[IGSREPORT-10177] Wk 1212 IGS SINEX Combination
David Hutchison
hutch at geod.nrcan.gc.ca
Thu Apr 17 21:28:11 PDT 2003
******************************************************************************
IGS Electronic Report 17 Apr 21:28:14 PDT 2003 Message Number 10177
******************************************************************************
Author: R. Ferland , D. Hutchison
===================================================================
Combined AC solution for GPS week 1212 - 03/03/30 to 03/04/05
===================================================================
1) Contacts:
============
e-mail: ferland at geod.nrcan.gc.ca
Tel: (613)995-4002 (Remi Ferland)
Fax: (613)995-3215
2) Products:
============
All products are available at cddisa.gsfc.nasa.gov
igs03P1212.snx Combined weekly solution.
igs03P1212.erp Daily Earth Rotation Parameters.
igs00p02.erp Daily Earth Rotation Parameters since GPS week 1013.
IGS03P14.snx Cumulative Combined solution.
igs03P1212.sum This file.
igs03P1212.itr Residuals between the AC and the IGS00 for the RF stations.
igs03P1212.res Residuals between the AC and the Combined Weekly solution.
IGS03P14.res Residuals between the AC and the Cumulative Combined solution.
Where IGSyyPww & igsyyPwwww represent:
yy Last 2 digits of the year
ww week in year yy
wwww GPS week
P GPS technique used
3) Combination Strategy:
========================
The AC solutions are processed using the following procedure:
3-1) The AC solutions are checked/corrected for possible format problems,
station names inconsistencies, etc...
3-2) The AC solutions are unconstrained according to the information provided
in the SOLUTION/APRIORI Block.
3-3) The AC solutions are aligned (using a 7-parameters) and compared to the
IGS00 stations at the current epoch.
ftp://igscb.jpl.nasa.gov/igscb/station/coord/IGS01P37_RS54.SNX.Z
3-4) The AC are compared to IGS00, to each other, to the previous week
solution and to the cumulative solution in order to identify and remove
outliers.
3-5) The weekly AC solutions are combined and added to the cumulative
combined solution. The cumulative combination is done to ensures 14
parameters singularity.
The weekly combined solution is aligned to the IGS00 of the current
epoch using a 7-parameters transformation. The singular cumulative
combined solution is aligned to the IGS00 of the reference epoch
using a 14-parameters transformation and the 54 ITRF station positions
and velocities. The IGS00 is a realization of ITRF2000.
For more details, see:
Blewitt, G., C. Boucher and J. Kouba, 1997, Procedure for ITRF continuous
realization, the report of the IGS GB, presented to the IGS Governing
Board Meeting held in San Francisco, Dec. 11.
Kouba, J., J. Ray and M.M. Watkins, IGS Reference Frame Realization, 1998
IGS Analysis Center Workshop Proceedings, European Space Operations
Centre, Darmstadt, Germany.
The combination software was developed at NRCan.
4) Remarks:
===========
ITR = IGS01P37_RS54.SNX
igs = igs03P1212.snx ( Weekly Combination )
IGS = IGS03P14.snx ( Cumulative Solution )
BuA = IERS Bulletin A
mit ncl are used to quality control the weekly combination.
gfz excluded from the geocenter estimation (Sec. 5-4).
Solutions with manual station deletion:
After unconstraining:
esa EISL PIMO
gfz BAHR
jpl IISC KELY SANT
ngs KOKB
ncl QAQ1
New stations in the cumulative solution IGS03P14.snx
GLPS A ----
4-1) Starting with GPS week 1143, the solutions are aligned to the
IGS01P37_RS54.SNX realization of ITRF2000.
4-2) Starting with GPS week 1078, UT1-UTC from IERS Bulletin A
is included in the erp files.
5) Results:
===========
5-1) AC (Variance Factor)^0.5 estimates:
==================================================
The residuals used in the estimation of the Variance Factor
are the differences between the cumulative combined solution
and each AC weekly solution.
