New Zealand

In the southern hemisphere, very few observers are active, even though there are many underobserved systems. One exception is Ormond Warren whose interest began in primary school when the headmaster allowed him to use his 3-inch refractor.

In 1987 he became interested in double star astronomy after moving to Wanganui, where he found the city observatory had a fine history in this field. His first study was the set of pairs and triples originally discovered at this site, early last century, and given the discovery designation NZO. Fortunately he was able to use the famous 23-cm f/15 Fletcher equatorial (by Cooke the Elder, 1860) (Figure 20.9) and an antique Cooke & Sons Type-A (English) bifilar micrometer, the same instruments used by the discoverers. By 1990 this project expanded to a general survey of southern hemisphere pairs and multiples.

Figure 20.9. The

Fletcher equatorial at the Ward Observatory, Wanganui. Reproduced by kind permission of Wanganui Astronomical Society.

Figure 20.9. The

Fletcher equatorial at the Ward Observatory, Wanganui. Reproduced by kind permission of Wanganui Astronomical Society.

Currently he is a planetarium presenter at the Stardome Observatory and Planetarium in Auckland city, where he also undertakes a measuring programme. His most recent papers were published in the Royal Astronomical Society of New Zealand (RASNZ) journal Southern Stars in 2000 (two) and 2001 (one). Ormond is acting as Observation Coordinator and has produced a number of guides to various aspects of observing. In addition he has produced a number of lists of pairs which need to be observed for signs of change in relative position since last measured. Some effort has been made to scrutinise and make approximate measures of these pairs. Many of them have been measured only once (at discovery), and hence confirming observations are necessary. About 30% of those checked so far have been found to be discordant with the data in the Washington Catalogue of Visual Double Stars (WDS). These "anomalies" are being compiled into a list for further study: they involve pairs with erroneous positions, erroneous magnitudes perhaps due to variability, and some which at present cannot yet be identified in a field with other nearby pairs. Some of the pairs have changed to such a degree that mere visual scrutiny would alert the observer to the fact that motion had taken place. In most of these cases one of the stars involved has a relatively high proper motion rather than the pair being a true binary.

The Double Star Section of the RASNZ was formed in April 2000 and is currently headed by the Director, Warren Kissling. Its purpose is to observe and measure doubles in the southern hemisphere, many of which suffer from a lack of regular observation. Two of the members of the section have RETEL micrometers and are learning how to make useful measures with them.

Of particular interest are the NZO pairs, already mentioned. Another member, comet discoverer Rod Austin, has been working to produce a definitive set of these pairs that Ormond Warren and he have worked on over the past 10 years or so.

One of the main problems for the future may well be to encourage more observers to take on a serious programme of measurement, but one advantage of being in New Zealand is access to relatively clear, dark and (in terms of double-star work) neglected skies. There is, however, a dearth of measuring equipment which, partly due to the low exchange rate for NZ dollars, tends to be very expensive.

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