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Published: 4 June 2021
Last updated: 12 February 2022

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1

Wang, P. F., J. L. Han, L. Han, B. Y. Cai, C. Wang, T. Wang, X. Chen, et al. "Jiamusi pulsar observations." Astronomy & Astrophysics 644 (December 2020): A73. http://dx.doi.org/10.1051/0004-6361/202038867.

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Aims. Most pulsar nulling observations have been conducted at frequencies lower than 1400 MHz. We aim to understand the nulling behaviors of pulsars at relatively high frequencies, and to decipher whether or not nulling is caused by a global change in the pulsar magnetosphere. Methods. We used the Jiamusi 66 m telescope to observe 20 bright pulsars at 2250 MHz with unprecedented lengths of time. We estimated the nulling fractions of these pulsars, and identified the null and emission states of the pulses. We also calculated the nulling degrees and scales of the emission-null pairs to describe the distributions of emission and null lengths. Results. Three pulsars, PSRs J0248+6021, J0543+2329, and J1844+00, are found to null for the first time. The details of null-to-emission and emission-to-null transitions within the pulse window are observed for the first time for PSR J1509+5531, which is a low-probability event. A complete cycle of long nulls with timescales of hours is observed for PSR J1709−1640. For most of these pulsars, the K-S tests of nulling degrees and nulling scales reject the hypothesis that null and emission are caused by random processes at high significance levels. Emission-null sequences of some pulsars exhibit quasi-periodic, low-frequency or featureless modulations, which might be related to different origins. During transitions between emission and null states, pulse intensities have diverse tendencies for variation. Significant correlations are found between respectively nulling fraction, nulling cadence, and nulling scale and the energy loss rate of the pulsars. Combined with the nulling fractions reported in the literature for 146 nulling pulsars, we find that statistically large nulling fractions are more tightly related to pulsar period than to characteristic age or energy-loss rate.
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Wang, Na, R. N. Manchester, Aili Yusup, Xinji Wu, Jin Zhang, and Maozheng Chen. "Scintillation Observations of Strong Northern Pulsars." International Astronomical Union Colloquium 182 (2001): 57–60. http://dx.doi.org/10.1017/s0252921100000695.

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AbstractScintillation of pulsar radio emission provides information about the interstellar medium along the path to the pulsar and the velocities of pulsars. It also affects the precision of pulse timing observations. Using a pulsar timing system developed at the Urumqi Astronomical Observatory 25 m telescope, we observed diffractive scintillation dynamic spectra for several strong northern pulsars. This paper introduces the observing system and discusses the observational results.
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3

Yang, Tinggao, and Guangren Ni. "Ensemble Pulsar Time Study by Pulsar Timing Observations." Symposium - International Astronomical Union 218 (2004): 439–40. http://dx.doi.org/10.1017/s0074180900181604.

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Long term timing of multiple millisecond pulsars can contribute to the study of an ensemble pulsar time scale PTens. A wavelet decomposition algorithm (WDA) was applied to define a PTens using the available millisecond pulsar timing datA. The PTens obtained from WDA is more stable than those resulting from other algorithms. The Chinese 50 m radio telescope is specially designed for PTens study and detection of gravitational wave background via millisecond pulsars timing observations. A scheme for multiple millisecond pulsar timing and ensemble pulsar time study is discussed in some detail.
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4

Edelstein, Jerry, and Stuart Bowyer. "EUV Observations of Pulsars." International Astronomical Union Colloquium 160 (1996): 291–95. http://dx.doi.org/10.1017/s0252921100041749.

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AbstractThree pulsars have been detected with the Lexan (100 Å )filter of the EUVE Deep Survey telescope: the middle-aged isolated pulsars, PSR B0656+14 and Geminga, plus the aged millisecond pulsar PSR J0437–4715. The EUV detections have been used both alone and in combination with observations in other bandpasses to limit the physical state of the objects and to test theories regarding neutron star cooling and re-heating mechanisms. For Geminga, the EUVE data suggests the presence of an optical cyclotron spectral feature superimposed on the Rayleigh-Jeans continuum tail from a hot pulsar surface. We summarize EUV pulsar observations and results.
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5

Torne, Pablo. "Pulsar observations at millimetre wavelengths." Proceedings of the International Astronomical Union 13, S337 (September 2017): 92–95. http://dx.doi.org/10.1017/s1743921317009085.

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AbstractDetecting and studying pulsars above a few GHz in the radio band is challenging due to the typical faintness of pulsar radio emission, their steep spectra, and the lack of observatories with sufficient sensitivity operating at high frequency ranges. Despite the difficulty, the observations of pulsars at high radio frequencies are valuable because they can help us to understand the radio emission process, complete a census of the Galactic pulsar population, and possibly discover the elusive population in the Galactic Centre, where low-frequency observations have problems due to the strong scattering. During the decades of the 1990s and 2000s, the availability of sensitive instrumentation allowed for the detection of a small sample of pulsars above 10 GHz, and for the first time in the millimetre band. Recently, new attempts between 3 and 1 mm (≈86 − 300 GHz) have resulted in the detections of a pulsar and a magnetar up to the highest radio frequencies to date, reaching 291 GHz (1.03 mm). The efforts continue, and the advent of new or upgraded millimetre facilities like the IRAM 30-m, NOEMA, the LMT, and ALMA, warrants a new era of high-sensitivity millimetre pulsar astronomy in the upcoming years.
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6

Wang, Na, Jin Zhang, and Xin-Ji Wu. "Pulsar Observations in China – Status and Results." Symposium - International Astronomical Union 214 (2003): 159–62. http://dx.doi.org/10.1017/s007418090019432x.

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We present the status and results of pulsar observations in China. Pulsar observations at Urumqi Observatory over more than two years have resulted in updated rotation parameters for 74 pulsars. Comparison with earlier observations shows that long-term period and period-derivative fluctuations are probably dominated by unseen glitches. We also monitored the variation of pulsar scintillation dynamic spectra for a few strong pulsars. The data show major variations in the scintillation parameters. A new system at a lower frequency is planned to allow investigation of the frequency dependence of pulsar properties. A 50-m telescope for millisecond pulsar timing is also being planned at the National Astronomical Observatories, Beijing, and should be constructed within three years.
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7

McCulloch, P. M. "Closing Comments: Observations." International Astronomical Union Colloquium 128 (1992): 410–11. http://dx.doi.org/10.1017/s0002731600155659.