SF = (Variance Factor)^0.5 = (Chi^2/dof)^0.5
Final(SF) = Apriori(SF) * Aposteriori(SF)
Solution |# sta| #RF | Apriori(SF)|Aposteriori(SF)| Final(SF)|
---------------|-----|-----|---------------|---------------|---------------|
cod | 155 | 45 | 20.303 | 1.002 | 20.349 |
emr | 42 | 21 | 4.751 | 1.002 | 4.759 |
esa | 56 | 37 | 12.252 | 1.001 | 12.259 |
gfz | 176 | 44 | 8.166 | 1.002 | 8.183 |
jpl | 89 | 26 | 4.394 | 1.002 | 4.403 |
ngs | 70 | 46 | 21.671 | 1.001 | 21.683 |
sio | 145 | 47 | 1.966 | 1.001 | 1.969 |
mit | 213 | 45 | 1.692 | 0.901 | 1.525 |
ncl | 138 | 47 | 1.285 | 0.992 | 1.275 |
igs | 199 | 47 | 1.300 | 0.999 | 1.298 |
---------------|-----|-----|---------------|---------------|---------------|
5-2) Solution Residuals weighted Average & STD :
=====================================================
5-2-1) With respect to the IGS00 stations:
=============================================
Solution | Weighted Average (mm) | STD (mm) |
| N E U | N E U |
---------------|---------------------------|---------------------------|
cod 44 | 1.1 0.5 -0.5 | 3.0 3.8 10.0 |
emr 20 | -0.4 -0.1 0.2 | 4.0 2.9 10.1 |
esa 35 | -2.8 0.1 1.3 | 5.9 3.9 13.8 |
gfz 43 | 1.4 0.5 0.4 | 3.0 3.7 9.2 |
jpl 25 | 1.6 0.4 0.5 | 2.6 2.9 13.3 |
ngs 44 | -1.9 0.3 0.5 | 8.0 10.3 14.6 |
sio 46 | 0.4 0.9 0.2 | 3.8 5.0 7.6 |
mit 44 | 0.2 0.5 0.5 | 3.3 3.4 8.6 |
ncl 46 | 0.4 0.3 0.4 | 3.0 3.3 6.1 |
---------------|---------------------------|---------------------------|
5-2-2) With respect to the Weekly Combination:
=================================================
Solution | Weighted Average (mm) | STD (mm) |
| N E U | N E U |
---------------|---------------------------|---------------------------|
cod 150 | 0.6 0.2 0.2 | 1.4 1.2 5.1 |
emr 42 | -1.3 -0.4 -1.8 | 2.1 2.1 7.8 |
esa 55 | -3.8 -0.2 0.9 | 4.5 3.1 10.7 |
gfz 169 | 0.4 -0.4 -0.2 | 1.4 1.6 5.5 |
jpl 87 | 0.7 0.4 -0.7 | 1.7 1.6 8.5 |
ngs 68 | -1.8 -0.8 -0.8 | 7.4 9.2 14.2 |
sio 135 | -0.1 0.1 0.4 | 2.5 2.6 5.0 |
mit 193 | -0.7 -0.1 -0.2 | 1.0 0.7 3.5 |
ncl 134 | -0.4 -0.1 0.9 | 0.8 0.6 2.9 |
ITR 46 | -0.7 -0.7 -0.1 | 3.1 3.2 8.3 |
---------------|---------------------------|---------------------------|
5-2-3) With respect to the Cumulative Combination:
=====================================================
Solution | Weighted Average (mm) | STD (mm) |
| N E U | N E U |
---------------|---------------------------|---------------------------|
cod 137 | 0.8 0.2 -0.4 | 2.4 2.1 7.6 |
emr 39 | -1.1 -0.4 -2.4 | 2.6 2.6 9.9 |
esa 55 | -3.5 -0.2 0.8 | 5.6 3.1 12.2 |
gfz 139 | 0.7 -0.5 -0.6 | 2.5 2.6 7.5 |
jpl 73 | 0.8 0.3 -1.0 | 1.9 2.1 11.1 |
ngs 68 | -1.7 -1.0 -0.6 | 7.6 9.7 14.8 |
sio 125 | 0.1 0.2 0.1 | 3.5 3.6 6.7 |
mit 154 | -0.5 -0.1 -0.3 | 2.4 2.1 6.0 |
ncl 126 | -0.2 -0.2 0.6 | 2.2 1.8 5.1 |
igs 157 | 0.1 0.0 -0.4 | 1.8 1.7 5.6 |
ITR 54 | -0.3 -0.6 0.1 | 1.7 1.9 3.7 |
---------------|---------------------------|---------------------------|
5-3) 7-Parameters Transformation: AC ----> IGS01P37_RS54.snx
=================================================================
5-3-1) Estimates :
=====================
