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We present the third data release from the Parkes Pulsar Timing Array (PPTA) project. The release contains observations of 32 pulsars obtained using the 64-m Parkes ‘Murriyang’ radio telescope. The data span is up to 18 yr with a typical cadence of 3 weeks. This data release is formed by combining an updated version of our second data release with $\sim$3 yr of more recent data primarily obtained using an ultra-wide-bandwidth receiver system that operates between 704 and 4032 MHz. We provide calibrated pulse profiles, flux density dynamic spectra, pulse times of arrival, and initial pulsar timing models. We describe methods for processing such wide-bandwidth observations and compare this data release with our previous release.
We describe 14 yr of public data from the Parkes Pulsar Timing Array (PPTA), an ongoing project that is producing precise measurements of pulse times of arrival from 26 millisecond pulsars using the 64-m Parkes radio telescope with a cadence of approximately 3 weeks in three observing bands. A comprehensive description of the pulsar observing systems employed at the telescope since 2004 is provided, including the calibration methodology and an analysis of the stability of system components. We attempt to provide full accounting of the reduction from the raw measured Stokes parameters to pulse times of arrival to aid third parties in reproducing our results. This conversion is encapsulated in a processing pipeline designed to track provenance. Our data products include pulse times of arrival for each of the pulsars along with an initial set of pulsar parameters and noise models. The calibrated pulse profiles and timing template profiles are also available. These data represent almost 21 000 h of recorded data spanning over 14 yr. After accounting for processes that induce time-correlated noise, 22 of the pulsars have weighted root-mean-square timing residuals of
in at least one radio band. The data should allow end users to quickly undertake their own gravitational wave analyses, for example, without having to understand the intricacies of pulsar polarisation calibration or attain a mastery of radio frequency interference mitigation as is required when analysing raw data files.
We describe an ultra-wide-bandwidth, low-frequency receiver recently installed on the Parkes radio telescope. The receiver system provides continuous frequency coverage from 704 to 4032 MHz. For much of the band (
), the system temperature is approximately 22 K and the receiver system remains in a linear regime even in the presence of strong mobile phone transmissions. We discuss the scientific and technical aspects of the new receiver, including its astronomical objectives, as well as the feed, receiver, digitiser, and signal processor design. We describe the pipeline routines that form the archive-ready data products and how those data files can be accessed from the archives. The system performance is quantified, including the system noise and linearity, beam shape, antenna efficiency, polarisation calibration, and timing stability.
The goal of the division is to address the scientific issues that were developed at the 2009 IAU General Assembly in Rio de Janeiro. These are:
• Astronomical constants
—Gaussian gravitational constant, Astronomical Unit, GMSun, geodesic precession-nutation
• Astronomical software
• Solar System Ephemerides
—Comparison of dynamical reference frames
• Future Optical Reference Frame
• Future Radio Reference Frame
• Predictions of Earth orientation
• Units of measurements for astronomical quantities in relativistic context
• Astronomical units in the relativistic framework
• Time-dependent ecliptic in the GCRS
• Asteroid masses
• Review of space missions
• Detection of gravitational waves
• VLBI on the Moon
• Real time electronic access to UT1-UTC
In pursuit of these goals Division I members have made significant scientific and organizational progress, and are organizing a Joint Discussion on Space-Time Reference Systems for Future Research at the 2012 IAU General Assembly. The details of Division activities and references are provided in the individual Commission and Working Group reports in this volume. A comprehensive list of references related to the work of the Division is available at the IAU Division I website at http://maia.usno.navy.mil/iaudiv1/.
There were four 1.5-hour sessions of Division I business meetings during the XXVIIth IAU General Assembly. The first three were devoted to the reports of Commissions, Working Groups and services associated with the Division, discussion about plans for the next triennium and future structure of the Division. Scientific presentations on the future space astrometric mission Gaia were made at the fourth session.
The realization and dissemination of the international time scales is the responsibility of the section on Time, Frequency and Gravimetry of the BIPM. Commission 31 supports and coordinates investigations associated with Time definitions, realizations, astronomical data relevant to atomic timekeeping, such as pulsar data. The major developments achieved during the period 2005-2008 in that domain are reported here.
Division I provides a focus for astronomers studying a wide range of problems related to fundamental physical phenomena such as time, the inertial reference frame, positions and proper motions of celestial objects and precise dynamical computation of the motions of bodies in stellar or planetary systems in the Universe.
Although Very Long Baseline Interferometry has resolved a few binary stellar systems, pulsars provide the main source of binary and multiple stars through radio astronomy techniques. There are about 85 binary pulsars and two multiple systems known. Currently there is no formal system of designating these companions.
We present an updated phase-coherent timing solution for the young, energetic pulsar B1509–58 from twenty years of data. Using a partially phase-coherent timing analysis, we show that the second frequency derivative is changing in time, implying a third frequency derivative of This value is consistent with the simple power law model of pulsar rotation.
We present radio polarimetry results for nine Southern pulsars. Six of the nine are young, with characteristic ages less than 100 kyr and high spin-down luminosities. All six show significant linear polarization, and we confirm a previously noticed trend in which the degree of linear polarization increases with spin-down luminosity. We have used the rotating vector model to fit the observed position angle data for PSR J1513–5908 (B1509–58). We find that a magnetic inclination angle α > 60° is excluded at the 3σ level in the fit, and that the geometry suggested by the morphology of an apparent bipolar X-ray outflow is marginally inconsistent with a recent model of the pulsar magnetosphere.
Recent observations of the globular cluster 47 Tuc, made with the Parkes telescope at a wavelength of 20 cm, have resulted in the discovery of nine new millisecond pulsars (MSPs), all in binary systems. The number of timing solutions available has risen from two to 14. These results will make possible a more detailed study of the cluster dynamics.
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