba, Springer, 1993, Combining orbits of the IGS processing
   centres, in IGS Analysis Centre Workshop, October 12-14, Ottawa, pp 19-55.

PRODUCTS GENERATED:

  The resulting average ephemeris and clocks are output to daily files in SP3
format. The satellite accuracy codes displayed in the header are based on the
weighted RMS for each satellite. Note that each file contains all the
satellites that appear in any of the centre ephemeris files. If a satellite or
centre was excluded from combination, a note in the REMARKS section of this
report will identify the exclusion and the reason.

  The Rapid Service Orbit files generated and uploaded into CDDIS @ NASA/GSFC
are:

 IGS07550-6.SP3  IGS GPS ephemeris files for days 0-6, week 0755 in SP3 format.
 IGS07557.ERP    Earth rotation parameters (ERP) associated with ephemerides.
 IGS07557.SUM    Complete report.

REMARKS on IGS Rapid Service Orbit Combination:

1. Starting with week 0730, the above satellite clock correction combination
   was put in place. The centres used in the combination are EMR, ESA, GFZ and
   JPL. The other centres are excluded because they either provide broadcast
   clocks (COD, NGS) or clock corrections are not provided (SIO). The clock
   information not used is still compared to combination for completeness.
   The value of 999999.999999 microseconds, according to the sp3 format 
   convention, is used to signify that no clock solution is available and
   therefore must not be used.

2. Only the GFZ "exact" clock corrections (one epoch out of two) are included
   in the combination and RMS computation (no "interpolation" values).

3. Starting with the GPS week 750 a new clock combination scheme was put in
   place. Now the clock solution alignments to the GPS time use only non-SA
   broadcast clock corrections (currently PRN 12, 15, 20) and the centre clock
   weights are determined from the fit RMS of this alignment. In this
   way the quality of the clock alignments (to the GPS time) is not affected
   by SA and more realistic and objective weights are determined and used in
   the clock combination, provided the non-SA satellites are representative of
   each centre clock solution quality.

4. PRN12 on day 3 (June 29) was excluded from the clock weights determination 
   since neither COD nor NGS submitted broadcast clock corrections on that day
   (also note that PRN12 was set unhealthy for the whole week).

5. The SIO orbit solutions for this week were excluded from combination due to
   their large rotations in Y-axis that were biasing the orientation of the
   combined orbits. Also the SIO solutions could not be processed through the
   long-arc process due to an incomplete pole file. Some other orbit solutions
   were excluded from combination because they were biasing the combined
   solution (as indicated by long-arc process), but they were kept in the orbit
   RMS computation. The following table lists the exclusions:

                  Day (Date)  |  PRN    | Centres
                 -------------+---------+--------
                  2 (June 28) | 4,9     |   NGS  
                  2 (June 28) | 9       |   EMR  
                  3 (June 29) | 9       |   NGS  

6. Some clock solutions were excluded from combination because they were
   biasing the combined clock solution (as indicated by clock comparisons),
   but they were kept in the clock RMS computation. The following table
   lists the exclusions (note that JPL did not provide any clock corrections
   for PRN 12 and 15 on days 1-6 (June 27-July 02)):

                  Day (Date)  |  PRN   | Centres
                 -------------+--------+--------
                  4 (June 30) |  ALL   |   JPL  
                  5 (July 01) |  ALL   |   JPL  
                  6 (July 02) |  ALL   |   JPL  

7. State vector resets were modeled for the following satellite to alleviate 
   the effects of modelling problems, experienced by all centres, in the
   long arc process.

                  Day (Date)  |   TIME   |  PRN  | Centres  
                 -------------+----------+-------+--------
                  4 (June 30) | 00:00:00 | 05,12 |  ALL
                  6 (July 01) | 00:00:00 | 23    |  ALL

8. UT values from Bulletin A were used in the long arc evaluation for JPL due 
   to discontinuities found in its UT series (day 1/Jun 27).

ORBIT COMBINATION AND EVALUATION STATISTICS:

For a complete description of tables and statistics, please refer to the report
posted on CDDIS (IGS07557.SUM).