Solution | R X R Y R Z T X T Y T Z SCL |
| (mas) (mas) (mas) (mm) (mm) (mm) (ppb) |
---------------|---------------------------------------------------------------|
cod | -0.002 0.001 -0.007 10.2 9.2 -2.5 1.63 |
emr | -0.001 -0.013 -0.012 -13.4 1.1 5.9 1.18 |
esa | 0.160 0.007 -0.010 -17.5 24.4 2.9 0.58 |
gfz | 0.016 -0.035 0.072 -1.6 0.8 -0.7 1.05 |
jpl | 0.016 0.025 -0.025 5.0 7.0 14.9 0.70 |
ngs | -0.001 -0.176 -0.032 -1.7 3.9 -31.0 0.58 |
sio | -0.054 0.011 -0.036 6.1 -3.0 40.2 1.24 |
mit | 0.006 -0.007 -0.008 1.1 -0.2 0.4 1.15 |
ncl | -0.026 -0.032 -0.031 0.4 -0.4 -1.8 1.01 |
---------------|---------------------------------------------------------------|
5-3-2) STD :
===============
Solution | R X R Y R Z T X T Y T Z SCL |
| (mas) (mas) (mas) (mm) (mm) (mm) (ppb) |
---------------|---------------------------------------------------------------|
cod | 0.058 0.061 0.066 1.5 1.5 1.5 0.24 |
emr | 0.086 0.086 0.104 2.3 2.3 2.3 0.36 |
esa | 0.070 0.074 0.075 1.9 1.8 1.8 0.28 |
gfz | 0.059 0.061 0.068 1.6 1.6 1.6 0.24 |
jpl | 0.081 0.081 0.090 2.1 2.1 2.1 0.32 |
ngs | 0.059 0.061 0.068 1.6 1.6 1.6 0.24 |
sio | 0.057 0.060 0.066 1.5 1.5 1.5 0.24 |
mit | 0.058 0.061 0.068 1.5 1.5 1.5 0.24 |
ncl | 0.057 0.060 0.066 1.5 1.5 1.5 0.24 |
---------------|---------------------------------------------------------------|
5-4) Geocenter:
====================
| X Y Z | s X s Y s Z |
| (mm) (mm) (mm) | (mm) (mm) (mm) |
---------------|---------------------------|---------------------------|
igs | 9.0 4.4 5.5 | 2.1 1.8 3.9 |
---------------|---------------------------|---------------------------|
5-5) ERP Residuals Weighted Average & STD :
================================================
5-5-1) Weighted Average :
============================
Solution | UT LOD XPO XPOR YPO YPOR |
| us us .01mas .01ma/d .01mas .01ma/d |
---------------|------------------------------------------------------------|
cod | --- 16.1 .4 --- -4.9 --- |
emr | --- 9.2 -1.0 1.1 -2.4 14.1 |
esa | --- 20.5 -11.8 --- -14.6 --- |
gfz | --- 13.0 -3.9 -2.8 9.0 -1.3 |
jpl | --- -51.0 3.3 -10.6 -4.3 8.5 |
ngs | --- 16.0 30.2 40.6 14.9 -25.2 |
sio | --- -34.9 -2.8 1.3 .8 -1.2 |
mit | --- 22.5 -.1 3.1 -5.8 5.6 |
ncl | --- 14.2 -3.3 --- 2.7 --- |
ITR | --- --- --- --- --- --- |
BuA | --- 27.0 -10.1 4.1 21.4 5.2 |
---------------|------------------------------------------------------------|
5-5-2) STD :
===============
Solution | UT LOD XPO XPOR YPO YPOR |
| us us .01mas .01ma/d .01mas .01ma/d |
---------------|------------------------------------------------------------|
cod | --- 8.5 1.7 --- 1.6 --- |
emr | --- 18.7 5.8 10.0 3.4 20.4 |
esa | --- 11.5 3.8 --- 5.5 --- |
gfz | --- 9.9 2.6 10.2 2.2 5.3 |
jpl | --- 62.6 2.4 8.6 2.3 8.7 |
ngs | --- 37.4 9.2 24.8 7.0 49.1 |
sio | --- 18.2 3.3 5.1 2.1 13.7 |
mit | --- 3.1 1.4 6.7 .7 9.6 |
ncl | --- 2.4 2.3 --- 1.3 --- |
ITR | --- --- --- --- --- --- |
BuA | --- 21.0 6.7 6.3 8.0 20.3 |
---------------|------------------------------------------------------------|
5-6) Outliers:
===================
Thresholds set at 5 sigmas and 50 mm.
