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=?iso-8859-1?Q?Ferland=2C_R=E9mi?= 12-Mar-2008 20:43
Subject : [IGSSTATION-2142]: IGS05 Review - AMC2 - COCO - GLSV - HYDE - (28450)
FROM . =?iso-8859-1?Q?Ferland=2C_R=E9mi?= - RFerland@NRCan.gc.ca
Date : 12-Mar-2008 20:43 -
To : igsstation@igscb.jpl.nasa.gov
Stations : AMC2, COCO, GLSV, HYDE
IGS Station Mail 12 Mar 12:43:31 PDT 2008 Message Number 2142

Author: Remi Ferland

Dear IGS Colleagues,

Discontinuities have been observed over the last few
months on the Reference Frame stations listed below. They have
been reported in the discontinuity table. There is, in general,
a delay of ~5 weeks to have a good confidence that the change
is +-permanent. The addition of a discontinuity automatically
cause the reference frame station not to be used for the
igs weekly combined solution. However, it continues to be
used for the alignment of the weekly updated cumulative solution.
The weekly AC solutions are recombined regularly, allowing the
official cumulative solution reflect the discontinuity at the time
that they happened.


Date & Cause:
07:274:77431 (Wk 1447) Antenna & Splitter Change.
Effect ~5mm in the NS direction
Implemented on Wk 1452.

Date & Cause:
07:259:00000 (Wk 1445) Unknown
Effect ~9mm in the NS direction
Implemented on Wk 1453.

Date & Cause:
07:317:00000 (Wk 1453) Antenna & Receiver Change
Effect ~6mm in the NS direction & ~3mm H direction
Implemented on Wk 1454.

Date & Cause:
07:336:00000 (Wk 1456) Unknown
Effect ~4mm in the NS direction
Implemented on Wk 1462.

Date & Cause:
07:333:00000 (Wk 1455) Antenna & Receiver Change
Effect cannot be estimated due to missing data between
weeks 1416 and 1454.
Implemented on Wk 1462.

Date & Cause:
07:112:00000 (Wk 1424) Unknown
There is still some doubt that there is actually a discontinuity!
Implemented on Wk 1431.

Date & Cause:
07:235:51420 (Wk 1441) Antenna Change
Effect ~8mm in the height component.
Implemented on Wk 1446.

Note that the discontinuities reported are predominantly
in the NS direction. An inventory of all "observed"
discontinuity for all IGS stations can be found in
the usual location:

ftp macs.geod.nrcan.gc.ca
cd /pub/requests/sinex/discontinuities

The files are updated as needed.

Best Regards,