HD 44179, a ninth-magnitude star of late B spectral type, is peculiar in several respects. At red wavelengths it appears to be located at the apex of a biconical nebular (‘The Red Rectangle’) of dimensions about 1′ arc. Cohen et al. (1975) identified the system with the bright infrared source AFGL 915 and carried out investigations at optical, infrared and radio wavelengths. The complexities of the spectra have continued to interest astronomers.

NGC 4945 is a ninth-magnitude southern galaxy orientated almost edge-on to the line-of-sight. De Vaucouleurs and de Vaucouleurs (1964) list its classification as SB(s)cd and its optical dimensions as 17’ x 3’ arc. It is of particular interest because 18 cm OH and 6 cm H2CO absorption has been detected (Whiteoak and Gardner 1973; Gardner and Whiteoak 1974) in molecular clouds in this galaxy which overlie the small-diameter radio source located near the nucleus. In reporting the detection of the OH absorption we suggested that the HI profile in the direction of the nucleus was affected by HI absorption. In this paper we describe a study of the HI distribution which substantiates this conclusion.

Observations of CO emission (Kutner et al. 1977) have delineated a molecular cloud extending over several square degrees in the Orion region, and extensive surveys have been made of several other molecules (e.g. CN, CS, HCN, H2CO, H2H+) in the densest regions of this cloud.

The 4-m radio telescope of the CSIRO Division of Radiophysics at Epping is being used to survey the line emission associated with the 1→0 transition of CO (rest frequency 115.271 GHz) in the southern Milky Way. The programme includes mapping the CO distribution across giant molecular-cloud/HII-region complexes. As a first stage the emission has been observed towards bright southern HII regions. These results will not only serve as a basis for future extensive mapping but will also provide data which is directly comparable with observations of other molecular lines that have been made towards the HII regions.

Abstract: The Australia Telescope is an advanced radio astronomy facility planned to satisfy the major research requirements of Australian scientists. The construction project, begun in 1983, is now well along the way to completion as an Australian Bicentennial activity. The civil works at the main Culgoora site are complete. The construction of the seven 22-m antennas has begun: the first will be handed over in November 1986, the last a year later. Most other areas of the project – feed construction, receiver construction, computer development etc. are on schedule.

A spectral line survey for interstellar NH3 is being carried out using the 64-m telescopes at Parkes and Tidbinbilla. Both telescopes are equipped with K-band maser receivers yielding system temperatures below 100 K. The preliminary survey is being made with the Parkes antenna (beam = 1.35 arcmin), with follow-up mapping of the more interesting sources at Tidbinbilla (beam = 0.9 arcmin). The selected sources have in general been HII regions from the H2CO surveys made at Parkes. Statistical results from initial observations of the (1, 1), (2, 2), and (3, 3) lines in the preliminary survey are presented.

Microwave line investigations have shown that several bright southern galaxies contain dense molecular clouds overlying bright radio nuclei (see e.g. Whiteoak 1978). In terms of general kinematic models of galaxies the clouds have velocities that are anomalous, being consistent with radial motions both towards and away from the nucleus. To extend our knowledge of these motions we are investigating the distribution of optical spectral lines near the nuclei of the galaxies. We present here preliminary results for NGC 4945 and 5128.

Our previous observations of the distribution of the H110α recombination line emission (rest frequency 4.87 GHz) towards Sgr A, obtained with the Parkes 64-m telescope and a 4′ .5 arc beam (Gardner and Whiteoak 1977 — to be referred to as Paper I), suggested that the emission was concentrated around the outer edge of the ‘arc’ of continuum radiation which extends 15′ arc to the north-east of the galactic nucleus.

As part of an extensive southern survey of interstellar NH3 with the Parkes 64-m radio telescope (with a beamwidth of 81 arcsec), the (1, 1), (2, 2), and (3, 3) transitions have been observed towards the galactic centre molecular cloud G1.6-0.025. The cloud has an overall size of 10 arcmin, and contains several concentrations with differing velocities. It has several features also observed in other galactic centre clouds, e.g. high optical depths and kinetic temperatures above 50 K.

The edge-on spiral galaxy NGC 5793 has been observed at frequencies of 4860 and 14940 MHz with the Very Large Array. The corresponding half-intensity beamwidths in the final maps were 0.65 × 0.40 and 0.19 × 0.11 arcsec2. The maps show a continuum source close to the optical nucleus with dimensions of ≤0.01 and 0.04 arcsec in right ascension and declination. The average spectral index is –0.6.

We have carried out a survey of the 115 GHz CO emission (J = 1→0 transition) towards the Carina nebula (NGC 3372) using the Epping 4 m radio telescope of the CSIRO Division of Radiophysics. Of all the molecules detected in the interstellar medium CO is perhaps the best tracer of molecular clouds. It is an abundant molecule (second only to H2) and its line emission at microwave frequencies occurs at relatively low excitation.

At optical wavelengths NGC 4945 is a nondescript edge-on spiral galaxy, much of which is obscured by dense dust clouds. However, at longer wavelengths a prominent nucleus is exposed which possesses both Seyfert and star-burst characteristics. Microwave observations highlight dense molecular clouds located near the nucleus. The large velocity range of these clouds lacks an adequate interpretation.

A 3 GHz maser from the Onsala Space Observatory, Sweden, is currently at Parkes on a long-term loan basis. So far, it has been used on the 64-m radio telescope for a two-week period of spectral-line observations in February 1979, providing a system sensitivity far superior to that previously available at the same frequency. The observed lines were the ground-state transitions of CH at 3264, 3335 and 3349 MHz, the 211 – 212 transition of H2CS at 3139 MHz, and the 211-212 transition of CH3CHO at 3195 MHz.

We have detected a large cold HI cloud consisting of several fragments in the region south of the Chamaeleon I dark cloud. The cold HI cloud is shown to be a future site of star formation.

We have used the Parkes 64m telescope to observe the 20 → 3−1E absorption of CH3 OH at 12.2 GHz towards 58 Galactic H II regions and dark clouds, yielding 38 detections. The results show that CH3 OH absorbing clouds have a typical optical depth of 0.25 and a column density of 8.4 × 1015 cm−2. CH3 OH absorption is often accompanied by unsaturated maser emission and is closely associated with background H II regions. CH3 OH absorption against the 2.7 K background is also observed in several dark clouds.

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).

There is a difference of opinion as to whether W33, an HII-region/molecular-cloud complex of size about 15′ arc centred near l = 12°.8, b = -0°.2 is a single object or a chance line-of-sight alignment of two complexes at completely different distances.

As part of a general investigation of interstellar clouds associated with southern HII regions we have begun a high-resolution study of the sodium D-line absorption in the directions of early-type stars that are likely to be associated with or located behind the clouds.