The binary flare star AT Mic has been observed with the VLA (5 GHz and 1.5 GHz) and, nearly simultaneously, with the MOST (0.843 GHz). There appears to be a slowly varying component of the radio intensity, with a flux density greater at 0.843 GHz than at higher frequencies. It is suggested that above 1 GHz the emission is possibly produced by incoherent gryosynchrotron radiation, whereas below 1 GHz a coherent mechanism predominates.

Since the start of high-resolution observations with the radioheliograph at the Culgoora Solar Observatory it has been noted that some bursts which occur from separate active regions could be physically correlated. It was suggested that the time delay between the correlated bursts is of the order of seconds, and that fast electrons provide the trigger. Wild found that shortly before a large flare weak bursts, stronelv polarized in the same sense, appeared simultaneously in different sources after a quiet period and he discussed the phenomenon in the light of flare mechanisms.

Observations of five cepheids in Crux are described and annual epochs of maxima presented. The O–C diagram of S Crucis shows changes between two alternative periods. The observing method appears suited to sites with only a limited number of hours available.

In 1994 December we installed a Celestron CG11 Telescope at Belgrano Base (previously called Belgrano II) for site seeing measurements and variable star observations. We describe the project, logistics, installation and working environment. We present the first quantitative observations of astronomical seeing conditions at Belgrano Base.

A complete orbital light-curve of V2051 Oph in the IR H band is presented, together with a second eclipse in the J band. Simultaneous Rc band data were obtained. Eclipse depths in Rc, J and H are 1.8 mag, 1.0 mag and 0.8 mag respectively. No evidence for ellipsoidal variations due to the secondary was seen and constraints on the secondary are discussed.

The astrophysical literature contains many discussions on exactly which changes in a star’s structure are responsible for the extremely large radii found after core hydrogen exhaustion. Different authors favour different mechanisms. Unfortunately none of the proposals are easily verified nor are they easily disproven. In this paper we examine the suggestion that it is the increased central mass concentration (i.e., the growth of the hydrogen exhausted core) which is the primary agent responsible for envelope growth.

This year the School of Electrical Engineering began observations with the new Fleurs compound interferometer. This instrument operates at 21 cm and has a fan-beam response 35″ arc wide in an east-west direction.

The most recent helium abundance determinations in main sequence B stars are those of Hardrop and Scholtz, Kodaira and Scholtz, Norris, and Leckrone. Their results indicate that it is possible to assign a helium abundance which is characteristic of all B stars. Norris and Leckrone worked with a number of B stars ranging from B0 to B9, and both have assigned a characteristic helium abundance to the B stars. Norris derived a value, A = 0.088 ± 0.012, and Leckrone a value of A = 0.106 ± 0.01, where A is the abundance of helium relative to hydrogen by number.

The purpose of this paper is to obtain an expression for the reflecting properties of a semi-infinite, plane parallel, isothermal atmosphere of scattering factor λ. The absorption and scattering of the incident radiation is assumed to be entirely due to transitions in two-level atoms, and the absorption and emission profiles are given by <f>(y), y being frequency from line centre in Doppler units.

Observations at a number of frequencies indicate that for at least two pulsars the average pulse shape has a slow but quite definite frequency dependence. Figure 1 shows average pulse shapes for CP 1919, CP 0950 and CP 1133. With the exception of those at 408 MHz these results were obtained at Parkes. The 408 MHz pulse shapes were obtained at Jodrell Bank by Lyne and Rickett. Circumstances of the observations are listed in Table I. Linearly polarized feeds were used at all frequencies.

A number of New Zealand universities offer astronomy courses at different undergraduate levels. The courses are taught in Physics or Mathematics Departments. Some are only sub-courses within a physics major rather than a dedicated astronomy course. I will detail these and show material relating to the course content and some of the texts used. Postgraduate programs in astronomy are also offered, principally at the University of Canterbury but also at the University of Auckland and Victoria University of Wellington.