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During the course of this colloquium many papers have been presented on observational aspects of pulsar astronomy. In the following discussion I have not attempted to be comprehensive but have selected a number of areas of interest to me.The basic pulsar properties appear to be consistent over the full range of pulsar periods from 1 ms to 4s, implying that the emission mechanism is the same for all pulsars. There was a general consensus among the observers that the radio emission occurs low down in the pulsar's magnetosphere above the magnetic polar region.
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8

Collins, Susan, Andy Shearer, Ben Stappers, Cesare Barbieri, Giampiero Naletto, Luca Zampieri, Enrico Verroi, and Serena Gradari. "Crab Pulsar: Enhanced Optical Emission During Giant Radio Pulses." Proceedings of the International Astronomical Union 7, S285 (September 2011): 296–98. http://dx.doi.org/10.1017/s1743921312000841.

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AbstractAlthough optical pulsar studies have been limited to a few favoured objects, the observation of pulsars at optical wavelengths provides an opportunity to derive a number of important pulsar characteristics, including the energy spectrum of the emitting electrons and the geometry of the emission zone. These parameters will be vital for a comprehensive model of pulsar emission mechanisms. Observations of the Crab pulsar with the high-time-resolution photon-tagging photometer IquEYE show an optical–radio delay of ~178 μs. Incorporating simultaneous Jodrell Bank radio observations suggested a correlation between giant radio pulses and enhanced optical pulses for this pulsar, thus offering possible evidence for the reprocessing of radio photons.
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9

Kawai, Nobuyuki, and Keisuke Tamura. "Recent X-ray Observations of Pulsar Nebulae." International Astronomical Union Colloquium 160 (1996): 367–74. http://dx.doi.org/10.1017/s0252921100041920.

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AbstractResults from the X-ray observations of pulsars with ASCA are presented. The surroundings of pulsars are investigated in detail taking advantage of ASCA’s unique capabilities; high spectral resolution and a high throughput over a wide energy range from 0.4 keV to 10 keV. The spectral characteristics of the nebulae of PSR B1509—58 and the Vela pulsar are spectroscopically investigated. A jet-like feature is found from PSR B1509—58. We detected diffuse emission sources in the vicinity of many pulsars. The high probability of finding such diffuse sources for many pulsars suggests that they exist universally for all the active pulsars, and that they are powered by the pulsars. SNR Kes 32 was imaged in X-ray for the first time. Its X-ray properties can be used to examine its association with the nearby pulsar PSR B1610—50.
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10

Navarro, José, and R. N. Manchester. "Polarimetric Observations of PSR J0437–4715." International Astronomical Union Colloquium 160 (1996): 249–51. http://dx.doi.org/10.1017/s0252921100041622.

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To date there have been few polarimetric observations of millisecond pulsars, mainly due to the instrumental challenge of simultaneous high time resolution and large bandwidth. Such observations provide our most direct clues to the structure of the magnetic fields around pulsars, and are especially important in the case of millisecond pulsars, where radio emission necessarily originates very close to the neutron star surface.We have observed the bright millisecond pulsar J0437–4715 at the Parkes Radiotelescope with the Caltech Fast Pulsar Timing Machine, at several radio frequencies and in full polarimetric mode. Our analyses show significant deviations from the standard dipole field geometry.
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11

Wang, P. F., J. L. Han, L. Han, J. H. Zhang, J. Q. Li, C. Wang, J. Han, T. Wang, and X. Y. Gao. "Jiamusi pulsar observations." Astronomy & Astrophysics 618 (October 2018): A186. http://dx.doi.org/10.1051/0004-6361/201833215.

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Context. Pulsars scintillate. Dynamic spectra show brightness variation of pulsars in the time and frequency domain. Secondary spectra demonstrate the distribution of fluctuation power in the dynamic spectra. Aims. Dynamic spectra strongly depend on observational frequencies, but were often observed at frequencies lower than 1.5 GHz. Scintillation observations at higher frequencies help to constrain the turbulence feature of the interstellar medium over a wide frequency range and can detect the scintillations of more distant pulsars. Methods. Ten pulsars were observed at 2250 MHz (S-band) with the Jiamusi 66 m telescope to study their scintillations. Their dynamic spectra were first obtained, from which the decorrelation bandwidths and timescales of diffractive scintillation were then derived by autocorrelation. Secondary spectra were calculated by forming the Fourier power spectra of the dynamic spectra. Results. Most of the newly obtained dynamic spectra are at the highest frequency or have the longest time span of any published data for these pulsars. For PSRs B0540 + 23, B2324 + 60, and B2351 + 61, these were the first dynamic spectra ever reported. The frequency dependence of the scintillation parameters indicates that the intervening medium can rarely be ideally turbulent with a Kolmogorov spectrum. The thin-screen model worked well at S-band for the scintillation of PSR B1933 + 16. Parabolic arcs were detected in the secondary spectra of three pulsars, PSRs B0355 + 54, B0540 + 23, and B2154 + 40, all of which were asymmetrically distributed. The inverted arclets of PSR B0355 + 54 were seen to evolve along the main parabola within a continuous observing session of 12 h, from which the angular velocity of the pulsar was estimated. This was consistent with the measurement by very long baseline interferometry.
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12

Chen, Siyuan, François Vernotte, and Enrico Rubiola. "Applying clock comparison methods to pulsar timing observations." Monthly Notices of the Royal Astronomical Society 503, no. 3 (March 15, 2021): 4496–507. http://dx.doi.org/10.1093/mnras/stab742.

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ABSTRACT Frequency metrology outperforms any other branch of metrology in accuracy (parts in 10−16) and small fluctuations (<10−17). In turn, among celestial bodies, the rotation speed of millisecond pulsars is by far the most stable (<10−18). Therefore, the precise measurement of the time of arrival (TOA) of pulsar signals is expected to disclose information about cosmological phenomena, and to enlarge our astrophysical knowledge. Related to this topic, Pulsar Timing Array projects have been developed and operated for the last decades. The TOAs from a pulsar can be affected by local emission and environmental effects, in the direction of the propagation through the interstellar medium or universally by gravitational waves from super massive black hole binaries. These effects (signals) can manifest as a low-frequency fluctuation over time, phenomenologically similar to a red noise, while the remaining pulsar intrinsic and instrumental background (noise) are white. This article focuses on the frequency metrology of pulsars. From our standpoint, the pulsar is an accurate clock, to be measured simultaneously with several telescopes in order to reject the uncorrelated white noise. We apply the modern statistical methods of time-and-frequency metrology to simulated pulsar data, and we show the detection limit of the correlated red noise signal between telescopes.
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13

Gupta, Y., P. Gothoskar, and N. D. Ramesh Bhat. "First Results from Simultaneous Dual Frequency Observations of Pulsars." Symposium - International Astronomical Union 199 (2002): 369–72. http://dx.doi.org/10.1017/s0074180900169347.