Solution Solution | Station | N E U |
Minus |code id soln| (mm) (mm) (mm)|
-----------------------------------------|------------|-----------------------|
| | |
IGS01P37_RS54.snx esa12127.snx |SANT A ----| 4.9 7.2 54.7|
| | |
IGS01P37_RS54.snx jpl12127.snx |MAC1 A ----| -5.0 2.5 41.7|
IGS01P37_RS54.snx jpl12127.snx |YAR1 A ----| 0.0 3.7 -55.4|
| | |
cod12127.snx ngs12127.snx |EISL A ----| -13.6 -51.5 7.6|
| | |
esa12127.snx ngs12127.snx |RIOG A ----| -50.2 -4.4 -7.1|
| | |
jpl12127.snx ngs12127.snx |EISL A ----| -8.7 -50.3 23.8|
jpl12127.snx ngs12127.snx |STJO A ----| -1.6 -4.6 -54.8|
jpl12127.snx ngs12127.snx |WUHN A 2| 3.6 -4.8 63.5|
| | |
jpl12127.snx sio12127.snx |STJO A ----| -1.8 -3.4 -45.7|
jpl12127.snx sio12127.snx |WUHN A 2| 5.0 -6.6 57.1|
| | |
jpl12127.snx ncl1212g.snx |STJO A ----| -1.1 -0.4 -38.8|
| | |
IGS03P13.snx cod12127.snx |RESO A ----| 1.8 -13.8 1.3|
| | |
IGS03P13.snx gfz12127.snx |KELY A ----| 1.2 4.9 54.5|
IGS03P13.snx gfz12127.snx |PRDS A ----| 20.0 -0.4 -5.4|
IGS03P13.snx gfz12127.snx |RESO A ----| 5.2 -11.2 4.4|
| | |
IGS03P13.snx ngs12127.snx |THTI A ----| -0.4 3.6 51.5|
| | |
IGS03P13.snx mit1212g.snx |PRDS A ----| 14.9 -1.0 -12.0|
| | |
IGS03P13.snx ncl1212g.snx |KELY A ----| -1.4 4.7 48.3|
IGS03P13.snx ncl1212g.snx |RESO A ----| 1.7 -12.6 3.0|
| | |
IGS03P13.snx igs03P1212.snx |KODK A ----| 1.8 -7.7 8.2|
IGS03P13.snx igs03P1212.snx |KOSG A ----| 8.6 2.5 3.1|
IGS03P13.snx igs03P1212.snx |PRDS A ----| 15.7 0.2 -10.3|
IGS03P13.snx igs03P1212.snx |WHIT A ----| -0.6 -7.2 -3.8|
-----------------------------------------|------------|-----------------------|
5-7) Conflicts:
===========================
5-7-1) Station Name Conflicts:
=============================
IERS DOMES NO cod emr esa gfz jpl ngs sio IGS igs
============= ====== ====== ====== ====== ====== ====== ====== ====== ======
42202M005 AREQ A AREQ A AREQ A AREQ A AREQ B AREQ A AREQ A
40405S031 GOLD A GOLD A GOLD A GOL2 A GOL2 A GOLD A GOLD A
22306M002 IISC A IISC A IISC B IISC A IISC A IISC B IISC A IISC A IISC A
13407S012 MADR A MADR A MAD2 A MAD2 A MADR A MADR A
30314M002 SUTH A SUTH B SUTH A SUTH A SUTH A SUTH A SUTH A
43001M002 THU3 A THU3 A THU3 A THU2 A THU2 A
THU3 A THU3 A
50103M108 TIDB A TIDB A TIDB A TIDB A TID2 A TIDB A TIDB A TIDB A
TID1 A TID2 A
TID2 A
50107M004 YAR2 A YAR2 A YAR2 A YAR1 A YAR1 A
12361M001 KHAJ A KHAJ A KHAJ A
MISSING IERS DOMES NOS AT gfz:
-----------------------------
BISH A PMON A PALM A
MISSING IERS DOMES NOS AT sio:
