2018 schedule

Sun 1st
11:45-12:00
Mercure Conservatory

The estimation of astronomical seeing for sites in Australia

James Irish

Member, Astronomical Society of Victoria

Large optical telescopes are preferentially sited where astronomical "seeing" is generally of the order of one arcsecond or better. This requires a site altitude of about 2,000 metres or more. Such sites are unavailable in Australia, yet professional optical astronomers in Australia have contributed beyond what might be expected from our population. Amateur astronomers used to be diffraction-limited, but the large telescopes now available to amateurs and especially to societies means that site seeing characteristics (alongside cloudiness and light pollution) are now important. Seeing varies throughout each night, but the median is a site characteristic (possibly seasonally variable). Ways to measure seeing and the data currently available for sites in Australia will be described. Ways in which amateur astronomers can contribute to ongoing measurements will be presented.

James Irish has begun a project to estimate the optical "seeing" in the northern half of Australia at sites with less cloudiness than is generally available in Victoria. He's a retired engineer, an amateur astronomer still learning the craft. His longstanding interest in atmospheric physics began with extreme flood estimation. Since it is costly to measure seeing at multiple sites over multiple nights, Jim is using modelling and climate data to refine the search for sites where the seeing may be better than predicted from altitude and latitude.