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One of the unique capabilities of the GMRT is the facility for simultaneous multi-frequency observations of pulsars. We have initiated such observations with the aims of (i) studying frequency dependence of pulsar emission, (ii) accurate estimates of pulsar dispersion measure and its variations and (iii) multi-frequency interstellar scintillation studies. Here we present some results from the ongoing dual frequency observations of pulsars.
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14

Sieber, W. "Closing Comments: Observations." International Astronomical Union Colloquium 128 (1992): 408–9. http://dx.doi.org/10.1017/s0002731600155647.

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AbstractMany of the problems discussed at this conference were also on the agenda of the Bonn symposium on pulsars (IAU 95) about ten years ago, and it seems worthwhile to compare how our view of the magnetosphexe and pulsar emission has changed since then.
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15

Gallant, Y. A., R. Bandiera, N. Bucciantini, and E. Amato. "Constraining pulsar birth properties with supernova X-ray observations." Proceedings of the International Astronomical Union 12, S331 (February 2017): 63–68. http://dx.doi.org/10.1017/s1743921317004756.

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AbstractA large fraction of core-collapse supernovae are thought to result in the birth of a rotation-powered pulsar, which is later observable as a radio pulsar up to great ages. The birth properties of these pulsars, and in particular the distribution of their initial rotation periods, are however difficult to infer from studies of the radio pulsar population in our Galaxy. Yet the distributions of their birth properties is an important assumption for scenarios in which ultra-high-energy cosmic rays (UHECRs) originate in very young, extragalactic pulsars with short birth periods and/or high magnetic fields.Using a model of the very young pulsar wind nebula’s dynamical and spectral evolution, with pulsar wind and accelerated particle parameters assumed similar to those inferred from modeling young pulsar wind nebulae (PWNe) in our Galaxy, we show that X-ray observations of supernovae, a few years to decades after the explosion, constitute a favored window to obtain meaningful constraints on the initial spin-down luminosity of the newly-formed pulsar. We examine the expected emerging PWN spectral component, taking into account the X-ray opacity of the expanding supernova ejecta, and find that it is typically best detectable in < 10 keV X-rays some years after the explosion. We use this framework to assess available X-ray observations and flux upper limits on supernovae, building on the work of Pernaet al.(2008). We note that a resulting limit on spin-down luminosity corresponds univocally to a limit on the maximum magnetospheric acceleration potential, irrespective of the specific combination of magnetic field and rotation period that achieves it. We use available X-ray observations of supernovae to place constraints on the birth spin-down luminosity and period distribution of classical pulsars. We also examine the case of magnetars, born with much higher magnetic fields, and show that their much shorter initial spin-down time implies that any plausible signature of young magnetar wind nebulae can only be observed in harder X-ray or gamma-rays.
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16

Gouiffes, Christian, and Hakki Ögelman. "Optical Observations of Pulsars." International Astronomical Union Colloquium 160 (1996): 299–300. http://dx.doi.org/10.1017/s0252921100041762.

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In the course of a programme to study optical pulsars, we have observed at different occasions PSR0540-69, the 50 msec pulsar in the LMC. Like the Crab pulsar, it has been detected at X-rays, optical and radio and its braking index (∼2) determined. In this communication we report some results obtained on this pulsar, in particular the presence of narrow features in the pulse profile and compare it with a nearly simultaneous X-ray observation.The observations were carried out at the 3.6m telescope at La. Silla observatory, Chile. The instrument consisted on a single channel photometer coupled with a. photomultiplier (GaAs photocathode). The sampling frequency was 10 kHz and the output of the photon counting system was recorded sequentially on magnetic tape. A set of filters and diaphragms were available. A standard analysis was then performed. After corrections to the solar system barycenter, the data were analyzed and the best period determined using thetest (Buccheri et al, 1983).
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17

Wu, Xinji, and Wen Xu. "A Determination of Pulsar Emission Geometry from Polarization Observations." International Astronomical Union Colloquium 128 (1992): 400–403. http://dx.doi.org/10.1017/s0002731600155623.

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AbstractOne of the important problems in pulsar studies is to determine the magnetic inclination angle α, the intrinsic width of the radiation beam (2ρ) and the angle (α + β) between the observer's direction and the rotation axis. In this paper we solve this problem for individual pulses by using the observed pulse width (2Δ𝜙), the swing of polarization angle (2Δψ), and its central gradient (dψ/d𝜙)max.From the polar cap model we establish three basic geometrical relations, a complete set of equations from which explicit solutions can be obtained using the observed data. This is the first time that the orientation of pulsar emission is solved analytically solely on the basis of a geometrical model. However, the results are shown to be sensitively connected to the polarization-angle swing (2Δψ), which is not well measured for most pulsars. So the number of pulsars to which our method can be applied is limited. The importance of the measurement of Δψ is seen from our method. To ensure the credibility of our results, we have discussed the conditions to be satisfied by all reliable pulsar measurements. Our method is shown to be more favorable for pulsars with large pulse width 2Δ𝜙, large central gradient (dψ/d𝜙)max and large magnetic inclination angle α. Out of 120 pulsars (from Lyne and Manchester 1988), 40 are solvable, and 7 are believed to be reliable. We discuss our method for the determination of pulsar geometry in comparison with other methods.
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18

Dewey, Rachel J., and Anthony J. Beasley. "Phase-referenced VLBA Observations of PSRs B1937+21 and B0329+54." International Astronomical Union Colloquium 160 (1996): 115–16. http://dx.doi.org/10.1017/s0252921100041191.

