4,017 research outputs found

    A radio continuum survey of the southern sky at 1420 MHz. Observations and data reduction

    Get PDF
    We describe the equipment, observational method and reduction procedure of an absolutely calibrated radio continuum survey of the South Celestial Hemisphere at a frequency of 1420 MHz. These observations cover the area 0h < R.A. < 24h for declinations less than -10 degree. The sensitivity is about 50 mK T_B (full beam brightness) and the angular resolution (HPBW) is 35.4', which matches the existing northern sky survey at the same frequency.Comment: 9 pages with 9 figures, A&A, in pres

    Reports on Payments to Governments: A critical review of early developments and experiences

    Get PDF
    We are concerned to review and discuss aspects of the Reports submitted in line with the Payments to Governments Regulations. We consider the process of transposition of this EU Accounting Law into UK law and the early implementation or operationalization of this law in the UK. Recommendations drawn from the study are intended to be of use to a variety of stakeholders who may input into the upcoming government consultation on these regulations. This version was published by Robert Gordon University

    Spectral Index of the Diffuse Radio Background Measured From 100 to 200 MHz

    Get PDF
    The mean absolute brightness temperature of the diffuse radio background was measured as a function of frequency in a continuous band between 100 and 200 MHz over an effective solid angle of ~pi str at high Galactic latitude. A spectral brightness temperature index of beta = 2.5 +/- 0.1 (alpha_s = 0.5) was derived from the observations, where the error limits are 3-sigma and include estimates of the instrumental systematics. Zenith drift scans with central declinations of -26.5 degrees and spanning right ascensions 0 to 10 hours yielded little variation in the mean spectral index. The mean absolute brightness temperature at 150 MHz was found to reach a minimum of T = 237 +/- 10 K at a right ascension of 2.5 hours. Combining these measurements with those of Haslam et al. 1982 yields a spectral index of beta = 2.52 +/- 0.04 between 150 and 408 MHz.Comment: 8 pages including 7 figures and 4 tables. Accepted by A

    The On The Fly Imaging Technique

    Full text link
    The On-The-Fly (OTF) imaging technique enables single-dish radio telescopes to construct images of small areas of the sky with greater efficiency and accuracy. This paper describes the practical application of the OTF imaging technique. By way of example the implementation of the OTF imaging technique at the NRAO 12 Meter Telescope is described. Specific requirements for data sampling, image formation, and Doppler correction are discussed.Comment: 10 pages, 13 figures, accepted A&

    Does tiny-scale atomic structure exist in the interstellar medium ?

    Full text link
    We report on preliminary results from the recent multi-epoch neutral hydrogen absorption measurements toward three pulsars, B0823+26, B1133+16 and B2016+28, using the Arecibo telescope. We do not find significant variations in optical depth profiles over periods of 0.3 and 9--10 yr, or on spatial scales of 10--20 and 70--85 AU. The large number of non detections of the tiny scale atomic structure suggests that the AU-sized structure is not ubiquitous in the interstellar medium and could be quite a rare phenomenon.Comment: Accepted by ApJ Letters, 5 pages, 2 figure

    DASI Three-Year Cosmic Microwave Background Polarization Results

    Full text link
    We present the analysis of the complete 3-year data set obtained with the Degree Angular Scale Interferometer (DASI) polarization experiment, operating from the Amundsen-Scott South Pole research station. Additional data obtained at the end of the 2002 Austral winter and throughout the 2003 season were added to the data from which the first detection of polarization of the cosmic microwave background radiation was reported. The analysis of the combined data supports, with increased statistical power, all of the conclusions drawn from the initial data set. In particular, the detection of E-mode polarization is increased to 6.3 sigma confidence level, TE cross-polarization is detected at 2.9 sigma, and B-mode polarization is consistent with zero, with an upper limit well below the level of the detected E-mode polarization. The results are in excellent agreement with the predictions of the cosmological model that has emerged from CMB temperature measurements. The analysis also demonstrates that contamination of the data by known sources of foreground emission is insignificant.Comment: 13 pages Latex, 10 figures, submitted to Ap