The complex consisting of the bright HII region M17 (G15.0-0.7) and its associated molecular cloud is well known as a region of active star formation which contains an abundance of many different molecules (see e.g. Lada 1976). For H2CO, observations of the 110 – 111 transition at 4.8 GHz towards the HII region show an intense narrow absorption feature with a radial velocity near + 24 km s−1 superimposed on weak absorption which extends to below +10 km s−1 (Whiteoak and Gardner 1970). According to Whiteoak and Gardner (1974) the latter consists of several features centred at the velocities of +4.7, + 10.4, + 17.9 and +20.3 km s−1. Lada and Chaisson (1975) mapped the absorption around M17 with a 6′ .5 arc beam and concluded that the broad component was associated with the obscuring dust cloud near the HII region while the narrow feature occurred in a foreground cloud. In this paper we present observations made with higher angular resolution and higher sensitivity; they define better the H2CO distribution and its relationship with the extended CO cloud near M17 (Elmegreen et al. 1979).

The aim of this work is to investigate certain assumptions that have been made in calculating line profiles and equivalent widths of neutral helium lines in early type stars. The effect of electron scattering on the continuum flux is investigated and a curve of growth analysis carried out to study this effect. The theories involved in calculating the line absorption coefficient are also investigated.

The β Cep variables are characterised by light variations of a few per cent and velocity variations of up to a few tens of km/s over periods of from about 2.5 to 7 hours. Spectral types range from BO to B2 and luminosity classes from IV to II-III, corresponding to masses from 8 to 18 M ⊙. The light and velocity curves are 90° out of phase, so that maximum light (and also maximum temperature) occur at minimum radius.

Several extragalactic HI surveys using a λ21 cm 13-beam focal plane array will begin in early 1997 using the Parkes 64 m telescope. These surveys are designed to detect efficiently nearby galaxies that have failed to be identified optically because of low optical surface brightness or high optical extinction. We discuss scientific and technical aspects of the multibeam receiver, including astronomical objectives, feed, receiver and correlator design and data acquisition. A comparison with other telescopes shows that the Parkes multibeam receiver has significant speed advantages for any large-area λ21 cm galaxy survey in the velocity range range 0–14000 km s−1.

Observations for the Parkes 2700 MHz catalogue are carried out in two stages: (i), a relatively fast finding survey, followed by (ii), accurate measurement (at 2700 MHz) of flux densities and positions of the sources on the survey scans. For the first six parts of the catalogue intervals of several weeks between the stages resulted from the necessity to reduce the (analogue) survey scans manually. This communication describes a computer program which records and reduces these scans, and which produces an on-line map and source listing for the survey region. Thus the measurements of the second stage may be carried out immediately after the survey; additional advantages provided by the technique are discussed later in the paper.

Centaurus X-3 was first observed by Chodil et al. in the energy range 2-9.5 Kev in 1967. Subsequent observations by Cooke and Pounds in the energy range 1-12 Kev snowed that the source was variable. Periodic X-ray pulses from Centaurus X-3 in the energy range 1-20 Kev have been discovered by Giacconi et al. They found that 70% of the X-ray energy was emitted in a pulse during 30% of a cycle. The length of the cycle is about 4.84 sec, but it was found to change by ~0.1% in a few days and by ~1% in three months. The X-ray data locate the source at 11h21.8m -60°25.8′ (1950) with an error of ±5′ arc.

In discussions of the non-radiative propagation of energy through stellar atmospheres hydromagnetic waves, or in their more specialized form Alfven waves, have played an increasingly important role. Parker (1974) has suggested that they provide the cooling mechanism for sunspots, while Piddington (1974) has attempted to explain the flare energy supply in terms of hydromagnetic energy transport. While most analyses assume a homogeneous magnetic field extending to infinity in a compressible but unstratified atmosphere, it is important to remember that most astrophysical plasmas are gravitationally stratified and that the magnetic fields are highly inhomogeneous, exhibiting a variety of different structures.

This paper presents a progress report on a programme of infra-red photoelectric photometry of the red giant sequences in some southern globular clusters. As measured in B and V these sequences are known to differ from cluster to cluster, at least one contributing factor being differential line-blanketing arising from variations in metal abundance. Observations in R and I should be substantially free of blanketing, and so enable us to eliminate this factor, clarifying the situation and making possible a more accurate transformation of the observations to the Mbol , log Tett plane. The difficulty of making this transformation has been a major obstacle in comparing observations and theory for cluster giants.