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In this paper we present the preliminary results of phase-referenced VLBA observations of two pulsars PSRB1937+21 and PSRB0329+54. Since pulsar observations usually require a lower observing frequency than that used for other astrometric applications, ionospheric delays are a significant source of systematic error. For the observations presented here we used total-electron-content (TEC) measurements derived from dual-frequency GPS observations (Wilson, Mannucci &amp; Edwards, 1995) to calibrate ionospheric delays.Using this calibration technique were able to obtain positions for these two pulsars which we believe to be accurate to approximately 2 mas in each coordinate. With this level of accuracy we expect astrometric pulsar observations to be able to address a variety of interesting issues ranging from reference frame alignment and fundamental astrometry to the origin of pulsar velocities.
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19

Zhang, Xinyuan, Ping Shuai, Liangwei Huang, Shaolong Chen, and Lihong Xu. "Mission Overview and Initial Observation Results of the X-Ray Pulsar Navigation-I Satellite." International Journal of Aerospace Engineering 2017 (2017): 1–7. http://dx.doi.org/10.1155/2017/8561830.

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The newly launched X-ray pulsar navigation-I (XPNAV-1) is an experimental satellite of China that is designed for X-ray pulsar observation. This paper presents the initial observation results and aims to recover the Crab pulsar’s pulse profile to verify the X-ray instrument’s capability of observing pulsars in space. With the grazing-incidence focusing type instrument working at the soft X-ray band (0.5–10 keV), up to 162 segments of observations of the Crab pulsar are fulfilled, and more than 5 million X-ray events are recorded. Arrival times of photons are corrected to the solar system barycentre, and the 33 ms pulse period is sought out for Crab. Epoch folding of all the corrected photon times generates the refined pulse profile of Crab. The characteristic two-peak profile proves that the Crab pulsar has been clearly seen, so that the conclusion is made that XPNAV-1’s goal of being capable of observing pulsars is achieved.
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20

Hobbs, G., D. Miller, R. N. Manchester, J. Dempsey, J. M. Chapman, J. Khoo, J. Applegate, et al. "The Parkes Observatory Pulsar Data Archive." Publications of the Astronomical Society of Australia 28, no. 3 (2011): 202–14. http://dx.doi.org/10.1071/as11016.

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AbstractThe Parkes pulsar data archive currently provides access to 144044 data files obtained from observations carried out at the Parkes observatory since the year 1991. Around 105 files are from surveys of the sky, the remainder are observations of 775 individual pulsars and their corresponding calibration signals. Survey observations are included from the Parkes 70 cm and the Swinburne Intermediate Latitude surveys. Individual pulsar observations are included from young pulsar timing projects, the Parkes Pulsar Timing Array and from the PULSE@Parkes outreach program. The data files and access methods are compatible with Virtual Observatory protocols. This paper describes the data currently stored in the archive and presents ways in which these data can be searched and downloaded.
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21

Gancio, G., C. O. Lousto, L. Combi, S. del Palacio, F. G. López Armengol, J. A. Combi, F. García, et al. "Upgraded antennas for pulsar observations in the Argentine Institute of Radio astronomy." Astronomy & Astrophysics 633 (January 2020): A84. http://dx.doi.org/10.1051/0004-6361/201936525.

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Context. The Argentine Institute of Radio astronomy (IAR) is equipped with two single-dish 30 m radio antennas capable of performing daily observations of pulsars and radio transients in the southern hemisphere at 1.4 GHz. Aims. We aim to introduce to the international community the upgrades performed and to show that the IAR observatory has become suitable for investigations in numerous areas of pulsar radio astronomy, such as pulsar timing arrays, targeted searches of continuous gravitational waves sources, monitoring of magnetars and glitching pulsars, and studies of a short time scale interstellar scintillation. Methods. We refurbished the two antennas at IAR to achieve high-quality timing observations. We gathered more than 1000 h of observations with both antennas in order to study the timing precision and sensitivity they can achieve. Results. We introduce the new developments for both radio telescopes at IAR. We present daily observations of the millisecond pulsar J0437−4715 with timing precision better than 1 μs. We also present a follow-up of the reactivation of the magnetar XTE J1810–197 and the measurement and monitoring of the latest (Feb. 1, 2019) glitch of the Vela pulsar (J0835–4510). Conclusions. We show that IAR is capable of performing pulsar monitoring in the 1.4 GHz radio band for long periods of time with a daily cadence. This opens up the possibility of pursuing several goals in pulsar science, including coordinated multi-wavelength observations with other observatories. In particular, daily observations of the millisecond pulsar J0437−4715 would increase the sensitivity of pulsar timing arrays. We also show IAR’s great potential for studying targets of opportunity and transient phenomena, such as magnetars, glitches, and fast-radio-burst sources.
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22

Nowakowski, Leszek A. "Finding Pulsar Emission Heights from Dual–Frequency Observations." International Astronomical Union Colloquium 177 (2000): 219–20. http://dx.doi.org/10.1017/s0252921100059510.

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AbstractWe present a method that allows to find the radial separation of regions emitting individual components of pulsar average profiles at two radio frequencies. It may also be used for single–frequency observations in pulsars that have intensity–dependent average profiles and/or mode–switching. Preliminary results for three radio pulsars are presented, obtained using average profiles from non-simultaneous observations.
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23

Kuzmin, Arkady, and Boris Losovsky. "Observations of millisecond pulsars at 102 MHz." International Astronomical Union Colloquium 177 (2000): 235–36. http://dx.doi.org/10.1017/s0252921100059558.

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24

Guillemot, L. "Radio counterparts of gamma-ray pulsars." Proceedings of the International Astronomical Union 8, S291 (August 2012): 87–92. http://dx.doi.org/10.1017/s1743921312023241.

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AbstractObservations of pulsars with the Large Area Telescope (LAT) on the Fermi satellite have revolutionized our view of the gamma-ray pulsar population. For the first time, a large number of young gamma-ray pulsars have been discovered in blind searches of the LAT data. More generally, the LAT has discovered many new gamma-ray sources whose properties suggest that they are powered by unknown pulsars. Radio observations of gamma-ray sources have been key to the success of pulsar studies with the LAT. For example, radio observations of LAT-discovered pulsars provide constraints on the relative beaming fractions, which are crucial for pulsar population studies. Also, radio searches of LAT sources with no known counterparts have been very efficient, with the discovery of over forty millisecond pulsars. I review radio follow-up studies of LAT-discovered pulsars and unidentified sources, and discuss some of the implications of the results.
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25

Parent, E., V. M. Kaspi, S. M. Ransom, C. Patel, and M. Krasteva. "The implementation of a Fast-Folding Algorithm in the PALFA survey." Proceedings of the International Astronomical Union 13, S337 (September 2017): 388–89. http://dx.doi.org/10.1017/s1743921317008638.

