The Parkes 64-m antenna has been used to map ammonia emission in the (J,K = 1,1) and (J,K = 2,2) transitions toward molecular cloud complex NGC 6334. This complex contains a number of OH and H2O masers, HII regions and IR sources, and is a rich source of molecular line emission.

Distributions of observed and derived quantities are presented with a linear resolution of ∼ 1 pc. Velocity anomalies are present near the two OH masers NGC 6334A and B, and the source of ammonia emission located near the northernmost H2O maser is one of the most intense sources of NH3 emission in the Galaxy.

The binary X-ray source GX 1 + 4 was observed during a balloon flight in 1986, November. The source was in a relatively high intensity state. Time analysis of the data shows that the pulsation period was 111.8 ± 1.0 s indicating that one or more episodes of spin-down occurred between 1980 and 1986. Folded pulse profiles are very broad with an indication of a notch at the peak. Evidence has been found for a correlation between hard X-ray intensity and phase of the proposed 304 day orbital period. The time averaged intensity since 1980 is an order of magnitude lower than during the 1970’s. A survey of the post 1980 data shows that several reversals of the period derivative have occurred. Spin-up at the rates typical of the 1970’s has been followed by a dramatic spin-down episode with dP/dt>2.4 × 10−7 s/s.

The role of astronomy in the cultural exchanges between India and China through several centuries is taken as an example of astronomy shaping human life. Then the tradition of astronomy in the development of scientific thought is examined. The contribution of astronomy in shaping the post-Renaissance society is briefly introduced. It is concluded that the recent developments of ideas in cosmology throw light on the intrinsic nature and limitations of the scientist as a human being.

Bursts of gamma rays lasting from a fraction of a second to several seconds have been observed by spacecraft since 1967 (Klebesadel et at. 1973). Events with fluxes in excess of 10−4 erg cm−2 s−1 are seen at the rate of several per year for gamma ray detectors with an energy threshold of ˜50 keV. The sources of these bursts remain unidentified and the mechanism(s) responsible for the production of the gamma rays remain(s) in the realm of conjecture. (For a review see Ramaty and Lingenfelter 1982).

Spectrometers give information on the chemical composition and physical properties of celestial objects. The Earth’s atmosphere restricts the observable spectra to windows in the absorption. Most of these windows are less than one octave wide. To increase the amount of information gained, it is necessary to increase the resolution of the spectrometers. With the advent of balloons, rockets and spacecraft, it is possible to make observations free from atmospheric absorption and it is possible to gain more information by increasing the bandwidth of spectrometers. This paper describes an infra-red Fourier transform spectrometer. The interferometer has a bandwidth of over one decade, from 500 to 5,000 cm-1, with a maximum resolution of 10 cm-1. The resolution can be electronically controlled. There are no absorbing or refracting parts in the interferometer and the resolution is limited by mechanical considerations.

The Parkes interferometer consists of the 210-ft para-boloidal reflector of the ANRAO, and a 60-ft paraboloidal reflector mounted on rail tracks. These extend from 400 ft to 1400 ft from the 210-ft paraboloid and run both north-south and east-west. The baseline may be continuously varied during observation; receivers operating simultaneously at 468 and 1402 MHz enable the determination of complete visibility functions over the range 200λ to 2000λ.

The history and achievements of interferometric angular diameter measurements have been reviewed recently by Hanbury Brown (1974) and only a brief outline will be given here. As the title is intended to imply, the present discussion will be limited to interferometry involving baselines in excess of telescope aperture diameters.

Following the ‘prompt’ radio outburst seen soon after the neutrino emission in SN 1987A (Turtle et al. 1987), we initiated a program to monitor the supernova at the Tidbinbilla Deep Space Communications Complex at 8.4 GHz in a search for radio emission from the expanding remnant. No radio emission has been detected to date (DOY 151, May 30 1988).

A knowledge of the on-ice seeing is a key requirement for planning future Antarctic observatories. In this paper we discuss the likely negative impact on seeing produced by the development of the deep winter surface temperature inversion (Ekman layer). The Automated Astronomical Site Testing Observatory (AASTO) will deploy, as one of its complement of site-testing instruments, an automated differential image motion monitor (DIMM) telescope designed to generate seeing data throughout the Antarctic winter. Here we describe the multi-aperture concept which has been developed for this mission, and touch upon some of the critical technological considerations associated with the low power budget and with the requirement of autonomous operation at very low temperature (–90°C).

There exists a large number of varying methods of solution in radiative transfer theory. House and Avery have recendy published an exposition of the Monte-Carlo technique and the very nature of this solution makes it readily amenable, in theory, to the study of any transfer problem. Grant and Hunt have developed a method involving the invariant Sn matrix transformation and this also appears quite general in its application. Further, the Riccati transformation technique, developed by Rybicki and Hummer, has already been used in solving several different transfer problems. However, these methods have certain disadvantages. The equations are of first order and thus stability difficulties arise. Also, the finer details of the method rely, to a large extent, on the particular problem under consideration, and experience with such a method is required for the efficient computation of solutions.

Over the past years considerable information has been acquired concerning the structure and magnitude of sunspot magnetic fields; however, there is a paucity of data concerning the motions of the seats of these fields, i.e., individual umbrae within a spot group. The well-known effects of differential rotation cause sunspots to diverge with time in longitude at a daily rate of, at most, a few degrees per solar rotation. On the other hand, a limited number of investigations have shown that individual umbrae can have proper motions of up to 100 to 200 m/s, or about ten times greater than effects of differential rotation. In addition, equally limited observations have shown that umbrae sometimes rotate about an axis through their centre; in an extreme case the rotation reached 30°/day. The last large sunspot group of the last cycle, having Central Meridian Passage 20.5 September, 1963, has been studied by means of photoheliograms and magnetograms obtained four days before and four days after CMP at the Crimean Astrophysical Observatory. The magnetograms show the distribution of both the transverse and longitudinal components of the magnetic field in the activity region. In this study we have studied umbral motions and their relation to the magnetic field.

Frequency dependent structure is not uncommon in observations of extended radio sources. Where a source consists of two components with different spectra at an angular separation considerably less than the resolution of the telescope, the centroid position will vary systematically with frequency. A well-known example is 3C 273 though the effect in this case is quite small. With beams of a few minutes of arc, larger position differences could occur between measurements made at widely separated frequencies without the source being noticeably resolved. In a preliminary study of a sample of 120 4C radio sources, Munro and Hoskins found 17 cases of discrepancies in the range 45 to 100 seconds of arc between positions measured at 408 MHz with the Molonglo cross (beam width ~3′ arc) and at 2700 MHz with the Parkes 64 m telescope (beam width ~7′ arc) by Wills and Bolton. These separations were considered to be significant in terms of the quoted errors which were typically 10 to 15″ arc in each coordinate for both sets of measurements. It was pointed out that to explain the results on the basis of a double source model it would be necessary for the two components to differ in spectral index by ~1.

Recent reviews have demonstrated that a wide ranging selection of objects emit a major proportion of their energy at wavelengths longer than 1 µm, including such intrinsically different objects as late type stars, Be stars, F supergiants and novae. In the majority of cases the infrared radiation has been interpreted in terms of thermal radiation from a circumstellar shell of solid ‘dust’ particles. Any attempt at a detailed comparison of theoretical energy distributions with observed infrared photometry encounters the problems of uncertainties in the absolute calibration, and limited accuracy of the observations.