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IERS Message No. 439                                       July 21, 2021
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Local Survey metadata project


Dear colleagues,

In the scope of the activity of the IAG Working Group "WG 1.2.1
Methodology for surveying geodetic instrument reference points (joint
with IERS)", co-location site survey results and survey product metadata
are being collected.

The objective is to give an easy access to local tie products and to
standardize metadata that are currently not available or included in
separate survey reports. A database of local tie product metadata is
under construction. It will be available online in the future.

If your group made such a survey and produced local tie vectors or SINEX
files at some ITRF co-location sites, we would be grateful if you could
fill the metadata form which can be found at this web page:

https://itrf.ign.fr/local_survey_metadata.php

Survey reports that we know about are also posted at the following web
page: https://itrf.ign.fr/local_surveys.php . They are a valuable source
of information for terrestrial reference frame producers and a source of
inspiration for surveyors who have to make such a survey. Do not
hesitate to create a web page for your group and we will add a link to
it to give proper credits to your valuable work.

Please note that we are interested in all surveys including the old
ones. Even if consecutive surveys provide consistent tie vectors (in
case of frequent local tie surveys), our objective is to collect all
available local tie products, SINEX files, associated metadata, reports.

We also think that this metadata collection is an opportunity to start
collecting survey "raw data" for potential future projects. While having
local tie raw data available was though useful for several reasons in
the past (notably adjustment software comparisons, reprocessing), they
have never been collected due to lack of data standardization for survey
raw data. Our current objective is simply to archive those data as they
are in order not to lose data.

Thank you for your help,

Best regards,
The ITRS Centre


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