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AbstractThe PALFA survey, the most sensitive blind search for radio pulsars, has now discovered 180 pulsars in the Galactic Plane, the vast of which have periods shorter than 2 seconds. One reason that pulsar surveys may miss long-period radio pulsars is the strong effect of red noise at low modulation frequencies. It is possible to address this reduction in sensitivity by using a Fast-Folding Algorithm (FFA). We have adapted this algorithm for radio pulsar searching and applied it to PALFA observations. A sensitivity analysis of the algorithm has been conducted using synthetic pulsar signals injected in real observational data and this study shows that the FFA improves the PALFA survey sensitivity, as reported in Lazarus et al.(2015), by at least a factor of two at periods of ~6 sec, implying that the PALFA survey should discover more long-period radio pulsars in the future.
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26

Kuz'min, A. D., Yu I. Alekseev, K. A. Lapaev, B. Ya Losovsky, and A. A. Salnikov. "Observations of the Millisecond Pulsar PSR 1855+09 At 102 MHz." International Astronomical Union Colloquium 128 (1992): 213. http://dx.doi.org/10.1017/s0002731600155155.

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AbstractThe study of millisecond pulsars is of great astrophysical interest. One may expect that the rotation effect on the structure of the magnetosphere should be very significant. In view of the short duration of the pulses they are very suitable for investigations of the interstellar medium; at least they hold the promise for the pulsar time scale.Millisecond pulsars were discovered and have been studied on the basis of their radio-emission at decimeter wavelengths. At longer wavelengths scattering of the radio emission in the interstellar medium is the principal limitation of millisecond pulsar observations.
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27

Guillemot, L., F. Octau, I. Cognard, G. Desvignes, P. C. C. Freire, D. A. Smith, G. Theureau, and T. H. Burnett. "Timing of PSR J2055+3829, an eclipsing black widow pulsar discovered with the Nançay Radio Telescope." Astronomy & Astrophysics 629 (September 2019): A92. http://dx.doi.org/10.1051/0004-6361/201936015.

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We report on the timing observations of the millisecond pulsar PSR J2055+3829 originally discovered as part of the SPAN512 survey conducted with the Nançay Radio Telescope. The pulsar has a rotational period of 2.089 ms and is in a tight 3.1 h orbit around a very low mass (0.023 ≤ mc ≲ 0.053 M⊙, 90% c.l.) companion. Our 1.4 GHz observations reveal the presence of eclipses of the radio signal of the pulsar, caused by the outflow of material from the companion, for a few minutes around superior conjunction of the pulsar. The very low companion mass, the observation of radio eclipses, and the detection of time variations of the orbital period establish PSR J2055+3829 as a “black widow” (BW) pulsar. Inspection of the radio signal from the pulsar during ingress and egress phases shows that the eclipses in PSR J2055+3829 are asymmetric and variable, as is commonly observed in other similar systems. More generally, the orbital properties of the new pulsar are found to be very similar to those of other known eclipsing BW pulsars. No gamma-ray source has been detected at the location of the pulsar in recent Fermi-LAT source catalogs. We used the timing ephemeris to search ten years of Fermi Large Area Telescope (LAT) data for gamma-ray pulsations, but were unable to detect any. This non-detection could be a consequence of the large distance of the pulsar compared to those of known gamma-ray millisecond pulsars outside of globular clusters. We finally compared the mass functions of eclipsing and non-eclipsing BW pulsars and confirmed previous findings that eclipsing BWs have higher mass functions than their non-eclipsing counterparts. Larger inclinations could explain the higher mass functions of eclipsing BWs. On the other hand, the mass function distributions of Galactic disk and globular cluster BWs appear to be consistent, suggesting, despite the very different environments, the existence of common mechanisms taking place in the last stages of evolution of BWs.
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28

Pilia, Maura, Alessio Trois, Matteo Bachetti, Alberto Pellizzoni, Elise Egron, Maria Noemi Iacolina, and Sara Loru. "A multi-wavelength pipeline for pulsar observations." Proceedings of the International Astronomical Union 13, S337 (September 2017): 394–95. http://dx.doi.org/10.1017/s1743921317008687.

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AbstractThe Astronomical Observatory in Cagliari (OAC) is a growing facility with a group devoted to pulsar studies across the electromagnetic spectrum. Taking advantage of this expertise we have worked to provide a suite of multi-wavelength software and databases for the observations of pulsars and compact Galactic objects at the Sardinia Radio Telescope (SRT, Bolli et al. 2015, Prandoni et al. 2017).
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29

Izvekova, V. A., A. D. Kuz'min, V. M. Malofeev, W. Sieber, A. Jessner, and R. Wielebinski. "New Observations of the Time Alignment of Pulse Profiles at High and Low Frequencies." International Astronomical Union Colloquium 128 (1992): 7–8. http://dx.doi.org/10.1017/s0002731600154630.

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Exact timing measurements allow a determination of the phase shift between observations of a pulsar at different frequencies. It has become clear from these observations that a simple dipole magnetic field configuration can not explain the time lag observed for many pulsars between profiles at high frequencies (Kuz'min et al. 1986).There are cases which might better be explained by a combination of dipole and quadrupole field components (Davies et al. 1984). We report in this paper on new pulsar time alignment observations of a number of pulsars at high and low frequencies which support the general picture outlined above.
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30

Hobbs, G. "Developing a pulsar-based time standard." Proceedings of the International Astronomical Union 10, H16 (August 2012): 207–8. http://dx.doi.org/10.1017/s1743921314005432.

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AbstractWe describe how observations of pulsars from the Parkes Pulsar Timing Array (PPTA) project have been used to develop a pulsar-based timescale. This is the first such timescale that has a precision comparable to uncertainties in international atomic timescales.
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31

Rammala, Isabella, Aris Karastergiou, and Griffin Foster. "Broadband observations of pulsar profiles and frequency dependent DMs." Proceedings of the International Astronomical Union 13, S337 (September 2017): 400–401. http://dx.doi.org/10.1017/s1743921317010353.

