PL612 LOFAR station sensitivity measurements in the context of its application for pulsar observations

Błaszkiewicz, Leszek; Lewandowski, Wojciech; Krankowski, Andrzej; Kijak, J.; Froń, Adam; Sidorowicz, Tomasz; Dąbrowski, Bartosz; Kotulak, Kacper; Hajduk, M.

doi:10.1016/j.asr.2018.06.047

Cited by 6 publications

(5 citation statements)

References 39 publications

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“…Out of these three sources, in this study, only observations from CasA and CygA were presented because TauA was at very low elevation angles during the time intervals considered. In general, as the noise level varies from a few Jy up to tens of Jy as a function of the zenith angle (Błaszkiewicz et al, 2018), the signal-to-noise ratio for CasA and CygA is approximately of the order of 2710 and 2214, respectively: assuming a noise level of few tens of Jy, these values amount approximately to 34 dB and 33 dB, respectively.…”

Section: General Considerations About Signal Levelsmentioning

confidence: 99%

Towards the possibility to combine LOFAR and GNSS measurements to sense ionospheric irregularities

Flisek,

Forte,

Fallows

et al. 2023

J. Space Weather Space Clim.

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Inhomogeneities within the ionospheric plasma density affect trans-ionospheric radio signals, causing radio wave scintillation in the amplitude and phase of the signals. The amount of scintillation induced by ionospheric irregularities typically decreases with the radio wave frequency. As the ionosphere affects a variety of technological systems (e.g., civil aviation, financial operations) as well as low-frequency radio astronomy observations, it is important to detect and monitor ionospheric effects with higher accuracy than currently available. Here, a novel methodology for the detection and characterization of ionospheric irregularities is established on the basis of LOFAR (Low-Frequency Array) scintillation measurements at Very High Frequency (VHF) that take into account the lack of ergodicity in the intensity fluctuations induced by scintillation. The methodology estimates the S4 scintillation index originating from irregularities with spatial scales in the inertial sub-range of electron density fluctuations in the ionosphere. The methodology is illustrated by means of observations that were collected through the Polish LOFAR stations located in Bałdy, Borowiec and Łazy: its validation was carried out by comparing LOFAR VHF scintillation observations with independent Global Navigation Satellite Systems (GNSS) observations that were collected through a high-rate receiver located near the LOFAR station in Bałdy as well as through geodetic receivers from the Polish ASG-EUPOS network. Two case studies are presented: 31 March 2017 and 28 September 2017. The comparison between LOFAR S4 observations and independent ionospheric measurements of both scintillation and rate of change of Total Electron Content (TEC) from GNSS reveals that the sensitivity of LOFAR and GNSS to ionospheric structures is different as a consequence of the frequency dependency of radio wave scintillation. Furthermore, it can be noticed that observations of LOFAR VHF scintillation can be utilised to detect plasma structures forming in the mid-latitude ionosphere, including electron density gradients occurring over spatial scales that are not necessarily detected through traditional GNSS measurements: the detection of all spatial scales is important for correct monitoring and modelling of ionospheric processes. Hence, the different sensitivity of LOFAR to ionospheric structures, in addition to traditional GNSS ionospheric measurements, allows us to expand the knowledge of ionospheric processes.

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Section: General Considerations About Signal Levelsmentioning

confidence: 99%

Towards the possibility to combine LOFAR and GNSS measurements to sense ionospheric irregularities

Flisek,

Forte,

Fallows

et al. 2023

J. Space Weather Space Clim.

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“…The Low Band Antennas (LBAs) and the High Band Antennas (HBAs). Both antenna fields forming the LOFAR station are described in detail by [ 31 ].…”

Section: Observationsmentioning

confidence: 99%

“…The PL612 LOFAR station in Bałdy in the pulsar observations mode see [ 32 ] uses a sampled signal from antennas (a clock time/frequency of 5 ns/200 MHz) as the receiver unit input and set band in the selected frequency range. A specially prepared pipeline for pulsar observations described in detail by [ 31 ] was also used. In this work the signal from HBA antennas passes through a Polyphase Filter Bank with 512 subbands, each 195.3125 kHz wide.…”

Section: Observationsmentioning

confidence: 99%

“…For the targets of our experiment we have chosen two bright pulsars previously observed with LOFAR (see e.g., [ 35 ]). In our previous work we used the data to measurements of sensitivity of the PL612 LOFAR station [ 31 ]. Both pulsars were also targets in long term flux density variations study by Esamdin et al [ 36 ].…”

Section: Observationsmentioning

confidence: 99%

“…PSR J0332+5434 (also known as B0329+54) discovered in 1968 [ 37 ] is one of the brightest pulsars in the northern hemisphere with the flux of about 1500 mJy (The jansky (symbol: Jy) is a non-SI unit of spectral flux density. 1 Jy = 10 −26 W·m −2 ·Hz −1 ) at 400 MHz [ 31 , 38 ]. J0332+5434, rotates with a period of 0.71452 s. The distance to the pulsar, the estimation of which is based on the Galactic electron density distribution, was calculated by [ 36 ] to be at 1,43 kpc (The parsec (symbol: pc) is an astronomical unit of length used to measure distances.…”

Section: Observationsmentioning

confidence: 99%

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Finding the Ionospheric Fluctuations Reflection in the Pulsar Signals’ Characteristics Observed with LOFAR

Błaszkiewicz

Flisek

Kotulak

et al. 2020

Sensors

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Pulsars’ signals reaching the atmosphere can be considered being stable under certain assumptions. In such a case the ionosphere remains the main factor distorting signal from the extraterrestrial sources, particularly if we observe them at long radio waves. In this article we present the results of the analysis of relative peak flux changes for two selected pulsars: PSR J0332+5434 (B0329+54) and PSR J1509+5531 (B1508+55), observed with the long radio wave sensor (The PL612 Low Frequency Array (LOFAR) station in Bałdy), together with the analysis of Rate of TEC (ROT) parameter changes measured with the Global Navigation Satellite Systems (GNSS) sensor (IGS LAMA station (IGS: International GSSN Service)). The main objective of the work is to find if the rapid plasma density (observed with the Rate of Total Electron Content (TEC)) has a counterpart in the pulsar observation characteristics. This focuses the attention on ionosphere influence during pulsar investigations at low radio frequencies. Additionally, what was the aim of this work, our results give reasons for using pulsar signals from LOFAR together with GNSS data as multi instrumental ionosphere state probes. Our results show a clear anti-correlation between the ROT and the pulsar profile’s peak flux trends.

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Comparative measurements of radio frequency interference in the 10–250 MHz

et al. 2021

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PL612 LOFAR station sensitivity measurements in the context of its application for pulsar observations

Cited by 6 publications

References 39 publications

Towards the possibility to combine LOFAR and GNSS measurements to sense ionospheric irregularities

Towards the possibility to combine LOFAR and GNSS measurements to sense ionospheric irregularities

Finding the Ionospheric Fluctuations Reflection in the Pulsar Signals’ Characteristics Observed with LOFAR

Comparative measurements of radio frequency interference in the 10–250 MHz

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