A Pulsar Bonanza

Lorimer, D. R.

doi:10.1126/science.1109555

Cited by 57 publications

(96 citation statements)

References 7 publications

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“…This clearly contradicts the earlier statement of Malofeev et al (1996), which estimated the transition frequency to be around 3 GHz. This value is also higher than the transition frequency one can infer from Lorimer & Kramer (2005) -namely from their Fig. 4.3, which suggests that for a pulsar with DM = 27 pc/cm 3 ν c should be close to 4 GHz.…”

Section: General Picturementioning

confidence: 65%

“…This came from the observational experience with this pulsar and strong flux variability observed at 5 GHz, when we observed it for the purpose of estimating its spectrum (Maron et al 2000). The theory (see Lorimer & Kramer 2005, for summary) predicts that at 4.8 GHz a pulsar with DM = 26.8 pc cm −3 should be close to its transition frequency, but on the strong scintillation side as well.…”

Section: Individual Session Flux Density Variationsmentioning

confidence: 99%

“…For these objects the frequency of the switch from strong to weak scintillation regimes (i.e. the transition frequency) should be relatively low, and all theories predict the increase of refractive modulation index towards that frequency (for summary see Lorimer & Kramer 2005; also Romani et al 1986). In these cases, when the ISS timescales are of the order of tens to a few hundred minutes, typical flux density observations (which usually involve continuous integration of the length of 10 min to an hour) of a single measurement may be heavily affected by both types of scintillations.…”

Section: Scintillation Parameters At 48 Ghzmentioning

confidence: 99%

“…Depending on the strength of the scattering that the radiation of a given pulsar undergoes, the interstellar scintillations (ISS) will result in different phenomena observed for the pulsar (see Lorimer & Kramer 2005, and the references therein for a recent review). For a nearby pulsar, or when the radiation encounters only small amounts of the scattering material (and if the observing frequency is higher than ca.…”

Section: Introductionmentioning

confidence: 99%

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Diffractive and refractive timescales at 4.8 GHz in PSR B0329+54

Lewandowski

Kijak

Gupta

et al. 2011

A&A

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Aims. We present the results of flux density monitoring of PSR B0329+54 at the frequency of 4.8 GHz using the 32-m TCfA radiotelescope. The observations were conducted between 2002 and 2005. The main goal of the project was to find interstellar scintillation (ISS) parameters for the pulsar at the frequency at which it was never studied in detail. To achieve this, the 20 observing sessions consisted of 3-min integrations, which on average lasted 24 h. This gave us sufficient sensitivity to all types of flux density variations over a wide range of timescales. The character of the observations makes our project unique amongst other ISS oriented observing programs, at least at high frequency. Methods. Flux density time series obtained for each session were analysed using structure functions. For some of the individual sessions as well as for the general average structure function we were able to identify two distinctive timescales present, the timescales of diffractive and refractive scintillations. To the best of our knowledge, this is the first case when both scintillation timescales, t DISS = 42.7 min and t RISS = 305 min, were observed simultaneously in a uniform data set and estimated using the same method. Results. The obtained values of the ISS parameters combined with the data found in the literature allowed us to study the frequency dependence of these parameters over a wide range of observing frequencies, which is crucial for understanding the ISM turbulence. We found that the Kolmogorov spectrum is not best suited for describing the density fluctuations of the ISM, and a power-law spectrum with β = 4 seems to fit better with our results. We were also able to estimate the transition frequency (transition from strong to weak scintillation regimes) as ν c = 10.1 GHz, much higher than was previously predicted. We were also able to estimate the strength of scattering parameter u = 2.67 and the Fresnel scale as r F = 6.7 × 10 8 m.

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Section: General Picturementioning

confidence: 65%

Section: Individual Session Flux Density Variationsmentioning

confidence: 99%

Section: Scintillation Parameters At 48 Ghzmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Diffractive and refractive timescales at 4.8 GHz in PSR B0329+54

Lewandowski

Kijak

Gupta

et al. 2011

A&A

View full text Add to dashboard Cite

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“…The peak flux of the giant pulses were computed using the modified radiometer equation (Lorimer & Kramer 2005) for the pulsar case, S peak = (S /N) · S min . With the above considerations of the nebular contribution to T total and with T sys = 30 K in the WSRT's L-Band, the system retained sufficiently high sensitivity in the first 15 000 s of the observation.…”

Section: Flux Calibrationmentioning

confidence: 99%

Giant pulses from the Crab pulsar

Karuppusamy

Stappers

Straten³

2010

A&A

108

111

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The Crab pulsar is well-known for its anomalous giant radio pulse emission. Past studies have concentrated only on the very bright pulses or were insensitive to the faint end of the giant pulse luminosity distribution. With our new instrumentation offering a large bandwidth and high time resolution combined with the narrow radio beam of the Westerbork Synthesis Radio Telescope (WSRT), we seek to probe the weak giant pulse emission regime. The WSRT was used in a phased array mode, resolving a large fraction of the Crab nebula. The resulting pulsar signal was recorded using the PuMa II pulsar backend and then coherently dedispersed and searched for giant pulse emission. After careful flux calibration, the data were analysed to study the giant pulse properties. The analysis includes the distributions of the measured pulse widths, intensities, energies, and scattering times. The weak giant pulses are shown to form a separate part of the intensity distribution. The large number of giant pulses detected were used to analyse scattering and scintillation in giant pulses. We report for the first time the detection of giant pulse emission at both the main-and interpulse phases within a single rotation period. The rate of detection is consistent with the appearance of pulses at either pulse phase as being independent. These pulse pairs were used to examine the scintillation timescales within a single pulse period.

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Frequency stability analysis of pulsar‐aided clocks

2019

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This paper discusses the use of a pulsar signal in clock calibration. The analysis method is presented from the perspective of filtering theory, where Hadamard variance is used to analyze the frequency stability of both the stand-alone and the pulsar-aided clock systems. The aided clock is constructed using a steady state Kalman filter and accounts for the fractional power spectral density of the pulsar timing noise. The results of this simplified analysis indicate that the frequency stability of the aided clock has noticeable improvement at large averaging time due to the suppression of the random walk frequency noise in the stand-alone clock.NAVIGATION. 2019;66:621-632.wileyonlinelibrary.com/journal/navi

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A Pulsar Bonanza

Cited by 57 publications

References 7 publications

Diffractive and refractive timescales at 4.8 GHz in PSR B0329+54

Diffractive and refractive timescales at 4.8 GHz in PSR B0329+54

Giant pulses from the Crab pulsar

Frequency stability analysis of pulsar‐aided clocks

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