Subject: [IGSREPORT-0835] IGS Final Orbit Comb(732)
From: Analysis Centres Coordinator / Geodetic Survey of Canada
Date: Thu, 10 Mar 1994 11:52:28 PST

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IGS Electronic Report    Thu Mar 10 11:52:28 PST 1994      Message Number 0835
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Author: Analysis Centres Coordinator / Geodetic Survey of Canada
Subject: IGS Final Orbit Comb(732)

IGS Final Orbit Combination Week 0732             (Jan 16, 1994 - Jan 22, 1994)

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

COMBINATION STRATEGY:

For a complete description of the combination strategy, see IGSMAIL #832.

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 IGS Final Orbit files generated and uploaded into CDDIS @ NASA/GSFC are:

 IGS07320-6.SP3  IGS GPS ephemeris files for days 0-6, week 0732 in SP3 format.
 IGS07327.ERP    Earth rotation parameters (ERP) associated with ephemerides.
 IGS07327.SUM    Complete report.

The old Rapid Service files have been renamed to:

 IGR07320-6.SP3  Rapid Service ephemeris files for days 0-6.
 IGR07327.ERP    Rapid Service earth rotation parameters (ERP).
 IGR07327.SUM    Rapid Service complete report.

REMARKS on IGS Final Orbit Combination:

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

2. ESA satellite clock corrections were not incuded in the combination since
   they exhibit systematic effects at the 10 nano-seconds level due to not
   accounting for relativistic effects.

3. The large clock correction RMS for COD on day 6 (Jan 22) is due to a delay
   in acknowledging a large (14 micro-sec.) clock reset on PRN 03 by broadcast
   message (ref NANU 028-94024). Since the COD clock solution is not included
   in the combination, the IGS clocks are not affected and are aligned to the
   EMR clocks. The resulting alignment to GPS time is better than what is shown
   i.e. an offset of -17.5 nanosec and a drift of -6.9 nanosec/day.

4. A maneuvre for PRN17 on days 4 and 5 (Jan 20-21) (ref NANU 003-94007). It
   was not included in combination on day 4 (Jan 20).

5. In the long arc analysis, state vector resets were modeled for PRN17 on
   day 5 (Jan 21) (maneuvre) and for PRN22 on day 3 (Jan 19).

ORBIT COMBINATION AND EVALUATION STATISTICS:

For a complete description of tables and statistics, see IGSMAIL #832.

Table 1: Week 0732 summary.                       (Jan 16, 1994 - Jan 22, 1994)

Table 1.0732.a   GPS week: 0732   MJD: 49368.0-49374.0

         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 |  .01  .01  .02  1.16   .19  -.09   .0   .11   .11 |     .2    -.8   74.6
    |  .00  .01  .01   .28   .69   .25   .1             |    1.4    2.1
emr |  .01 -.01 -.01  2.21   .62  -.19  -.3   .12   .12 | -294.0  -13.0     .9
    |  .01  .00  .00   .30   .48   .17   .1             |  305.3   19.8
esa |  .00  .00  .01  1.42   .12  -.86  -.1   .19   .17 |    1.6   -4.1   14.0
    |  .01  .01  .01   .26   .75   .63   .2             |   18.9    3.6
gfz | -.04  .00  .01  1.27  1.42  -.88  -.4   .13   .13 |   35.7  -11.2    9.4
    |  .01  .00  .01   .16   .51   .28   .1             |   35.2   28.1
jpl | -.01  .04  .00  1.15   .18  -.26   .2   .12   .13 |   35.8  -10.7     .9
    |  .01  .01  .01   .17   .55   .26   .1             |   35.9   30.3
ngs |  .02 -.05  .01  1.11  -.07   .39  2.0   .28   .27 |     .0     .0     .0
    |  .01  .02  .03   .40   .85   .26   .5             |     .0     .0
sio |  .02 -.05 -.05  2.11   .60  2.49   .4   .18   .18 |     .0     .0     .0
    |  .01  .01  .01   .20   .35  1.17   .1             |     .0     .0

Table 1.0732.b   GPS week : 0732   MJD: 49368.0-49374.0

         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  |   6   7   4   5   5   4   5 |
   2E |   7   8   8   9   8   9   9 |
   3  |   4   5   5   5   4   6   7 |
   4E |   7   7   5   7   6   6   7 |
   5E |   8   9   7  10   9   8   9 |
   7  |   5   6   5   6   5   4   6 |
   9  |   5   5   4   5   5   5   4 |
  12  |   5   4   5   5   4   4   4 |
  13  |   6   5   5   6   4   4   6 |
  14  |   5   5   4   4   4   5   4 |
  15E |   5   4   4   5   5   6   5 |
  16  |   6   7   5   7   7   5   6 |
  17E |   5   5   5   7 ---  10   6 | Maneuvre on days 4 and 5 (Jan 20-21).
  18  |   4   4   4   4   3   4   4 |
  19  |   4   4   4   6   5   5   5 |
  20E |   7   6   7   6   7   8   8 |
  21  |   5   5   4   5   5   4   6 |
  22E |   6   8   5   7   9   6   8 |
  23  |   7   5   7   4   6   7   6 |
  24E |   7   6   5   7   7   6 --- |
  25  |   7   6   6   7   6   5   7 |
  26  |   6   5   5   6   5   5   6 |
  27  |   4   4   4   6   5   5   5 |
  28  |   4   5   4   5   5   4   4 |
  29  |   4   4   4   4   4   4   4 |
  31  |   6   6   6   5   4   5   4 |

For tables 2 and 3, please refer to the complete report (IGS07327.SUM) posted
on CDDIS.