The NZRG's first aim was the setting up of a two-element (East-West)
astronomical interferometer on the CIT campus (see also Research Context).
Two f/0.4 ex-satellite-tracking antennae and associated equipment were
applied to this. Equatorial mounts were imported from the disused
radiohelioscope at Culgoora, as operated by CSIRO Radiophysics Laboratories,
Australia.

Though early experiments with the solar emission in C-band (4 GHz) using a
~250m baseline were unconvincing, the experiment succeeded on a shorter (8m)
baseline and has been written up (Thresher et al, 2002) (First results shown
below).

 Solar interferogram from 8m baseline setup (November 2001).

The LNBs (EchoStar model 950) are sensitive to a bandwdith of some 400 MHz
centered at around 4 GHz. With technical input from the company 4RF of
Wellington, the local oscillator of one LNB was deactivated and replaced by
an amplified signal sourced from the local oscillator of the other, fully
functional LNB. In this way, a single mixed conversion frequency (around 5.1
GHz) was used to shift the amplifier outputs to a 400 MHz band centered at
1.1 GHz. These downshifted outputs were fed into a passive IF combiner
block. The common output was connected to a commercially available diode
detector, designed as an aid for positioning of antennas for TVRO signal
reception.

At the Regional Meeting of the IAU in Sydney in 1990, there was a proposal
for a relatively large sum for a New Zealand-based Very Long Baseline
Interferometry (VLBI) "leg" to the Australia Telescope National Facility.

This proposal was well received scientifically, and remains as a key goal for
the longer term, but this purpose requires the development of an
infrastructure of interest and support. This is a basic purpose that the
NZRG attempts to address.

The relatively large engineering requirements of radioastronomy seek
appropriate experience. This has been sought from tertiary sector
organizations in the Wellington region. The Group was based at the former
Central Institute of Technology (CIT) in Upper Hutt, and included several
former CIT members of staff on its board.

The 5m dishes and receivers came from the estate of a local amateur
enthusiast (Ray Illingworth). Software for a control system for directing
the antennae to targets of interest was devised by 3rd year electronics
students at former-CIT. Another former-CIT student built a broad band, high-
gain amplifier, based on the design given in William Lonc's guide book
Radioastronomy Projects (St Mary's University, Halifax, NS).

Academic aims of the Group were outlined in the article of Budding &
Roberts (1996). This was updated by Budding (1998), and a more recent
summary of the Group's aims and background can be found in Dodson &
Budding's RASNZ Annual Conference 2000 ("Spacetime 2000") paper. Still more
recently there have been determinations of the lunar subsurface temperature
cycle (Budding et al., 2000) and observations of the strong microwave
enhancement due to solar active region 9393 (Wellington Astronomical
Society Newsletter, April edition, 2001).

Current Project: Radiometric Study of Geostationary Broadcasting
Satellites in the Longitude Sector 140 E to 140 W.

Physicists have noted anomalies in the conventional explanation of gravity.
There may be measurable negative effects on the stability of satellites in
geostationary orbits. A radiometric high accuracy positional study would
provide fundamental understanding and solutions to mitigate these effects.
We therefore propose a radio frequency observational study to locate
geostationary broadcasting satellites by high-accuracy signal timing from
three 5m-dishes at these locations: NZ International Campus in Upper Hutt,
Pohangina Valley Facility, and Mt. Taranaki.

Our resulting high-precision data will have relevance to geophysical studies
(continental drift, plate tectonics, crustal stresses that cause earthquakes
and tsunamis).

Scientifically, this concerns refined aspects of motion-under-gravity. By this,
we refer to data that can bear on:
(a) The figure of the Earth, including its density distribution from core through
to upper atmosphere (particularly Pacific region) and the Earth's
rotation structure,
(b) Full dynamics of the Earth-Moon system,
(c) The solar gravitational field, the solar wind and radiation pressure,
(d) Effects of other planets or other components of the solar system,
(e) General Relativity effects in gravitation.

Any departures from established theory or unknown contributions to the net
gravitation (see e.g. Cover Article of 'New Scientist' November 27, 2004).

Possible longer-term observing applications could include the surveillance of
radio-bright sources (cf. e.g. Slee et al., 1994). Early results show how
the solar rotation rate can be determined, and insights into the nature of
the lunar surface rocks gained, from simple broadband microwave single-dish
measurements (Dodson & Budding, 2000). Direct inferences on the physical
properties of a few bright cosmic sources are also possible by considering
their measured flux densities.

Budding, E. and Roberts, E., 1996, Southern Stars, v36, 275.

Budding, E. 1998, Southern Stars, v38, 62.

Budding, E., Dodson, A. and Trethowen, H., 2000, Southern Stars, v39, 36.

Dodson, A.W. and Budding, E., 2000, Southern Stars, v39, 21.

Davidson, G., 1994, M Sc Thesis, Waikato University.

Jiricka, K., 1992, Bull. Czech. Inst. Astron., v81, 1.

Lonc, W.P., 1996, Radio Astronomy Projects, Radio-Sky Publishing.

Roberts, J.A., Hajsaleh, J. and Benge, R., 1994, J. Roy. Astron. Soc. Canada, v88, 233.

Slee, O.B., Sadler, E.M. Roberts, J.E. and Ekers, R.D., 1994, Mon. Not. Roy Astron. Soc., v269, 928.

Storey, J.W.V., Ashley, M.C.B., Naray, M. and Lloyd, J.P., 1994, Amer. J. Phys., v62, 1077.

Thresher, W., Wheatley, M., and Budding, E., 2002, CIT Occasional Papers Ser.., No 28.