    Acoustic emission monitoring of a soil slope: comparisons with continuous deformation measurements

    Get PDF
    Acoustic emission (AE) has become an established approach to monitor the stability of soil slopes. However, the challenge has been to develop strategies to interpret and quantify deformation behaviour from the measured AE. This paper presents the first comparison of continuous AE (measured using an active waveguide) and continuous subsurface deformation measurements. The active waveguide is installed in a borehole through a slope and comprises a metal waveguide rod or tube with a granular backfill surround. When the host slope deforms, the column of granular backfill also deforms, generating AE that can propagate along the waveguide. This paper presents results from a field trial at a reactivated soil slope in North Yorkshire, UK. The measurements confirm that AE rates generated are directly proportional to the velocity of slope movement (e.g. the AE rate versus velocity relationship determined for a series of slope movement events produced an R 2 value of 0·8) and demonstrate the performance of AE monitoring of active waveguides to provide continuous information on slope displacements and displacement rates with high temporal resolution

    Accounting Law in Practice: Compliance, Consistency and Substance Focusing on the UK’s Implementation of EU Extractive Industry Country by Country Reporting of Government Payments to Governments

    Get PDF
    The passing into EU Law of a requirement that all companies domiciled in member states or listed on EU stock exchanges should publish a Report of Payments to Governments on the face of it is a victory for the civil society organizations long campaigning for the attendant increased transparency and accountability, a step towards better conditions and possibilities for many of the world’s poor. But it cannot be taken for granted. It was passed with a condition that it be reviewed (at both member state level, where a review can feed into the federal level review, and at the level of the EU), which is an opportunity to better it or a threat to reverse positive potentialities. The UK Brexit vote adds some uncertainty regarding the future of the law in the UK. And studies of manifestations of practices such as accounting and auditing (often intersecting with the law) caution against too much optimism as to their straightforward effectiveness. With a view to understanding this particular law in practice, so that it be strengthened and better function in line with its intended aims, we explore processes of its construction and early adoption in the UK. In a preliminary analysis, we elaborate how interpretations of the Law within the Extractives Industry run counter to the spirit or substance of the law and give rise to different and apparently problematic translations of the law into practice. Reflecting on our analysis, we make some recommendations as to ways forward

    Probing Cosmic Strings with Satellite CMB measurements

    Full text link
    We study the problem of searching for cosmic string signal patterns in the present high resolution and high sensitivity observations of the Cosmic Microwave Background (CMB). This article discusses a technique capable of recognizing Kaiser-Stebbins effect signatures in total intensity anisotropy maps, and shows that the biggest factor that produces confusion is represented by the acoustic oscillation features of the scale comparable to the size of horizon at recombination. Simulations show that the distribution of null signals for pure Gaussian maps converges to a χ2\chi^2 distribution, with detectability threshold corresponding to a string induced step signal with an amplitude of about 100 \muK which corresponds to a limit of roughly Gμ<1.5×106G\mu < 1.5\times 10^{-6}. We study the statistics of spurious detections caused by extra-Galactic and Galactic foregrounds. For diffuse Galactic foregrounds, which represents the dominant source of contamination, we derive sky masks outlining the available region of the sky where the Galactic confusion is sub-dominant, specializing our analysis to the case represented by the frequency coverage and nominal sensitivity and resolution of the Planck experiment.Comment: 14 pages, 3 figures, to be published in JCA

    Reports on Payments to Governments: A report on early developments and experiences

    Get PDF
    We are concerned in this report to review and discuss aspects of the Reports submitted in line with the Payments to Governments Regulations. We consider the process of transposition of this Accounting Law into UK law and the early implementation or operationalization of this law in the UK. Recommendations drawn from the study will be useful for Publish What You Pay (PWYP) and other interested stakeholders in communications with government, regulators and standard setters and in general campaign activity
    corecore