tEchnology AdAptivE optics
a telescope. Robo-AO costs roughly US $0.5m. A typical 1.5m telescope might be in the $3-5m range, so adding $0.5m on top of that to greatly increase its capability is, for most, Baranec feels, worth it. In addition, because the AO
system is robotic, it can monitor specific targets over time. ‘We’re finding out now that the universe doesn’t really stand still. That’s one of the hot topics in astronomy right now,’ Baranec says. ‘At the moment, telescopes just take a snapshot, which doesn’t give any idea about how entities are changing. Astronomy is starting to get into the realm where we actually need to monitor things and see how they’re changing, and what’s interesting about their dynamics.’
Robo-AO uses a lot of the same components that the larger AO telescope systems have, but they’re all off-the-shelf components to fit small telescopes. It uses a Rayleigh laser guide star, as opposed to a sodium laser to reduce cost. The Rayleigh beacon based on a UV laser can only really be used with small telescopes.
The other advantage with equipping smaller telescopes with AO is that observations can be made in the visible spectrum, as opposed to the infrared, to which most of the larger telescopes’ AO systems are constrained. The atmospheric aberrations scale with wavelength. ‘It’s very difficult, almost impossible, to do visible light correction on large telescopes right now,’ states Baranec. ‘It’s not that it’s physically impossible, it’s just that the technology isn’t quite there yet.’ However, for small telescopes, because they are measuring light travelling through less atmosphere, the AO system doesn’t have to work as hard and there is more tolerance in the system. ‘The nice thing is you can actually get visible light AO-corrected images, which in of itself is unique to smaller telescopes,’ Baranec continues, adding that it expands the spectrum and gives astronomers different ways to look at things, which makes these
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small telescope AO systems very scientifically compelling.
Robo-AO was developed over the last year and installed in April 2011, with the system fully operational in the middle of August 2011. To date it has captured images of the Blue Snowball Nebula NGC 7662 and a section of the Hercules Globular Cluster M13 showing masses of stars. With the AO system, the images are
sharp enough to see some of the features in the nebula and determine individual stars in the M13 cluster with greater clarity. ‘We have a system that works and can get these beautiful images. We’re now trying to turn this into a fully robotic system to make the observations automatically,’ says Baranec. ‘This is something that no AO system does at the moment.
Making it automated will increase the efficiency and we’ll be able to carry out an order of magnitude more observations per night than doing it manually with a team of scientists.’ The team also want to encourage
other groups to build their own systems and hopes in the future to make public the system’s software and designs so that others can take advantage of it to further science. l
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