Sky atlas from Mt John photographs

Press, Volume CXI, Issue 32803, 31 December 1971, Page 17

Sky atlas from Mt John photographs

The year 1972 will see the publication of the “Canterbury Sky Atlas” produced from plates taken at the Mount John University Observatory.

This work was begun in 1966 under the direction of C. D. Shane, a former director of the famous Lick Observatory, in California.

At that observatory, the “Lick Atlas” was produced’’ but could only reach to decli-i nation south 30 degrees.) This meant that the far southern sky was not covered so that at its inception the plan was to use the facilities at Mount John to extend the Lick Atlas to the south celestial pole. j On the “Canterbury Sky lAtlas,” each print will cover an area of 18 degrees square on a uniform scale with a limiting magnitude of 16. An issue of 200 complete maps of the southern sky from the pole to an overlap with the “Lick Atlas” is now being printed. As there are 46 regions of the sky in the area covered, a total of 9200 prints have to be published. The maps will be provided with a grid overlay which will permit the determination (of the position of any star with an accuracy of less than half a minute of arc. This will prOvide astronomers with modern maps to replace those at present in use.

Astronomers at present depend on maps which mainly were produced in the last century. Some of these fundamental maps were made before photographic methods were in use. However; the most important, known as the Franklin-Adams charts, were the first photographic map of the entire sky. Part of the work was done in Eng land and the southern haif was made in South Africa.

Under N. A. Doughty, the “Canterbury Sky Atlas,” will be a most material contribution to astronomical research, not only in New Zealand but also overseas. Within a few years, an even more detailed map of the Southern sky will be made from Chile as a counterpart of the “Palomar Atlas” of the northern sky, but this will be much more costly and its use will be restricted to those engaged on the most advanced researches.

Quasars Quasars, or quasi-stellar objects to give them their full title, have already been discussed in these notes during the last year. Because of the many problems they pose and because of the diversity of opinions concerning them, they attract a great deal of attention from astronomers. Briefly, they can be defined as star light objects, whose light is variable, and whose spectral lines show large red shifts. Usually they . are identified with radio sources, although such sources need hot be active. They exhibit infra-red and ultra-violet excesses.

At Mount John K. H. Fea I and B. McKay have begun a! photographic survey for faint] stellar sources near the! south celestial pole and hav-j ing large infra-red and ultra-' violet excesses. This will be the first stage of a study of quasars at Canterbury; a) study that is bound to attract students wishing to work on I present problems in astrophysics. Providing facilities for students to study astronomy 'and astrophysics has enabled the University of Can-’ ] terbury to not only raise the general standard of research in the country but to direct lit into more modern methods. This was clearly shown when S. Mochnacki and K. Marsh completed the first graduate degrees in these subjects. S. Mochnacki ] assisted both the Carter and I Auckland Observatories with I advancing their observational I techniques.

Flare stars

For several years, New) Zealand astronomers, both professional and amateur, have co-operated on international programmes for the observation of flare stars. These- are stars, usually dwarf, red stars, which exhibit very sudden increases in light in a matter of seconds or tens of seconds. They return to their original brightness in tens of seconds or a few minutes. Their outbursts have amounted to as much as six magnitudes but are quite unpredictable. It appears, however, that certain of these stars are much more active in some years than in others. For this reason, they have been compared to the Sun, whose activity waxes and wanes in a period of 11 years. Observations are made photographically photoelectrically, visually and with radio instruments. Early in 1972, a typical programme will be carried out. The radio instrument of the University of Otago will observe at 120 MHz. Photographic and photometric observations will be made by a network of observers in New Zealand, while in Australia the large radio, telescope at Parkes will be used on the 6cm wave length and the Culgoora Radioheliograph will make polarisation measurements at 80MHz.

These observations will provide basic data that will enable a comparison to be made between behaviour of flares at radio and optical wave lengths. P. J. Edwards, at Otago, has suggested that the galactic X-ray disc brightness might be accounted for by unresolved flare stars. His suggestion is based on an assumed similarity between solar and stellar flares. With solar flares, there is a close connection between Xray and microwave emission. This in turn points up the

) desirability of securing obser-i (vations of flare stars at all' ’wave lengths. Programmes, such as the one just menItioned, are designed for this 'purpose. New Zealand astronomers have already taken part in a programme on such ] stars in conjunction with observations from artificial i satellites.

New techniques Having colleagues at the I (universities who are prepared] (to discuss modern techniques; ’has enabled amateurs to] develop their own improved instruments. Learning largely from the experience at Mount John, modern astrographic | cameras are now in use at several places in New Zea-’ land. These are used ini

searches for hitherto-unknown variable stars and for regular patrol photos of selected areas for novae. In the same way, photo-electric observa-I tions of variable stars are! now a regular part of the! work carried out at the Auck-

land Observatory. This, too, jis being extended to other ’Places under the stimulus Iprovided by seeing what is {dope at Mount John. It was recognised at the recent annual meeting of the Royal Astronomical Society of New Zealand, in Christ-

church, that astronomy is now' capable of being developed rapidly in the country. Because of its unique geographical position, New Zealand can make worthwhile contributions to

many problems. Even more important is the fact that astronomy is in reality part of physics and that it brings to that study many challenging problems. The time is therefore ripe to attempt to reconstruct the organisation of astronomical work throughout the country into a coherent whole. To this end, the Royal Astronomical Society appointed a commission of three to investigate ways in which its own organisation can best be adjusted to meet the challenge posed by these developments.