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AbstractThe aim of our project is to search for ways to best extract information on pulsar profiles and the interstellar medium (ISM), using the wide frequency bands that are typical of radio telescopes today. Pulsar profiles typically show a strong dependence on frequency. This depends both on the intrinsic radio emission mechanism, and the interaction of the radio waves with the ISM that lies between the pulsars and our detectors on Earth, due mostly to the effects of dispersion and scattering. In this work, we make use of radio pulsar beam models from the existing literature, to generate simulated pulse profiles, observed across various bands (centre frequencies and bandwidths), for each beam model. For all the chosen geometric parameters of the pulsar beam, observed in any frequency band, the simulated profiles manifest a relative shift in phase in their observed components, as a result of the intrinsic profile evolution. This relative shift in phase could be interpreted as an additional component to the ISM induced dispersion measure (DM). This additional DM component due to profile evolution is frequency dependent. We discuss the systematics introduced to pulsar data due to this effect.
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32

WANG, N., J. P. YUAN, Z. Y. LIU, J. B. WANG, and C. ZHU. "RECENT PROGRESS ON PULSAR OBSERVATIONS AT NANSHAN." International Journal of Modern Physics: Conference Series 23 (January 2013): 152–56. http://dx.doi.org/10.1142/s2010194513011215.

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Recent results of pulsar observations at Nanshan are present in this paper. In total 47 glitches were detected in the young pulsars, including a giant glitch in PSR B2334+61. We also investigated the scintillation parameters with the quasi-continuous observations of PSR B0329+54 spanning twenty days. Mainly using the same dataset, consecutive mode-switching events were analyzed in pulse profiles of PSR B0329+54.
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33

Liu, Kuo. "Update on the European Pulsar Timing Array." Proceedings of the International Astronomical Union 8, S291 (August 2012): 180. http://dx.doi.org/10.1017/s1743921312023575.

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AbstractThe European Pulsar Timing Array (EPTA) is one the of three global Pulsar Timing Array communities, aiming to use the clock nature of pulsars to detect gravitational wave. In this talk, I will provide an introduction to the current status of EPTA pulsar observations and present an overview of the recent results. I will also give an update on the progress of the Large European Array for Pulsar (LEAP) project, which attempts to coherently combine the data from the five biggest single site radio telescopes in Europe and make an equivalently 200-metre diameter dish. The LEAP project is an ideal effort in performing high precision pulsar timing and studying characteristics of single pulses from millisecond pulsars.
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34

Siemion, Andrew, Matthew Bailes, Geoff Bower, Jayanth Chennamangalam, Jim Cordes, Paul Demorest, Julia Deneva, et al. "A search for pulsars in the central parsecs of the Galactic center." Proceedings of the International Astronomical Union 8, S291 (August 2012): 57. http://dx.doi.org/10.1017/s1743921312023149.

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AbstractThe discovery of a pulsar or pulsars orbiting near the Galactic Center (GC) could offer an unprecedented probe of strong-field gravity, the properties of our galaxy's supermassive black hole and insights into the paradoxical star formation history of the region. However, searching for pulsars near the GC is severely hampered by the large electron densities along our line of sight and the scattering-induced pulse broadening of the pulsar emission observed through it. As the broadened pulse length approaches the pulsar period, the periodicity in pulsar emission becomes nearly undetectable. Searches extended to higher frequencies, in an effort to reduce scattering, suffer from reduced intrinsic flux, higher system temperatures and increased atmospheric opacity. We are currently attempting to mitigate the challenges associated with searching for pulsars near the GC by employing new wide bandwidth receivers, upgraded IF distribution systems and novel digital spectrometers in a GC pulsar search campaign at the Green Bank Telescope in West Virginia, USA.Our search will cover two frequency bands, from 12-15 GHz (Ku Band) and 18-26 GHz (K Band), during a total of approximately 30 hours of observations, with expected characteristic 10-sigma sensitivities between 5-10 micro-Jy. Our first observations are scheduled for mid-March 2012. Here we will present the status of our observations and initial results.
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35

Sobey, C. "Studying Magnetic Fields using Low-frequency Pulsar Observations." Proceedings of the International Astronomical Union 13, S337 (September 2017): 299–303. http://dx.doi.org/10.1017/s1743921317009267.

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AbstractLow-frequency polarisation observations of pulsars, facilitated by next-generation radio telescopes, provide powerful probes of astrophysical plasmas that span many orders of magnitude in magnetic field strength and scale: from pulsar magnetospheres to intervening magneto-ionic plasmas including the ISM and the ionosphere. Pulsar magnetospheres with teragauss field strengths can be explored through their numerous emission phenomena across multiple frequencies, the mechanism behind which remains elusive. Precise dispersion and Faraday rotation measurements towards a large number of pulsars probe the three-dimensional large-scale (and eventually small-scale) structure of the Galactic magnetic field, which plays a role in many astrophysical processes, but is not yet well understood, especially towards the Galactic halo. We describe some results and ongoing work from the Low Frequency Array (LOFAR) and the Murchison Widefield Array (MWA) radio telescopes in these areas. These and other pathfinder and precursor telescopes have reinvigorated low-frequency science and build towards the Square Kilometre Array (SKA), which will make significant advancements in studies of astrophysical magnetic fields in the next 50 years.
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36

Kuzmin, Arkady. "Low frequency Observations of Millisecond Pulsars." Symposium - International Astronomical Union 199 (2002): 389–92. http://dx.doi.org/10.1017/s0074180900169426.

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We present results of the first low frequency measurements of integrated profiles and flux densities of a large set of millisecond pulsars at 102 MHz. Combining our observations with data at higher frequencies, borrowed from literature we performed the comparative analysis of the frequency dependence of profile width and spectra of millisecond and normal pulsars, searching for similarities and differences between their properties. Millisecond pulsars are differ to “normal” ones in much weaker frequency dependence of the width of integrated profile and the absence of the low- frequency turn-over in pulsar spectra.
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37

Perrodin, D., M. Burgay, A. Corongiu, M. Pilia, A. Possenti, M. N. Iacolina, E. Egron, et al. "Pulsar science at the Sardinia Radio Telescope." Proceedings of the International Astronomical Union 13, S337 (September 2017): 392–93. http://dx.doi.org/10.1017/s1743921317009097.

