Talk

Continuing the successful observing program reported at the 2nd Trans Tasman Symposium on Occultations (NACAA XXIII), Team Occultation has had another series of well observed lunar grazing occultations over the past two years. The number of expeditions organised, the number of attending observers, the total distance travelled to the sites and the tally of events observed have increased since the last report. The discovery of a hitherto unknown double star is a bonus to our observing programme.
Team Occultation is always willing to accept new recruits. You would be most welcome!

January 27th 2010 commemorates 150 years since the death of Sir Thomas Brisbane. Although the Parramatta Observatory was in operation by May 1822, several current non-Australian astronomy texts credit the astronomical research of the Southern Hemisphere during the early nineteenth century to South Africa. The few published exceptions that mention Sir Thomas and Parramatta Observatory include a number of persistent inaccuracies.
Examples of information errors highlight the importance of individual research. Comparing in-text statements and published references with primary-source documents show obvious mistakes. Compounding this misinformation is the ease of access to the World Wide Web where a posting of inaccurate, ill-researched information becomes an accepted fact.
Appropriate recognition of Sir Thomas's observatory, functioning under the constraints of scientific isolation, is long overdue. The grandeur of this endeavour is important to Australia and our astronomical and scientific history. The vagaries of history, the loss of written records, misinformation, written and verbal embellishment, and time, have obscured the richness that was Parramatta Observatory.
The pursuit of accurate records may lift the shroud of anonymity and justly unveil the achievements of Sir Thomas Brisbane and the extraordinary individuals of Parramatta Observatory.

On the 22nd June 2008 Pluto and Charon occulted the star 2UCAC 25370733, a magnitude 12.4 star in north western Sagittarius. This event would give observers from Australia to South Africa an opportunity to observe events involving Pluto and Charon occulting the same star.
Weather played an important role in determining success of the observation but seven observers managed to dodge the clouds to record positive events for Pluto and one observer on Réunion Island observed a positive event for Charon. This twin occultation is the first ever recorded for Pluto and Charon.
These successes enabled the characteristics of Pluto’s atmosphere and the Pluto-Charon orbits to be refined.
This presentation will discuss observation techniques and will show what is now known about Pluto’s atmosphere and discuss updates to the Pluto-Charon ephemerides.

Thomas Digges and Thomas Harriot were highly respected astronomers during the intellectual renaissance in England, on par with their better-known peers: Dee, Harvey, Gilbert and Galileo. However, today neither Digges nor Harriot are well known by the general public. A number of unfortunate incidents and circumstances resulted in both astronomers having to wait for several hundred years before their work became known to a wider audience. Digges’s contribution to the introduction of Copernican cosmology is often credited to the Dominican monk, Giordano Bruno. However Digges published the ideas of Copernicus in English and introduced the idea of an infinite universe in 1576, well before Bruno’s visit to England.
Harriot’s work was lost for several hundred years due to his reluctance to publish, and the inability of the executors of his will to adequately publish his work. His reasons not to publish are discussed, along with the discovery of his prior claim to be the first person to view the moon through a telescope. The likelihood of the involvement of Digges and Harriot in the development of an ‘Elizabethan telescope’, in the late 1570s is discussed.

Although the theory of optical resolution is well established, there are relatively few criteria for predicting the purest form of astronomical resolution, the ability to resolve or "split" a double star. The best known is Dawes’ criterion for the resolution of two 6th magnitude stars of known separation based only on the telescope aperture.
The Astronomical Association of Queensland has therefore conducted a project to develop a statistical model to predict the probability of resolving a double star given the telescope aperture, the separation and magnitudes of the stars, and the estimated seeing. The model is based on observations made by 16 members of the AAQ using 25 different telescopes in the aperture range 80 – 508mm. 334 observations were made of 46 different doubles. A further 55 independent observations of 10 different doubles were then made by four of the observers using 6 telescopes to validate the predictions of the model. A spreadsheet is available which allows easy use of the model to predict splits. Experience suggests that the model provides credible predictions.
Models of this kind benefit from more data, and any observer can easily contribute observations to allow the model to be improved.

2010 marks forty years since I attended my first NACAA in Wollongong. But rather than reflect on the past, this presentation will talk about the impact of the Internet on the operation of NACAA Inc, and will look to its future.
The formation of NACAA Inc in 2006 has radically changed the way NACAA is structured. The organising committees are now widely distributed across the country, rather than a group that can easily meet face-to-face. Since its inception, NACAA Inc. has relied on the use of on-line technologies, particularly mailing lists and the Web, to organise its activities. The full potential of these technologies haven't been reached yet, due to various problems. One example is the lack of contributions from the NACAA community -- I hope this presentation will encourage at least a few listeners to contribute their memorabilia. Some of the other problems will be outlined during the talk.
As well, I will present my thoughts on the impact of the on-line age on the future of NACAA: an increasing reliance on our web site for many functions, recording presentations for download to increase public awareness of what NACAA does, the need for on-line technologies (and on-line savvy people) to coordinate the event, the problems involved in web-casting the event, and other issues.

A revolution is quietly taking place in planetary imaging by amateurs, with a new breed of digital video cameras and computers allowing extremely high resolution images to be obtained of the bright planets (Jupiter, Saturn and Mars). This talk will outline some of the advances in both equipment and techniques that have become popular in the last several years and are resulting in images that show detail down to the resolving limit of the instrument.

The observation and study of variable stars is uniquely tied to stellar evolution. Over time observers can gain a rare perspective into the lives of stars; not, as is usual, from books alone, but through the telescope. From inconstant newborn stars, to old stars ponderously shaking off their envelopes, and exotic binary systems, the observations of variable star observers are used by astronomers to probe the nature of stars.
This presentation gives some examples of real time stellar evolution, including some really spectacular events, and describes how and why to get involved in this most rewarding field.

Supergiant stars, such as the blue supergiant Eta Carinae with a mass equal to 120 suns, release nuclear energy as star light as they progressively fuse hydrogen into helium, carbon, oxygen, neon and silicon. When the silicon core reaches 3500 million degrees Kelvin it collapses in only a few months. It then just takes a couple of days to form an unstable core of nickel and iron, with a mass of nearly 2 suns, before exploding as a supernova. The chemical nuclei are produced in the burning shells and core of each supergiant star. On the basis of detailed research a consistent set of nuclear models of these nuclei is proposed as an extension to those models discussed at previous NACAAs. The models are simple and the author does not know of any other structural nuclear models, unlike the situation in atomic and molecular physics.

There are several very good software packages available to allow the reduction of images from CCD for photometric and astrometric analysis. But imagine the convenience of integrating such a solution into a robotic observatory. In this follow up to the earlier session Robotic Research for the Amateur Astronomer, the presenter will discuss this interesting method for working with data.