CASA, the Common Astronomy Software Applications, is the primary data processing software for the Atacama Large Millimeter/submillimeter Array (ALMA) and the Karl G. Jansky Very Large Array (VLA), and is frequently used also for other radio telescopes. The CASA software can handle data from single-dish, aperture-synthesis, and Very Long Baseline Interferometery (VLBI) telescopes. One of its core functionalities is to support the calibration and imaging pipelines for ALMA, VLA, VLA Sky Survey, and the Nobeyama 45 m telescope. This paper presents a high-level overview of the basic structure of the CASA software, as well as procedures for calibrating and imaging astronomical radio data in CASA. CASA is being developed by an international consortium of scientists and software engineers based at the National Radio Astronomy Observatory (NRAO), the European Southern Observatory, the National Astronomical Observatory of Japan, and the Joint Institute for VLBI European Research Infrastructure Consortium (JIV-ERIC), under the guidance of NRAO.
POKORNÝ MARTIN, ZACH PETR: Design, implementation and security of a typical educational laboratory computer network. Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis, 2013, LXI, No. 4, pp. 1077-1087 Computer network used for laboratory training and for diff erent types of network and security experiments represents a special environment where hazardous activities take place, which may not aff ect any production system or network. It is common that students need to have administrator privileges in this case which makes the overall security and maintenance of such a network a diffi cult task. We present our solution which has proved its usability for more than three years. First of all, four user requirements on the laboratory network are defi ned (access to educational network devices, to laboratory services, to the Internet, and administrator privileges of the end hosts), and four essential security rules are stipulated (enforceable end host security, controlled network access, level of network access according to the user privilege level, and rules for hazardous experiments), which protect the rest of the laboratory infrastructure as well as the outer university network and the Internet. The main part of the paper is dedicated to a design and implementation of these usability and security rules. We present a physical diagram of a typical laboratory network based on multiple circuits connecting end hosts to diff erent networks, and a layout of rack devices. A er that, a topological diagram of the network is described which is based on diff erent VLANs and port-based access control using the IEEE 802.1x/EAP-TLS/RADIUS authentication to achieve defi ned level of network access. In the second part of the paper, the latest innovation of our network is presented that covers a transition to the system virtualization at the end host devices -inspiration came from a similar solution deployed at the Department of Telecommunications at Brno University of Technology. This improvement enables a greater fl exibility in the end hosts maintenance and a simultaneous network access to the educational devices as well as to the Internet. In the end, a vision of a system of virtual machines preparation and automated deployment tailored for our needs is briefl y outlined. computer networks, network security, education, laboratory network, operating system virtualization Laboratory of computer networking at the Department of Informatics (Faculty of Business and Economics, Mendel University in Brno) was founded in 2009 in order to support courses specialized in computer networking, network security and operating systems taught for bachelor and master degrees, and to provide an experimental environment for fi nal thesis and for networking or security tests. The equipment of the laboratory covers basic areas in routing and switching, network security, wireless networking, VoIP, and server virtualization.User requirements, design, implementation and maintenance of an educational network dedicated to laborat...
We describe a new protocol deployed at the National Radio Astronomy Observatory’s Karl G. Jansky Very Large Array (VLA) to support the distribution of data in support of commensal data analysis. The protocol, vys, is designed to provide access to a high time resolution data stream while a primary observation continues with the typical (lower) time resolution data stream. This form of dual time resolution, commensal observing has been implemented to enable the search for millisecond astrophysical transient events by a new, dedicated compute cluster located at the VLA. The fast transient detection system, realfast, performs real-time analysis in situ to detect events of interest and record relatively short duration data “cut-outs” of those events. By selectively recording high time resolution data, provided by vys at rates of up to 1.4[Formula: see text]GB[Formula: see text]s[Formula: see text], realfast will reduce the recorded data volume by an estimated factor of up to 1000. This makes it possible to search for transients commensally in a high data rate stream over the thousands of hours needed to find the rarest events.
We present the first blind interferometric detection and imaging of a millisecond radio transient with an observation of transient pulsar J0628+0909. We developed a special observing mode of the Karl G. Jansky Very Large Array (VLA) to produce correlated data products (i.e., visibilities and images) on a time scale of 10 ms. Correlated data effectively produce thousands of beams on the sky that can localize sources anywhere over a wide field of view. We used this new observing mode to find and image pulses from the rotating radio transient (RRAT) J0628+0909, improving its localization by two orders of magnitude. Since the location of the RRAT was only approximately known when first observed, we searched for transients using a wide-field detection algorithm based on the bispectrum, an interferometric closure quantity. Over 16 minutes of observing, this algorithm detected one transient offset roughly 1 ′ from its nominal location; this allowed us to image the RRAT to localize it with an accuracy of 1. ′′ 6. With a priori knowledge of the RRAT location, a traditional beamforming search of the same data found two, lower significance pulses. The refined RRAT position excludes all potential multiwavelength counterparts, limiting its optical luminosity to L i ′ < 1.1 × 10 31 erg s −1 and excluding its association with a young, luminous neutron star.
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