3,178 research outputs found
The Science Case for PILOT I: Summary and Overview
Original article can be found at: http://www.publish.csiro.au/?nid=139&aid=108 DOI: 10.1071/AS08048 [Open access article]PILOT (the Pathfinder for an International Large Optical Telescope) is a proposed 2.5-m optical/infrared telescope to be located at Dome C on the Antarctic plateau. Conditions at Dome C are known to be exceptional for astronomy. The seeing (above ∼30 m height), coherence time, and isoplanatic angle are all twice as good as at typical mid-latitude sites, while the water-vapour column, and the atmosphere and telescope thermal emission are all an order of magnitude better. These conditions enable a unique scientific capability for PILOT, which is addressed in this series of papers. The current paper presents an overview of the optical and instrumentation suite for PILOT and its expected performance, a summary of the key science goals and observational approach for the facility, a discussion of the synergies between the science goals for PILOT and other telescopes, and a discussion of the future of Antarctic astronomy. Paper II and Paper III present details of the science projects divided, respectively, between the distant Universe (i.e. studies of first light, and the assembly and evolution of structure) and the nearby Universe (i.e. studies of Local Group galaxies, the Milky Way, and the Solar System).Peer reviewe
Stellar intensity interferometry over kilometer baselines: Laboratory simulation of observations with the Cherenkov Telescope Array
A long-held astronomical vision is to realize diffraction-limited optical
aperture synthesis over kilometer baselines. This will enable imaging of
stellar surfaces and their environments, show their evolution over time, and
reveal interactions of stellar winds and gas flows in binary star systems. An
opportunity is now opening up with the large telescope arrays primarily erected
for measuring Cherenkov light in air induced by gamma rays. With suitable
software, such telescopes could be electronically connected and used also for
intensity interferometry. With no optical connection between the telescopes,
the error budget is set by the electronic time resolution of a few nanoseconds.
Corresponding light-travel distances are on the order of one meter, making the
method practically insensitive to atmospheric turbulence or optical
imperfections, permitting both very long baselines and observing at short
optical wavelengths. Theoretical modeling has shown how stellar surface images
can be retrieved from such observations and here we report on experimental
simulations. In an optical laboratory, artificial stars (single and double,
round and elliptic) are observed by an array of telescopes. Using high-speed
photon-counting solid-state detectors and real-time electronics, intensity
fluctuations are cross correlated between up to a hundred baselines between
pairs of telescopes, producing maps of the second-order spatial coherence
across the interferometric Fourier-transform plane. These experiments serve to
verify the concepts and to optimize the instrumentation and observing
procedures for future observations with (in particular) CTA, the Cherenkov
Telescope Array, aiming at order-of-magnitude improvements of the angular
resolution in optical astronomy.Comment: 18 pages, 11 figures; Presented at SPIE conference on Astronomical
Telescopes + Instrumentation in Montreal, Quebec, Canada, June 2014. To
appear in SPIE Proc.9146, Optical and Infrared Interferometry IV
(J.K.Rajagopal, M.J.Creech-Eakman, F.Malbet, eds.), 201
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