[IGSSTATION-8709] WSRT00NLD - Antenna change

[Hans van der Marel]

Author: Hans van der Marel

Dear Colleagues,

Today 7 December, 2023 (between 10 and 13 UTC) the old Dorne Margolin T antenna at the IGS station WSRT00NLD was replaced by a modern LEICA AR25-R4 :

Antenna type : LEIAR25.R4 LEIT
Serial number: 726840
Antenna height: 0.3754      (changed)

Radome serial number: 765734

The Dorne Margolin T was installed more than 25 years ago, in 1997. As expected, it was impossible to separate the old antenna from the monument without some reconstruction work. The latter involved replacing a metal adapter with a newly fabricated adapter. As a consequence the antenna height changed.

We are fairly confident that the new adapter did not introduce noticeable changes in the horizontal position: any differences, if they exist, should be below the millimeter level.  In the vertical, the ARP of the new antenna is 13.4 mm below the old ARP, but this is absorbed in the modified antenna height.

The old and new antenna positions have been checked by a local survey and a local GNSS monitoring network. The local GNSS monitoring network consists of two receiver at distances of several hundreds of meters, that started observing two weeks before the change and continue observing for some time after the change. Results from the local survey and GNSS monitoring, which is ongoing, are not available yet. These will be an independent verification of the work that was done.

A new station logfile will be submitted soon.

Finally, I would like to thank my colleagues from the Dutch Kadaster who took it upon them to prepare, and monitor the antenna change.

Hans van der Marel
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