An update on Siting of International Distributed Radio Telescopes
Planned Facilities
There are
currently two significant distributed radio telescopes being planned which
require extensive protected areas:
1.
LOFAR
- the Low Frequency Array, a mini-SKA operating at low frequencies between 10 -
220 MHz. It is an initiative of the NFRA (the Netherlands) and several
organizations in the USA including the Naval Research Laboratories (this
organisation requested the WA Government to participate in radio-quietness
tests for LOFAR as an add-on to the SKA tests). The final date for siting
proposals is September 2002.
2.
SKA -
the frequency range of coverage is assumed to be approx. 150 - 1500 MHz for
Mid-SKA, and 1-23 GHz for High-SKA, with a proposal for siting required by
2005.
Both LOFAR and SKA require protection for the closely spaced antennas on
the central site. The maximum extent of LOFAR is 350 km, and the SKA extends to
continental distances (in its final form). Australia has a number of suitable
areas, which could accommodate the SKA and also LOFAR (if requested by the
LOFAR consortium).
The SKA - international
activities
The ISSC
(International SKA Steering Committee) has appointed a Site Evaluation and
Selection Committee (SESC) with a representative from each country potentially
interested in hosting:
- Northern hemisphere: Europe,
China, India, USA
- Southern hemisphere: Australia,
South Africa.
Australian siting issues
In addition
to the interest of Western Australia in providing a site for LOFAR and SKA, South
Australia is currently preparing a case for funding to carry out site
investigations for the SKA. This will include a radio-quietness testing
program. A possible site near Lake Frome, NW of Broken Hill may be investigated
first. Broken Hill is also interested in the possibility of being a
"base" for engineering services, so that a site in New South Wales
between Tibooburra and White Cliffs may be investigated.
Progress in Western
Australia
Two
adjacent areas in the Murchison between Geraldton and Meekatharra have
provisionally been set aside by the Western Australian Government as possible
sites. Investigation is proceeding for an area east of Kalgoorlie north of the
Transcontinental Railway.
The Western
Australian Government also appointed a contractor to undertake an intensive
three-week high-sensitivity measurement program to determine the amount of
"used" spectrum. The program was undertaken on Mileura Station, 100
km west of Meekatharra, during March-April this year. Not all the data has yet
been analysed, but the services which are in evidence over the 30 to 1810 MHz
frequency range are:
- Satellite downlinks
- TV, FM
- Telstra phone/fax/email
services to homesteads
- Aircraft communications
(short-period)
However,
the proportion of "unused" spectrum, to the sensitivity limits of the
measuring system, is given below (the band 350 - 1060 MHz has not been fully
analysed yet). The proportion of unused spectrum is seen to be very high.
It is
planned to carry out further tests in the second area in the Murchison,
possibly in March 2002. This program will include sample testing the spectrum
which appears to be unused, with an equipment configuration having higher
sensitivity.
Acknowledgement
The
assistance of Aaron Chippendale in analysing the data provided by the
contractor is gratefully acknowledged.
Bruce MacA
Thomas
SKA Site
Engineer