Table 1: Week 0755 summary.                       (Jun 26, 1994 - Jul 02, 1994)

Table 1.0755.a   GPS week: 0755   MJD: 49529.0-49535.0

         Mean and standard deviations of transformation parameters.
         WRMS - orbit RMS weighted by the SP3 header accuracy codes.
         Units: meters, mas, ppb, nano-sec, nano-sec/day.

CENT|   DX   DY   DZ    RX    RY    RZ  SCL   RMS  WRMS |   TOFT  TDRFT    RMS
----|---------------------------------------------------|---------------------
cod |  .00  .01  .01  -.31  -.22   .10  -.1   .13   .12 |   -2.3    3.5  262.7
    |  .01  .01  .01   .41   .19   .29   .1             |    7.3   12.3
emr |  .01  .00  .00  -.23  -.17   .22   .0   .24   .18 | -529.3  -31.5    5.4
    |  .01  .01  .01   .50   .53   .25   .3             |   55.4   19.1
esa |  .01 -.01  .02   .16  -.33  -.36   .0   .22   .20 |   -2.2   -2.4   11.1
    |  .01  .01  .02   .29   .65   .38   .1             |    9.9   22.2
gfz | -.03  .00 -.01 -1.07  -.52  -.30  -.1   .14   .12 | -525.6  -26.8   11.5
    |  .01  .01  .00   .18   .19   .23   .2             |   55.1   22.2
jpl |  .02 -.01  .02   .21  -.53   .17  -.1   .33   .31 | -524.5  -32.1    5.7
    |  .02  .02  .01   .63   .36   .38   .2             |   55.7   19.7
ngs |  .01 -.03 -.03  -.42  -.48   .02   .8   .67   .72 |  351.6 -540.3 5000.9
    |  .04  .03  .07   .76   .67  1.01   .4             |  938.1 1448.5
sio | -.01 -.03  .10 -1.07  5.85   .98   .2   .37   .36 |     .0     .0     .0
    |  .02  .02  .04   .59  1.06   .31   .4             |     .0     .0

Table 1.0755.b   GPS week : 0755   MJD: 49529.0-49535.0

         Satellite position sigmas for the combined orbits
         (coded in the IGS SP3 orbit files).
         "E" flags eclipsing satellites.
         Units: cm.

              Day of GPS week
 PRN  |   0   1   2   3   4   5   6 |  Remarks
------|-----------------------------|------------------------------------------
   1  |   9   8   9   6   8   7   6 |
   2E |   6   7   8   7   8  11   5 |
   4E |  12  12  14  11  17  19  10 |
   5E |   7   9   8   7  16   7   8 |
   6  |   4   6   6   5   7   6   4 |
   7  |   7  12  10   9   9  10   9 |
   9  |   6  11  10  10   8   5   5 |
  12E |  13  30  43  33  27   5   6 |
  14  |   6   6   6   7   6   9   5 |
  15E |  11  11  15   9   8   8  11 |
  16  |   4   9   9   8  10   6  10 |
  17E |  10   9  11  11  13   9   8 |
  18  |  14   4   8   6   7   6   4 |
  19  |   5   5   7   6   7   5   4 |
  20E |   8   6   7   6  11   5   6 |
  21  |  16   8   8   9   9   6   8 |
  22E |   9   7   8   7  12  13  12 |
  23  |   8   9   8   7  12  12   9 |
  24E |   9  11  12  12  15  14  10 |
  25  |  10   7   8   9  11   8   7 |
  26  |   5  10  11  12   9   5   6 |
  27  |   4   7   7   6   6   5   4 |
  28  |   6   5   7   5   5   7   5 |
  29  |   6   6   8   5   6   4   4 |
  31  |   6   7   9   7   6   5   5 |

Table 2: Daily transformation of each centre to the combined IGS orbit and
         clocks for each day of the week. The transformation displayed is the
         sum of a priori and estimated transformations.
         WRMS - RMS weighted by the centres SP3 header accuracy codes.
         Units: meters, mas, ppb, nano-sec, nano-sec/day.

