A talk on solar astronomy in H-alpha
by Harry Roberts
Harry Roberts is to give his talk to Shoalhaven Astronomers on 18th May
The speaker began study of the sun in H-alpha on June 23, 2001. Within minutes the filter revealed prominences and surface filaments; then a small but brilliant flare erupted. It was a “revelation”!
Yet the peak of flaring for Solar Cycle 23 still lay two and a half years in the future, and flaring would be sustained well into 2007. Over that time hundreds of flares and ejection events would be logged in an extraordinary adventure of daytime astronomy.
The flaring of SC23 was probably the strongest for a century – and was followed, unexpectedly, by the deepest minimum for a century – prompting NASA to denounce the sun for “behaving unpredictably”!
Solar cycle SC24 is now well advanced, and GOES Class X flares (the strongest) erupted early in 2011; so activity is increasing. This, together with the fact that H-alpha equipment has never been cheaper, means that right now is the ideal time to enter the bizarre world of H-alpha astronomy. There is more to be seen than you’d dare imagine.
The Talk will cover:
Making a start: equipment and techniques.
Some H-alpha features and how to recognise them.
The coming maximum, what to expect.
Solar magnetism and the reversal of polar fields.
And much more.
Astronomical Bio: Harry Roberts
Growing up in Adelaide during the 1950’s and 60’s, a time of intense solar activity, Harry has the sun “in his veins”.
His first sun images were projected with a small ‘scope, and then a larger reflector in the 1960’s, with regular viewing over following decades.
In 2000 he began daily recording of sunspots in white-light. In 2001 he upgraded his 8” ‘scope by fitting an H-alpha filter, taking his first steps into the bizarre world of high temperature plasmas, flares and ejections.
Observing in Sydney (often all day) he found that such events happen many times daily during solar maximum – and has since then recorded hundreds of flares and associated events.
In 2006 he adapted a freeware product to pin-point H-alpha transients on the sun– a crucial tool for serious research.
These efforts led to many articles in amateur journals as well as presentations to amateur groups and public gatherings.
His favourite astronomical moment was following an ejecting filament from the sun’s surface to a point in space more than one solar radius away; material shown to be moving at ~300 km.sec-1!
Affiliations: Sydney City Skywatchers, the Astronomical Society of NSW, the Royal Astronomical Society of NZ and the Astronomical Society of Coonabarabran.
Objective: to better communicate the dramatic and paradoxical character of our star and its high velocity transients.
Awards: ASNSW Southern Cross Award 2003, ASNSW Editor’s Award 2003, NACAA poster prize 2008 (“Anomalous Flaring in Cycle 23”), and the ASNSW Mike Kerr Medal 2009 for Observational
Astronomy (inaugural award).