The general perturbations of the asteroids of the Flora group (975″ < n < 1150″, n - the mean daily motion) due to Jupiter have been automatically computed on an IBM 4341 computer with the Hansen method by manipulating Broucke’s Symbolic Poisson Series Processor, and the results have been compared with that computed previously with the Bohlin group method.

The authors discuss the light-pollution prevention ordinance passed by the Japanese town of Bisei in 1989.

The observations in this paper were carried out as part of a program co-ordinated by the Occultation Section of the Royal Astronomical Society of New Zealand.

On 6 August 1989 minor planet (9) Metis occulted the magnitude 8.7 star SAO 190531. The occultation was observed by two visual observers in Tasmania, and at one photoelectric and two visual sites in New Zealand. From the five chords obtained we have deduced an average cross-sectional diameter for this minor planet of 173.5 km at the time of the occultation. This is in good agreement with previous radiometric and polarimetric results.

This paper describes the plans for a planetarium and observatory at Sydney’s Macquarie University.

An attempt has been made to examine the nature of 3-minute umbral oscillations in order to identify their origin. For this purpose we have calculated, on the basis of Musielak and Rosner (1987), the fast-mode energy spectra generated in a typical sunspot convection zone (Yun 1968). The computed energy spectrum is fed into the lower boundary of the sub-photospheric resonant cavity to examine the characteristics of the wave propagation through the SS umbral atmosphere (Avrett 1981). The upward velocity spectra computed at various heights are presented and their behaviour compared with observations.

One of the two main telescopes at Sydney Observatory is a computer-controlled 35.6-cm Celestron. It is used with a television-type system. There is an integrating CCD camera available as well as an ordinary TV camera for bright objects. The images from the cameras can be shown in the Observatory’s lecture room. They are first put through an image processor which allows constant enhancement, spatial filtering and the recording of images for use on cloudy nights. Preliminary results are encouraging, and show the value of the system, even in Sydney’s highly light-polluted sky.

Film copies of original astronomical plates taken with the 1.2-metre UK Schmidt Telescope (UKST) at Siding Spring Observatory, New South Wales have been used for several years at Edinburgh University. Two teaching packages are intended for undergraduate use; the educational packages are mainly designed as visual aids for colleges, schools and amateur groups.

The Extreme Ultraviolet Explorer (EUVE) is a NASA funded astronomy mission which will operate in the 70–760Å spectral hand. The science payload has been designed and built by the Space Sciences Laboratory at the University of California, Berkeley and consists of three grazing incidence scanning telescopes and an EUV spectrometer/deep survey instrument.

We give an overview of the planned mission profile and briefly discuss the instrumentation which comprises the science payload. The EUVE is scheduled for launch in late August 1991.

We describe the application of Peltier effect cooling to charge coupled device (CCD) detectors. We are developing this technique to produce a CCD camera which requires low maintenance, yet has sufficiently small dark-current for long exposure imaging. This camera will be used in an automated imaging telescope at Siding Spring Observatory. The design principles used to maximise cooling of the detector, and hence minimise dark-current, are discussed. A small dark-current can be obtained only if great care is taken to reduce or eliminate convective, conductive and radiative heating of the chip. In addition, a path of high thermal conductivity must be provided for the heat removed from the CCD. A recent laboratory test of our cooling system demonstrates that careful design can lead to sufficiently low CCD dark-current for many astronomical applications.

In 1988, a very powerful and versatile coudé echelle spectrograph was installed at the Anglo-Australian Telescope. Since then it has been winning about 30% of AAT time and has been highly productive scientifically. Therefore, using a coudé auxiliary telescope (CAT) to give the spectrograph more use and to free the AAT for other work is a very attractive possibility, particularly if the CAT can give a sensitivity similar to that obtained with the 3.9-metre telescope. While a conventional CAT with such performance would be very expensive, a much cheaper instrument should approach this goal, at least for high resolution spectroscopy. Even so, the cost could not be met in a reasonable time within the AAO’s budget; hence, additional international collaboration is being sought.

We have successfully demonstrated optical aperture synthesis at the 4-m Anglo-Australian Telescope. By using a multi-hole mask over the (re-imaged) primary mirror and recording the resulting fringe patterns with high time resolution, diffraction-limited images of sufficiently bright objects can be reconstructed. The data processing uses closure phases to overcome the effects of atmospheric turbulence. We show an image of the double star η Oph, with component separation 0″.45.

A Photometrics CCD system containing a TH7882 chip has been in use at Mt John since 1989 October for imaging photometry. Extra control software has increased observing ease and image-header information. Photometrically the system appears to be performing satisfactorily. The blue helium star LSS 99 showed no variation exceeding ~ 1% over 40 min of observation. The blue eclipsing binary HV 1761 in the Small Magellanic Cloud is found to have approximately equal components.

We have extended the integration time of a Philips type 56470 video camera to make it useful for visual offset guiding on 0.6- and 1-metre telescopes.

The PKSCAT90 database consists of radio and optical data for 8264 radio sources. It covers all the sky south of declination +27 degrees. Most of the galactic plane and the Magellanic Cloud regions are excluded from this catalogue but have been the subject of other specialised surveys. A few data errors in the initial PKSCAT90 version 1.00 released in March 1990 have been corrected in the current version 1.01 edition.

This paper describes a system utilising a sapphire-loaded superconductor cavity to provide a high-stability oscillator signal for use in VLBI observations.