Subject: [IGSMAIL-1636] New station WSRT at Westerbork, the Netherlands
From: Boudewijn Ambrosius and Danny van Loon (DEOS/DUT)
Date: Thu, 26 Jun 1997 9:02:11 PDT

******************************************************************************
IGS Electronic Mail      Thu Jun 26  9:02:11 PDT 1997      Message Number 1636
******************************************************************************

Author: Boudewijn Ambrosius and Danny van Loon (DEOS/DUT)
Subject: New station WSRT at Westerbork, the Netherlands

Dear colleagues,

On June 26, 1997, a new station has become operational in Westerbork,
the Netherlands. It is situated at the premisis of the 'Westerbork
Synthesis Radio Telescope' (WSRT), which falls under the responsibility
of the ASTRON organization in the Netherlands. We have decided to use
the WSRT acronym as the 4-character ID of the station. It will be operated
by the 'Delft Institute for Earth Oriented Space Research' (DEOS) at
'Delft University of Technology' (DUT) in the Netherlands, which is
also already acting as the operational center for KOSG, IRKT and MDVO.

The new station WSRT has been established because DUT has decided to close
down its facility in Kootwijk (KOSG), probably next year. Of course we
regret this decision, but it is necessary for reasons of cost reductions 
and to enhance the efficiency of the organization. KOSG has been active 
as a GPS station since the early days of IGS and it already participated 
in the GIG-91 campaign. Its reliable and successful operations were the
main reasons why it received the status of 'core' station in the global
IGS network. We would like to transfer this role to the new WSRT station
which is only 100 km away from Kootwijk. In order to ensure a smooth
transition, we will try to keep both stations running in parallel for
at least one full year. Therefore, we would like to call on all the IGS
data analysis centers to start including WSRT in their analyses immediatly.
From our part, we will invest a strong effort to determine an accurate
tie between KOSG and WSRT. This will include mobile SLR colocations at
both stations and possibly special measurement campaigns with Water
Vapor Radiometers, to improve the vertical connection.

In fact, WSRT has the potential to become even a better station than
KOSG. One of the reasons is that the external frequency standard for
WSRT is a Hydrogen Maser, whereas KOSG relies on a Rubidium clock. In
addition, the radio telescope, on which grounds the new station is hosted,
will also start to make VLBI observations in the near future, thus 
providing an direct colocation with another important space-geodetic
technique. Furthermore, regular colocations with mobile SLR are planned
and the station will also be equipped with a gravimetric platform. It
will be designated the status of principal geodetic reference station
for the Netherlands, as soon as all techniques are operational, and so
it will take over the role of Koowtijk.

The antenna of the GPS system at WSRT is mounted on a 18 m long mast,
standing on a concrete platform which is firmly embedded in a geologically
stable sand layer. The vertical position of the antenna is stabilized
with an Invar-wire/spring system, similar to the construction used in
Metsahovi (METS). The GPS system consists of an Allan Osborne
TurboRogue SNR-12 RM receiver (ser.no. 209) connected to a Dorne Margolin T
chokering antenna (ser. no. 273). As already mentioned, the external
frequency standard is provided by a Hydrogen Maser, which is also the
primary reference for the radio astronomical observations at this site.

The approximate coordinates of the station are (in WGS'84):

X = 3828739 m
Y =  443305 m
Z = 5064887 m

and the height of the antenna reference point (bottom of chokering)
above the geodetic marker on top of the mast is 379.5 mm. A station
log sheet with complete information will be submitted at the end of
next week.

As of June 26, 1997 (DOY 177), the data will be submitted to the
European Regional Data Center at IfAG in Germany, which will take care
of further distribution to the IGS community. Test data which have been 
collected since May 2, 1997, will be available on request. Requests
should be sent to: [email-masked].

Last but not least we would like to thank all the organizations and
individuals in the Netherlands who have worked hard to realize this
new high-quality station. We hope it will provide a valuable contribution
to the IGS and that it will last for a very long time.

Boudewijn and Danny

[Mailed From: Boudewijn Ambrosius <[email-masked]>]