William D Cotton

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  • G Brunetti, S Giacintucci, R Cassano, W Lane, D Dallacasa, T Venturi +4 others
  • 2008
Clusters of galaxies are the largest gravitationally bound objects in the Universe, containing about 10 15 solar masses of hot (10 8 K) gas, galaxies and dark matter in a typical volume of about 10Mpc 3. Magnetic fields and relativistic particles are mixed with the gas as revealed by giant radio haloes, which arise from diffuse, megaparsec-scale synchrotron(More)
We present a formal comparison of the performance of algorithms used for synthesis imaging with optical/infrared long-baseline interferometers. Five different algorithms are evaluated based on their performance with simulated test data. Each set of test data is formatted in the OI-FITS format. The data are calibrated power spectra and bispectra measured(More)
The Naval Research Laboratory and the National Radio Astronomy Observatory completed implementation of a low frequency capability on the Very Large Array at 73.8 MHz in 1998. This frequency band offers unprecedented sensitivity (∼ 25 mJy beam −1) and resolution for low-frequency observations. The longest baselines in the VLA itself provide 25 ′′ resolution;(More)
Aims. To test the dust torus model for active galactic nuclei directly, we study the extent and morphology of the nuclear dust distribution in the Circinus galaxy using high resolution interferometric observations in the mid-infrared. Methods. Observations were obtained with the MIDI instrument at the Very Large Telescope Interferometer. The 21 visibility(More)
Aims. To reveal the origin of mid-infrared radiation from the core of Centaurus A, we carried out interferometric observations with the MID-infrared Interferometer (MIDI) at ESO's VLTI telescope array. Methods. Observations were obtained with four baselines between unit telescopes of the VLTI, two of them roughly along the radio axis and two orthogonal to(More)
1 We request that comments and suggestions related to the OI Exchange Format be directed to the OLBIN email list (seeformation on how to subscribe and post to the list). ABSTRACT This paper describes the OI Exchange Format, a standard for exchanging calibrated data from optical (visible/infrared) stellar interferometers. The standard is based on the(More)
The Very Large Array (VLA) Low-frequency Sky Survey (VLSS) has imaged 95% of the 3π sr of sky north of δ = −30 • at a frequency of 74 MHz (4 meter wavelength). The resolution is 80 ′′ (FWHM) throughout, and the typical RMS noise level is σ ≈ 0.1 Jy/beam. The typical point-source detection limit is 0.7 Jy/beam and so far nearly 70,000 sources have been(More)
Calibration of radio interferometric observations becomes increasingly difficult towards lower frequencies. Below ∼ 300 MHz, spatially variant refractions and propagation delays of radio waves traveling through the ionosphere cause phase rotations that can vary significantly with time, viewing direction and antenna location. In this article we present a(More)
The aim of this paper was to describe and test a social cognitive model of physical activity tailored for adolescent girls. Participants were 1518 girls (aged 13.6 ± 0.02 years) from 24 secondary schools in New South Wales, Australia. Useable accelerometer (≥10 hours day(-1) on at least 3 days) and questionnaire data were obtained from 68% of this sample (N(More)
A complete sample of 27 radio galaxies was selected from the B2 and 3CR catalogs, in order to study their properties on the milliarcsecond scale. In the Appendix of this paper we present new radio images for 12 of them. Thanks to the present data, all the sources in this sample have been imaged at mas resolution. We discuss the general results. In(More)