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TOPIC: Long Wavelength Array (LWA)
Blobrana


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RE: Long Wavelength Array (LWA)
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Title: First Light for the First Station of the Long Wavelength Array
Authors: G. B. Taylor, S. W. Ellingson, N. E. Kassim, J. Craig, J. Dowell, C. N. Wolfe, J. Hartman, G. Bernardi, T. Clarke, A. Cohen, N. P. Dalal, W. C. Erickson, B. Hicks, L. J. Greenhill, B. Jacoby, W. Lane, J. Lazio, D. Mitchell, R. Navarro, S. M. Ord, Y. Pihlstrom, E. Polisensky, P. S. Ray, L. J. Rickard, F. K. Schinzel, H. Schmitt, E. Sigman, M. Soriano, K. P. Stewart, K. Stovall, S. Tremblay, D. Wang, K. W. Weiler, S. White, D. L. Wood

The first station of the Long Wavelength Array (LWA1) was completed in April 2011 and is currently performing observations resulting from its first call for proposals in addition to a continuing program of commissioning and characterisation observations. The instrument consists of 258 dual-polarization dipoles, which are digitised and combined into beams. Four independently-steerable dual-polarization beams are available, each with two "tunings" of 16 MHz bandwidth that can be independently tuned to any frequency between 10 MHz and 88 MHz. The system equivalent flux density for zenith pointing is ~3 kJy and is approximately independent of frequency; this corresponds to a sensitivity of ~5 Jy/beam (5sigma, 1 s); making it one of the most sensitive meter-wavelength radio telescopes. LWA1 also has two "transient buffer" modes which allow coherent recording from all dipoles simultaneously, providing instantaneous all-sky field of view. LWA1 provides versatile and unique new capabilities for Galactic science, pulsar science, solar and planetary science, space weather, cosmology, and searches for astrophysical transients. Results from LWA1 will detect or tightly constrain the presence of hot Jupiters within 50 parsecs of Earth. LWA1 will provide excellent resolution in frequency and in time to examine phenomena such as solar bursts, and pulsars over a 4:1 frequency range that includes the poorly understood turnover and steep-spectrum regimes. Observations to date have proven LWA1's potential for pulsar observing, and just a few seconds with the completed 256-dipole LWA1 provide the most sensitive images of the sky at 23 MHz obtained yet. We are operating LWA1 as an open skies radio observatory, offering ~2000 beam-hours per year to the general community.

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Blobrana


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Title: The LWA1 Radio Telescope
Authors: S.W. Ellingson, G.B. Taylor, J. Craig, J. Hartman, J. Dowell, C.N. Wolfe, T.E. Clarke, B.C. Hicks, N.E. Kassim, P.S. Ray, L.J Rickard, F.K. Schinzel, K.W. Weiler

LWA1 is a new radio telescope operating in the frequency range 10-88 MHz, located in central New Mexico. The telescope consists of 258 pairs of dipole-type antennas whose outputs are individually digitised and formed into beams. Simultaneously, signals from all dipoles can be recorded using one of the instrument's "all dipoles" modes, facilitating all-sky imaging. Notable features of the instrument include high intrinsic sensitivity (about 6 kJy zenith system equivalent flux density), large instantaneous bandwidth (up to 78 MHz), and 4 independently-steerable beams utilising digital "true time delay" beamforming. This paper summarises the design of LWA1 and its performance as determined in commissioning experiments. We describe the method currently in use for array calibration, and report on measurements of sensitivity and beamwidth.

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LWA-1 station
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An innovative new radio telescope array under construction in central New Mexico will eventually harness the power of more than 13,000 antennas and provide a fresh eye to the sky. The antennas, which resemble droopy ceiling fans, form the Long Wavelength Array, designed to survey the sky from horizon to horizon over a wide range of frequencies.
The University of New Mexico leads the project, and NASA's Jet Propulsion Laboratory, Pasadena, Calif., provides the advanced digital electronic systems, which represent a major component of the observatory.
The first station in the Long Wavelength Array, with 256 antennas, is scheduled to start surveying the sky by this summer. When complete, the Long Wavelength Array will consist of 53 stations, with a total of 13,000 antennas strategically placed in an area nearly 400 kilometres in diameter. The antennas will provide sensitive, high-resolution images of a region of the sky hundreds of times larger than the full moon. These images could reveal radio waves coming from planets outside our solar system, and thus would turn out to be a new way to detect these worlds. In addition to planets, the telescope will pick up a host of other cosmic phenomena.
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Long Wavelength Demonstrator Array
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Scientists Make First Discovery Using Revolutionary Long Wavelength Demonstrator Array
Scientists from NRL's Space Science and Remote Sensing Divisions, in collaboration with researchers from the University of New Mexico (UNM) and the National Radio Astronomy Observatory (NRAO) located in Socorro, N.M., have generated the first scientific results from the Long Wavelength Demonstrator Array (LWDA). The measurements were obtained during field tests and calibration of two prototype antennas for the much larger Long Wavelength Array (LWA), which will eventually consist of nearly 13,000 similar antennas.
Utilising radio emissions from the approximately 300 year-old Cassiopeia A (Cas A) supernova remnant (SNR) - one of the brightest astronomical radio sources in the sky - to establish baseline measurements, NRL scientist and National Research Council (NRC) postdoctoral fellow Dr. Jake Hartman utilised the LWDA to confirm and extend a study initiated by fellow NRL-NRC postdoc Dr. Joseph Helmboldt.

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Commissioning observations made in October 2006 by the Long Wavelength Demonstrator Array (LWDA) highlight its all sky imaging capability. This 24 hour movie is made at a frequency of 73.8 MHz and shows the full sky as visible from the LWDA site in New Mexico. As the sky rotates, emission from the bright sources Cassiopeia A, Cygnus A, and the Sun, as well as the bright regions of the Galactic Plane, are all clearly visible. The Galactic Center region is marked by the position of the Sagittarius A complex. This movie was made by Tracy Clarke (NRL/Interferometrics Inc) using AIPS to process the observations from the LWDA

LWDA All Sky Imaging



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Long Wavelength Array (LWA)
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Astronomers at the Naval Research Laboratory (NRL) have produced the first images of the sky as seen by a prototype of the Long Wavelength Array (LWA), a revolutionary new radio telescope to be constructed in southwestern New Mexico. The images show emissions from the center of our Galaxy, a supermassive black hole, and the remnant of a star that exploded in a supernova over 300 years ago.
Not only a milestone in the development of the LWA, the images are also a first glimpse through a new window on the cosmos. First light is an astronomical term for the first image produced with a telescope. It is a key milestone for any telescope because it indicates that all of the individual components are working in unison as planned.
The University of New Mexico, the lead institution for the LWA, will supervise all aspects of its siting, design, construction and operation, says Greg Taylor, Interim Director for the LWA and associate professor of Physics and Astronomy at UNM.

070LWA

Commissioned observations made by the LWDA show its all sky imaging capability. In this image from the LWDA first light movie, emission from the bright sources Sagittarius A at the centre of our galaxy, Cassiopeia A, and the black-hole powered radio galaxy, Cygnus A, are all clearly visible. Cassiopeia A, the strongest discrete radio source visible in the sky, is a remnant of a massive star that exploded in a supernova over 300 years ago.
Credit: Tracy Clarke, Interferometrics, Inc.

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