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AbstractThe Sardinia Radio Telescope (SRT) is a modern, fully-steerable 64-m dish located in San Basilio, Sardinia (Italy). It is characterized by an active surface that allows it to cover a wide range of radio frequencies (300 MHz to 100 GHz). During SRT’s commissioning phase, we installed the hardware and software needed for pulsar observations. Since then, SRT has taken part in Large European Array for Pulsars and European Pulsar Timing Array observations for the purpose of gravitational wave detection. We have installed a new S-band receiver that will allow us to search for pulsars in the Galactic Center. We also plan to combine our efforts to search for Extraterrestrial Intelligence (SETI) with the search for pulsars and Fast Radio Bursts.
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38

Eatough, R. P., P. Torne, G. Desvignes, M. Kramer, R. Karuppusamy, B. Klein, L. G. Spitler, et al. "Multi-epoch searches for relativistic binary pulsars and fast transients in the Galactic Centre." Monthly Notices of the Royal Astronomical Society 507, no. 4 (August 17, 2021): 5053–68. http://dx.doi.org/10.1093/mnras/stab2344.

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ABSTRACT The high stellar density in the central parsecs around the Galactic Centre makes it a seemingly favourable environment for finding relativistic binary pulsars. These include pulsars orbiting other neutron stars, stellar-mass black holes, or the central supermassive black hole, Sagittarius A*. Here, we present multi-epoch pulsar searches of the Galactic Centre at four observing frequencies, $4.85,\, 8.35,\, 14.6,\, 18.95\, {\rm GHz}$, using the Effelsberg 100-m radio telescope. Observations were conducted 1 yr prior to the discovery of, and during monitoring observations of, the Galactic Centre magnetar PSR J1745−2900. Our data analysis features acceleration searches on progressively shorter time series to maintain sensitivity to relativistic binary pulsars. The multi-epoch observations increase the likelihood of discovering transient or nulling pulsars, or ensure orbital phases are observed at which acceleration search methods work optimally. In ${\sim}147\, {\rm h}$ of separate observations, no previously undiscovered pulsars have been detected. Through calibration observations, we conclude this might be due to insufficient instantaneous sensitivity, caused by the intense continuum emission from the Galactic Centre, its large distance, and, at higher frequencies, the aggregate effect of steep pulsar spectral indices and atmospheric contributions to the system temperature. Additionally, we find that for millisecond pulsars in wide circular orbits $({\lesssim}800\, {\rm d})$ around Sagittarius A*, linear acceleration effects cannot be fully corrected in deep observations $(9\, {\rm h})$ with existing software tools. Pulsar searches of the Galactic Centre with the next generation of radio telescopes – such as MeerKat, ngVLA, and SKA1-mid – will have improved chances of uncovering this elusive population.
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39

Bao, Yiwei, Yang Chen, and Siming Liu. "Is PSR J0855−4644 responsible for the 1.4 TeV electron spectral bump hinted by DAMPE?" Monthly Notices of the Royal Astronomical Society 500, no. 4 (October 27, 2020): 4573–77. http://dx.doi.org/10.1093/mnras/staa3311.

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ABSTRACT DAMPE observation on the cosmic ray electron spectrum hints a narrow excess at ∼1.4 TeV. Although the excess can be ascribed to dark matter particles, pulsars and pulsar wind nebulae are believed to be more natural astrophysical origins: electrons injected from nearby pulsars at their early ages can form a bump-like feature in the spectrum due to radiative energy losses. In this paper, with a survey of nearby pulsars, we filter out four pulsars that may have notable contributions to ∼1.4 TeV cosmic ray electrons. Among them, PSR J0855−4644 has a spin-down luminosity more than 50 times higher than others and presumably dominates the electron fluxes from them. X-ray observations on the inner compact part (which may represent a tunnel for the transport of electrons from the pulsar) of PWN G267.0−01.0 are then used to constrain the spectral index of high-energy electrons injected by the pulsar. We show that high-energy electrons released by PSR J0855−4644 could indeed reproduce the 1.4 TeV spectral feature hinted by the DAMPE with reasonable parameters.
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40

Hartman, J. W. "The velocity distribution of young radio pulsars: simulating the observations." International Astronomical Union Colloquium 160 (1996): 53–54. http://dx.doi.org/10.1017/s0252921100041014.

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Lyne &amp; Lorimer (1994) argue that the velocities of young pulsars are much higher than was previously thought. However, recent radio pulsar population synthesis work by Hartman et al. (1996, these proceedings) shows that simulations that use a birth velocity distribution with more pulsars at low velocities, Phinney’s modification of the Paczyński (1990) distributiondescribes the observed magnetic field, period and luminosity distribution equally well as simulations that use the Lyne &amp; Lorimer distribution.We use this radio pulsar population synthesis model to obtain the proper motion distribution of the simulated sample, and from that we calculate the transverse velocity distribution to compare it with the observed transverse velocity distribution. A full report of this work will be given in Hartman (1996).
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41

Doroshenko, O. V., Yu P. Ilyasov, and V. V. Oreshko. "Pulsar timing at Kalyazin (Russia)." International Astronomical Union Colloquium 177 (2000): 57–60. http://dx.doi.org/10.1017/s0252921100059017.

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AbstractRegular timing observations of millisecond and binary pulsars are made with the 64-m radio telescope at Kalyazin (Russia). Filterbank 160-channel receiver is used for observations at 0.6 GHz in two circular orthogonal polarization. Precise local time service (based upon a rubidium standards and hydrogen maser) is used for measurements of Times-of-Arrival (TOA) from radio pulsars. A local time scale is compared by GPS and TV-systems with the basic AT-scales (UTC(USNO) and UTC(SU)) within an accuracy about 50nsper day. Recently the second 1.4 GHz receiver (250 kHz × 64 channels) was constructed and installed at Kalyazin radio telescope. There is a possibility to combine a part of the 1.4 GHz back-end with the 2.2 GHz front-end to produce timing observations at three frequencies simultaneously. We present a results of precise timing observations conducted by the Kalyazin pulsar system. Most of data were obtained at 0.6 GHz in 1997–1999. The data will be used for valuable applications in fundamental metrology, interstellar medium, general relativity and pulsar physics itself.
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42

Usov, Vladimir V. "Radiating Regions in Pulsar Magnetospheres: From Theory to Observations and Back." International Astronomical Union Colloquium 177 (2000): 417–20. http://dx.doi.org/10.1017/s0252921100060176.

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AbstractWe discuss plausible locations of radiating regions in the magnetospheres of pulsars and argue that the mechanisms of pulsar radiation at different frequencies are closely connected with the locations of the radiating regions, especially in the radio range. If the region that is responsible for the bulk of the non-thermal radiation at some frequency is localized in the pulsar magnetosphere then the nature of this radiation will be either determined or, at least, restricted significantly.
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43

Kaspi, V. M. "High-Precision Timing of Millisecond Pulsars and Precision Astrometry." Symposium - International Astronomical Union 166 (1995): 163–71. http://dx.doi.org/10.1017/s0074180900228027.