Table 2.0755.0   GPS week: 0755   Day: 0   MJD: 49529.0

CENT|   DX   DY   DZ    RX    RY    RZ  SCL   RMS  WRMS |   TOFT  TDRFT    RMS
----|---------------------------------------------------|---------------------
cod |  .00  .00  .01  -.09  -.28   .49   .1   .12   .12 |   -4.3   13.9   78.3
emr |  .03 -.01 -.02  -.57  -.12   .31  -.3   .14   .14 | -453.2  -18.3    2.3
esa |  .00  .00  .03  -.08  -.01  -.22  -.1   .21   .21 |    4.1  -21.1    3.0
gfz | -.03  .00 -.01 -1.06  -.59  -.35  -.2   .11   .10 | -449.9  -10.0   11.8
jpl |  .00  .01  .02   .25 -1.30  -.60  -.2   .38   .33 | -448.0  -19.9    7.3
ngs |  .00 -.02  .01  -.62  -.78   .33   .2   .42   .32 |   -3.5   14.0   76.6
sio |  .00 -.07  .12  -.50  4.11   .81  -.2   .71   .71 |     .0     .0     .0

Table 2.0755.1   GPS week: 0755   Day: 1   MJD: 49530.0

CENT|   DX   DY   DZ    RX    RY    RZ  SCL   RMS  WRMS |   TOFT  TDRFT    RMS
----|---------------------------------------------------|---------------------
cod |  .01  .01  .01   .22  -.27   .45   .0   .13   .13 |   -6.6    6.7   79.1
emr |  .01  .02 -.01   .80  -.51  -.23   .2   .24   .22 | -482.3  -38.6    2.7
esa |  .01 -.01  .00   .65  -.81  -.06   .1   .23   .19 |  -21.6  -21.2    2.8
gfz | -.03  .01 -.02  -.90  -.82  -.40  -.3   .12   .10 | -478.4  -32.1   12.6
jpl |  .01 -.04  .03   .27  -.36  -.04   .1   .21   .21 | -477.4  -40.0    3.5
ngs |  .01 -.08  .07  -.18 -1.43  -.62   .3   .48   .50 | 2479.0-3825.013230.0
sio | -.03 -.03  .13  -.70  5.55  1.60   .5   .33   .32 |     .0     .0     .0

Table 2.0755.2   GPS week: 0755   Day: 2   MJD: 49531.0

CENT|   DX   DY   DZ    RX    RY    RZ  SCL   RMS  WRMS |   TOFT  TDRFT    RMS
----|---------------------------------------------------|---------------------
cod |  .00  .01  .00  -.03   .11  -.12  -.2   .12   .10 |    4.7    4.3  668.1
emr |  .02  .02 -.01  -.31   .81   .28   .5   .47   .25 | -505.2   -7.4   10.5
esa |  .01 -.01  .02   .20  -.12  -.48   .3   .21   .18 |    6.8   30.0   27.0
gfz | -.02 -.01 -.02 -1.31  -.36   .09  -.4   .16   .14 | -504.4    2.3   11.0
jpl |  .04 -.02  .00   .83  -.41   .51  -.2   .33   .33 | -500.5   -7.3    1.9
ngs | -.03  .00 -.09   .41  -.86 -1.73  1.1  1.38  1.59 |   -1.6   24.5   77.6
sio | -.03 -.01  .04  -.70  5.72   .94   .7   .24   .22 |     .0     .0     .0

