2010 programme

Sat 3rd
15:30-16:00

A Mathematical Model to Predict the Resolution of Double Stars by Amateurs and their Telescopes

Dr Tim Napier-Munn

Astronomical Association of Queensland

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.

Tim Napier-Munn

Tim’s interest in astronomy goes back to his childhood, but he has been a serious observer (off and on) for about 25 years. He has an 8” SCT which travels, and a 14” SCT which is permanently housed in a Sirius dome in the back garden of his home in Brisbane. He’s not sure why he is obsessed with double stars but it may be the challenge of splitting difficult pairs whilst the seeing, advancing years and the stars themselves conspire against him. His joint interests in double stars and statistics spawned the AAQ project to be presented at NACAA XXIV. He is the founding Director of the AAQ Double Star Section which is currently conducting a programme on the measurement of neglected southern doubles using imaging.