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We present the technique of long-term, high-precision timing of millisecond pulsars as applied to precision astrometry. We provide a tutorial on pulsars and pulsar timing, as well as up-to-date results of long-term timing observations of two millisecond pulsars, PSRs B1855+09 and B1937+21. We consider the feasibility of tying the extragalactic and optical reference frames to that defined by solar system objects, and we conclude that precision astrometry from millisecond pulsar timing has a bright future.
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44

Wietfeldt, R. D., and D. A. Frail. "Burst Mode VLBI and Pulsar Applications." International Astronomical Union Colloquium 131 (1991): 76–80. http://dx.doi.org/10.1017/s0252921100013087.

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AbstractThe technique of Burst Mode (BM) VLBI is described and its particular application to the observations of pulsars is explored. The wideband pulsed radiation from these objects is exploited to acquire data at two ends of an interferometer baseline in high-speed bursts and only during the pulsar on-times. The result at the VLBI correlator is an improvement in sensitivity by as much as the inverse pulsar duty cycle, and is a consequence of the bandwidth expansion offered by BM and the intrinsic use of gating. As a result, precision astrometrical studies of pulsars will benefit through the greatly increased instantaneous bandwidths achieved by pulsar BM. The problems, implications, and limitations of acquiring and processing pulsar BM data are discussed.
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45

Hobbs, G. "Pulsar timing array projects." Proceedings of the International Astronomical Union 5, S261 (April 2009): 228–33. http://dx.doi.org/10.1017/s1743921309990445.

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AbstractPulsars are amongst the most stable rotators known in the Universe. Over many years some millisecond pulsars rival the stability of atomic clocks. Comparing observations of many such stable pulsars may allow the first direct detection of gravitational waves, improve the Solar System planetary ephemeris and provide a means to study irregularities in terrestrial time scales. Here we review the goals and status of current and future pulsar timing array projects.
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46

Larchenkova, T. I., and O. V. Doroshenko. "A Possible Manifestation Of Microlensing In Pulsar Timing." Symposium - International Astronomical Union 173 (1996): 239–40. http://dx.doi.org/10.1017/s0074180900231409.

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Gravitational lensing and the time delay of a pulsar signal in the gravitational field of a mass are General Relativistic effects that may be used as a tool to detect the observational parameters of dark matter in our Galaxy. We propose to use observations of the time delay of pulses from pulsars to detect lensing objects located close to the line of the sight, to study the distribution of dark matter in our Galaxy. We discuss the possibility of finding such an event by measuring the delay of pulses from a pulsar, and apply it to data for PSR B0525+21.
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47

Bower, Geoffrey C. "The Galactic center pulsar SGR J1745–29." Proceedings of the International Astronomical Union 9, S303 (October 2013): 444–48. http://dx.doi.org/10.1017/s1743921314001100.

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AbstractThe discovery of the Galactic center pulsar SGR J1745–29 has provided an important new window into plasma processes in the Galactic center (GC) interstellar medium, the population of compact objects in the GC, and the prospects for probing general relativistic effects through timing of a Sgr A* pulsar companion. We discuss here radio observations of the pulsar and how they are providing fresh insights. In particular, our results show that recent pulsar surveys had the sensitivity to detect many pulsars in the GC region without significant losses due to interstellar scattering. This raise the question of why only this pulsar close to Sgr A* has been detected.
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48

Hobbs, G., L. Guo, R. N. Caballero, W. Coles, K. J. Lee, R. N. Manchester, D. J. Reardon, et al. "A pulsar-based time-scale from the International Pulsar Timing Array." Monthly Notices of the Royal Astronomical Society 491, no. 4 (November 4, 2019): 5951–65. http://dx.doi.org/10.1093/mnras/stz3071.

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ABSTRACT We have constructed a new time-scale, TT(IPTA16), based on observations of radio pulsars presented in the first data release from the International Pulsar Timing Array (IPTA). We used two analysis techniques with independent estimates of the noise models for the pulsar observations and different algorithms for obtaining the pulsar time-scale. The two analyses agree within the estimated uncertainties and both agree with TT(BIPM17), a post-corrected time-scale produced by the Bureau International des Poids et Mesures (BIPM). We show that both methods could detect significant errors in TT(BIPM17) if they were present. We estimate the stability of the atomic clocks from which TT(BIPM17) is derived using observations of four rubidium fountain clocks at the US Naval Observatory. Comparing the power spectrum of TT(IPTA16) with that of these fountain clocks suggests that pulsar-based time-scales are unlikely to contribute to the stability of the best time-scales over the next decade, but they will remain a valuable independent check on atomic time-scales. We also find that the stability of the pulsar-based time-scale is likely to be limited by our knowledge of solar-system dynamics, and that errors in TT(BIPM17) will not be a limiting factor for the primary goal of the IPTA, which is to search for the signatures of nano-Hertz gravitational waves.
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49

Brook, Paul, and Aris Karastergiou. "Finding Pulsar Variability in 50 Years of Data." Proceedings of the International Astronomical Union 13, S337 (September 2017): 317–18. http://dx.doi.org/10.1017/s1743921317008766.

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AbstractFifty years of pulsar data has led to the discovery of emission and rotation variability on timescales of months and years; we have developed techniques to identify this long timescale variability. Individual observations may be too noisy to identify subtle changes in a pulse profile; we use Gaussian process regression to model noisy observations and produce a continuous map of pulse profile variability. Generally, multiple observing epochs are required to obtain the pulsar spin frequency derivative. Gaussian process regression is, therefore, also used to monitor this rate of spindown. We have applied variability detection techniques to both millisecond and long period pulsar datasets. I will discuss the techniques used and present the most interesting results from the pulsars analysed.
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50

Hobbs, George, and Shi Dai. "Gravitational wave research using pulsar timing arrays." National Science Review 4, no. 5 (September 1, 2017): 707–17. http://dx.doi.org/10.1093/nsr/nwx126.

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Abstract A pulsar timing array (PTA) refers to a program of regular, high-precision timing observations of a widely distributed array of millisecond pulsars. Here we review the status of the three primary PTA projects and the joint International Pulsar Timing Array project. We discuss current results related to ultra-low-frequency gravitational wave searches and highlight opportunities for the near future.
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