Table 2.0755.3   GPS week: 0755   Day: 3   MJD: 49532.0

CENT|   DX   DY   DZ    RX    RY    RZ  SCL   RMS  WRMS |   TOFT  TDRFT    RMS
----|---------------------------------------------------|---------------------
cod |  .01  .00  .03  -.44  -.26  -.06  -.3   .10   .09 |    6.9  -13.6   77.8
emr |  .00 -.01 -.01  -.10  -.17   .09   .1   .20   .18 | -515.6  -64.0    3.0
esa |  .02 -.01  .01   .46  -.32  -.62  -.1   .21   .17 |    -.4  -29.2    4.8
gfz | -.03 -.01  .00 -1.25  -.55  -.12  -.2   .14   .12 | -511.3  -58.8   12.2
jpl |  .04 -.01  .01   .23  -.48   .31  -.1   .29   .29 | -510.3  -65.8    2.9
ngs | -.03 -.02 -.15   .56  -.44  1.33  1.1   .56   .56 |     .0     .0     .0
sio |  .00 -.03  .10 -1.30  6.18   .89   .6   .25   .21 |     .0     .0     .0

Table 2.0755.4   GPS week: 0755   Day: 4   MJD: 49533.0

CENT|   DX   DY   DZ    RX    RY    RZ  SCL   RMS  WRMS |   TOFT  TDRFT    RMS
----|---------------------------------------------------|---------------------
cod |  .01  .02  .01  -.60  -.51   .16   .1   .16   .14 |     .0  -12.2   78.9
emr |  .00  .00  .01  -.27  -.94   .54  -.2   .18   .18 | -556.7  -37.8    7.3
esa |  .01  .00  .00   .01 -1.52  -.98   .1   .25   .22 |   -8.7    3.0    8.1
gfz | -.05  .00 -.01 -1.13  -.66  -.53  -.1   .19   .16 | -549.1  -38.5    6.8
jpl |  .02 -.04  .02 -1.07  -.57   .24  -.3   .38   .38 | -552.2  -36.6    8.3
ngs |  .09  .00 -.05 -1.66  -.56   .87  1.2   .49   .46 |     .9  -10.2   77.4
sio |  .00  .00  .13 -1.10  6.22   .88  -.1   .25   .23 |     .0     .0     .0

Table 2.0755.5   GPS week: 0755   Day: 5   MJD: 49534.0

CENT|   DX   DY   DZ    RX    RY    RZ  SCL   RMS  WRMS |   TOFT  TDRFT    RMS
----|---------------------------------------------------|---------------------
cod |  .00  .00 -.01 -1.00  -.23  -.26   .0   .17   .12 |  -15.0   19.2   78.6
emr |  .02  .00  .00  -.79  -.07   .17  -.1   .12   .12 | -595.3  -16.0    3.6
esa |  .02 -.01  .04  -.14   .41   .15   .2   .23   .23 |    -.6    3.9    4.1
gfz | -.04  .01 -.01 -1.02  -.33  -.55   .0   .15   .14 | -593.1   -7.4   12.8
jpl |  .03  .00  .01   .13  -.40   .38   .1   .33   .29 | -590.9  -15.2    6.9
ngs |  .02 -.04  .01  -.62   .05   .19   .7   .36   .29 |  -11.5   12.4   77.0

Table 2.0755.6   GPS week: 0755   Day: 6   MJD: 49535.0

CENT|   DX   DY   DZ    RX    RY    RZ  SCL   RMS  WRMS |   TOFT  TDRFT    RMS
----|---------------------------------------------------|---------------------
cod |  .00  .01  .00  -.25  -.12   .01  -.1   .12   .11 |   -2.1    6.1   77.5
emr |  .02  .00  .00  -.36  -.20   .42  -.2   .10   .10 | -596.5  -38.4    2.0
esa |  .03 -.01  .03   .02   .10  -.28  -.1   .19   .16 |    4.6   18.1    1.8
gfz | -.05  .00 -.01  -.80  -.32  -.28   .1   .12   .10 | -592.7  -43.0   12.3
jpl |  .04  .01  .01   .82  -.15   .36   .0   .35   .33 | -592.0  -39.7    5.4
ngs |  .05 -.04 -.03  -.80   .64  -.27  1.0   .36   .35 |   -1.7    2.2   75.9
sio | -.03 -.04  .05 -2.10  7.33   .76  -.1   .20   .20 |     .0     .0     .0

For Tables 3.0755.0-6, please refer to the complete report (IGS07557.SUM)
posted on CDDIS.

[Mailed From: Francois Lahaye <[email-masked]>]