-----------------------------
CAVA A SFEL A VOLT A BRAS A
IERS DOMES NO mit ncl IGS igs
============= ====== ====== ====== ======
13407S012 MADR A MADR A MADR A
MAD2 A
43001M002 THU3 A THU3 A THU2 A
THU2 A THU3 A
40405S031 GOLD A GOLD A GOLD A GOLD A
GOL2 A
50103M108 TIDB A TID2 A TIDB A TIDB A
TID1 A TIDB A
TID2 A
50107M004 YAR2 A YAR2 A YAR1 A YAR1 A
10002M006 GRAS A GRAS A GRAS A GRAS A
MISSING IERS DOMES NOS AT mit:
-----------------------------
PALM A PMON A BISH A CAVA A SFEL A VOLT A BRAS A
5-7-2) Station Antenna Conflicts:
================================
_______________________
|Enforcing these aliases|
|_______________________|
YAR1 A: YAR2 A
IISC A: IISC B
SUTH A: SUTH B
MADR A: MAD2 A
AREQ A: AREQ B
GOLD A: GOL2 A
ABBREVIATIONS:
-------------
L1: L1 Offset
L2: L2 Offset
ECC: Eccentricity
-N: NORTH (Latitude)
-E: EAST (Longitude)
-U: UP (Vertical)
Compare to file IGS.SNX (IGS).
Antenna Conflicts in file cod12127.snx (cod).
------- --------- -- ----
STN L1-U L1-N L1-E L2-U L2-N L2-E ECC-U ECC-N ECC-E
AGY CODE PT (M.) (M.) (M.) (M.) (M.) (M.) (M.) (M.) (M.)
=== ==== == ==== ==== ==== ==== ==== ==== ==== ==== ====
cod OHI2 A .1100 .0000 .0000 .1280 .0000 .0000 .0008 .0000 .0000
IGS OHI2 A .1100 .0000 .0000 .1280 .0000 .0000 -.0080 .0000 .0000
cod WUHN A .1100 .0000 .0000 .1280 .0000 .0000 2.3200 .0000 .0000
IGS WUHN A .1100 .0000 .0000 .1280 .0000 .0000 2.3610 -.0094 -.0022
Antenna Conflicts in file esa12127.snx (esa).
------- --------- -- ----
STN L1-U L1-N L1-E L2-U L2-N L2-E ECC-U ECC-N ECC-E
AGY CODE PT (M.) (M.) (M.) (M.) (M.) (M.) (M.) (M.) (M.)
=== ==== == ==== ==== ==== ==== ==== ==== ==== ==== ====
esa KIRU A .1081 .0003 -.0002 .1256 .0009 .0005 .0620 .0000 .0000
IGS KIRU A .1100 .0000 .0000 .1280 .0000 .0000 .0620 .0000 .0000
esa NYAL A .0780 .0000 .0000 .0960 .0000 .0000 5.2160 .0000 .0000
IGS NYAL A .0780 .0000 .0000 .0960 .0000 .0000 5.2160 .0040 -.0010
Antenna Conflicts in file gfz12127.snx (gfz).
------- --------- -- ----
STN L1-U L1-N L1-E L2-U L2-N L2-E ECC-U ECC-N ECC-E
AGY CODE PT (M.) (M.) (M.) (M.) (M.) (M.) (M.) (M.) (M.)
=== ==== == ==== ==== ==== ==== ==== ==== ==== ==== ====
gfz NYAL A .0780 .0000 .0000 .0960 .0000 .0000 5.2160 .0000 .0000
IGS NYAL A .0780 .0000 .0000 .0960 .0000 .0000 5.2160 .0040 -.0010
Antenna Conflicts in file jpl12127.snx (jpl).
------- --------- -- ----
STN L1-U L1-N L1-E L2-U L2-N L2-E ECC-U ECC-N ECC-E
AGY CODE PT (M.) (M.) (M.) (M.) (M.) (M.) (M.) (M.) (M.)
=== ==== == ==== ==== ==== ==== ==== ==== ==== ==== ====
jpl NYAL A .0780 .0000 .0000 .0960 .0000 .0000 5.2160 .0000 .0000
IGS NYAL A .0780 .0000 .0000 .0960 .0000 .0000 5.2160 .0040 -.0010
jpl WUHN A .1100 .0000 .0000 .1280 .0000 .0000 2.3610 .0000 .0000
IGS WUHN A .1100 .0000 .0000 .1280 .0000 .0000 2.3610 -.0094 -.0022
Antenna Conflicts in file mit1212g.snx (mit).
------- --------- -- ----
STN L1-U L1-N L1-E L2-U L2-N L2-E ECC-U ECC-N ECC-E
AGY CODE PT (M.) (M.) (M.) (M.) (M.) (M.) (M.) (M.) (M.)
=== ==== == ==== ==== ==== ==== ==== ==== ==== ==== ====
mit NYAL A .0780 .0000 .0000 .0960 .0000 .0000 5.2160 .0000 .0000
IGS NYAL A .0780 .0000 .0000 .0960 .0000 .0000 5.2160 .0040 -.0010
mit WUHN A .1100 .0000 .0000 .1280 .0000 .0000 2.3610 .0000 .0000
IGS WUHN A .1100 .0000 .0000 .1280 .0000 .0000 2.3610 -.0094 -.0022
Antenna Conflicts in file ncl1212g.snx (ncl).
------- --------- -- ----
STN L1-U L1-N L1-E L2-U L2-N L2-E ECC-U ECC-N ECC-E
AGY CODE PT (M.) (M.) (M.) (M.) (M.) (M.) (M.) (M.) (M.)
=== ==== == ==== ==== ==== ==== ==== ==== ==== ==== ====
ncl NYAL A .0780 .0000 .0000 .0960 .0000 .0000 5.2160 .0000 .0000
IGS NYAL A .0780 .0000 .0000 .0960 .0000 .0000 5.2160 .0040 -.0010
ncl WUHN A .1100 .0000 .0000 .1280 .0000 .0000 2.3610 .0000 .0000
IGS WUHN A .1100 .0000 .0000 .1280 .0000 .0000 2.3610 -.0094 -.0022
Antenna Conflicts in file ngs12127.snx (ngs).
------- --------- -- ----
STN L1-U L1-N L1-E L2-U L2-N L2-E ECC-U ECC-N ECC-E
AGY CODE PT (M.) (M.) (M.) (M.) (M.) (M.) (M.) (M.) (M.)
=== ==== == ==== ==== ==== ==== ==== ==== ==== ==== ====
ngs BAKO A .0757 .0000 .0000 .0745 .0000 .0000 1.6160 .0000 .0000
IGS BAKO A .0780 .0000 -.0030 .0744 -.0031 -.0013 1.6160 .0000 .0000
ngs NYAL A .0780 .0000 .0000 .0960 .0000 .0000 5.2160 .0000 .0000
IGS NYAL A .0780 .0000 .0000 .0960 .0000 .0000 5.2160 .0040 -.0010
ngs WUHN A .1081 .0000 .0000 .1256 .0000 .0000 2.3610 -.0094 -.0022
IGS WUHN A .1100 .0000 .0000 .1280 .0000 .0000 2.3610 -.0094 -.0022
Antenna Conflicts in file sio12127.snx (sio).
------- --------- -- ----
STN L1-U L1-N L1-E L2-U L2-N L2-E ECC-U ECC-N ECC-E
AGY CODE PT (M.) (M.) (M.) (M.) (M.) (M.) (M.) (M.) (M.)
=== ==== == ==== ==== ==== ==== ==== ==== ==== ==== ====
sio NYAL A .0780 .0000 .0000 .0960 .0000 .0000 5.2160 .0000 .0000
IGS NYAL A .0780 .0000 .0000 .0960 .0000 .0000 5.2160 .0040 -.0010
sio QAQ1 A .1080 -.0002 .0001 .1267 -.0003 .0002 .0000 .0000 .0000
IGS QAQ1 A .1080 -.0002 .0001 .1267 -.0003 .0002 .1206 .0000 .0000
sio WUHN A .1100 .0000 .0000 .1280 .0000 .0000 2.3610 .0000 .0000
IGS WUHN A .1100 .0000 .0000 .1280 .0000 .0000 2.3610 -.0094 -.0022
The following file has no antenna conflicts: emr12127.snx (emr).
--
David Hutchison
Geodetic Survey of Canada
Ottawa, Ontario, Canada
Internet: hutch at geod.emr.ca
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