Preliminary sensitivity verification of the SKA-Low AAVS2 prototype

Sokołowski, M.; Broderick, J. W.; Wayth, R. B.; Davidson, David; Tingay, S. J.; Ung, D.; Benthem, P.; Bercigli, M.; Bolli, Pietro; Booler, T.; Chiello, Riccardo; Comoretto, G.; Ninni, Paola Di; Kovaleva, Maria; Macario, G.; Magrok, A.; Mattana, A.; Monari, Jader; Perini, Federico; Pupillo, G.; Schiaffino, Marco; Sutinjo, Adrian; Es, Andre van; Virone, G.; Waterson, M.

doi:10.23919/eucap51087.2021.9410962

Cited by 6 publications

(8 citation statements)

References 11 publications

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“…The Sun is unresolved at all frequencies by the longest baselines of the array and was therefore used as point-like calibration source (similar to previous works 3,6,10 ) . During our observations there was no sign of solar activity either (see https://www.solarmonitor.org/index.php).…”

Section: Observations and Data Processingmentioning

confidence: 99%

“…The difference imaging method is based on the generation and analysis of the differences between each pair of close-in-time images, over which the sky and the calibration do not appreciably change. The image differences should thus, ideally, include just noise (all the astrophysical radio sources and calibration artifacts cancel out, see 3,10 ) . The difference between the two time-step images (Section 3) for each snapshot and each polarization were produced through the MATHS task.…”

Section: Difference Imagingmentioning

confidence: 99%

“…In the control room, optical signals are connected to 16 Tile Processing Modules (TPMs), where different data outputs are produced. For a complete description of the system, signal chain, monitoring and control software, observing modes and data processing, we refer the reader to previous works that provide more details (see 3,4,6,7,10 ).…”

Section: Introductionmentioning

confidence: 99%

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Characterization of the SKA1-Low prototype station Aperture Array Verification System 2

Macario¹,

Pupillo²,

Bernardi³

et al. 2021

Preprint

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The low frequency component of the Square Kilometre Array (SKA1-Low) will be an aperture phased array located at the Murchison Radio-astronomy Observatory (MRO) site in Western Australia. It will be composed of 512 stations, each of them consisting of 256 log-periodic dual polarized antennas, and will operate in the low frequency range (50 MHz -350 MHz) of the SKA bandwidth. The Aperture Array Verification System 2 (AAVS2), operational since late 2019, is the last full-size engineering prototype station deployed at the MRO site before the start of the SKA1-Low construction phase. The aim of this paper is to characterize the station performance through commissioning observations at six different frequencies (55, 70, 110, 160, 230 and 320 MHz) collected during its first year of activities. We describe the calibration procedure, present the resulting all-sky images and their analysis, and discuss the station calibratability and system stability. Using the difference imaging method, we also derive estimates of the SKA1-Low sensitivity for the same frequencies, and compare them to those obtained through electromagnetic simulations across the entire telescope bandwidth, finding good agreement (within 13%). Moreover, our estimates exceed the SKA1-Low requirements at all the considered frequencies, by up to a factor of ∼2.3. Our results are very promising and allow an initial validation of the AAVS2 prototype station performance, which is an important step towards the upcoming SKA-Low telescope construction and science.

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Section: Observations and Data Processingmentioning

confidence: 99%

Section: Difference Imagingmentioning

confidence: 99%

See 1 more Smart Citation

Characterization of the SKA1-Low prototype station Aperture Array Verification System 2

Macario¹,

Pupillo²,

Bernardi³

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…The Sun is unresolved at all frequencies by the longest baselines of the array and was therefore used as a point-like calibration source (similarly to previous works 3,6,11 ). During our observations, there was no sign of solar activity (see Ref.…”

Section: Observations and Data Processingmentioning

confidence: 99%

Characterization of the SKA1-Low prototype station Aperture Array Verification System 2

Macario

Pupillo

Bernardi

et al. 2022

J. Astron. Telesc. Instrum. Syst.

View full text Add to dashboard Cite

The low frequency component of the Square Kilometre Array (SKA1-Low) will be an aperture phased array located at the Murchison Radio-astronomy Observatory (MRO) site in Western Australia. It will be composed of 512 stations, each consisting of 256 log-periodic dual-polarized antennas, and will operate in the low frequency range (50 to 350 MHz) of the SKA bandwidth. The Aperture Array Verification System 2 (AAVS2), operational since late 2019, is the last full-size engineering prototype station deployed at the MRO site before the start of the SKA1-Low construction phase. The aim of this paper is to characterize the station performance through commissioning observations at six different frequencies (55, 70, 110, 160, 230, and 320 MHz) collected during its first year of activities. We describe the calibration procedure, present the resulting all-sky images and their analysis, and discuss the station calibratability and system stability. Using the difference imaging method, we also derive estimates of the SKA1-Low sensitivity for the same frequencies and compare them with those obtained through electromagnetic simulations across the entire telescope bandwidth, finding good agreement (within 13%). Moreover, our estimates exceed the SKA1-Low requirements at all considered frequencies by up to a factor of ∼2.3. Our results are very promising and allow for an initial validation of the AAVS2 prototype station performance, which is an important step toward the coming SKA1-Low telescope construction and science.

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“…In pseudo‐random array the patterns variability increases the complexity of the calibration scheme, which has to account for a different direction‐dependent response for each antenna (S. J. Wijnholds et al., 2019). At low frequencies, the mutual coupling effect can even distort the antenna patterns to the extent that there is a significant loss of sensitivity, particularly at low elevation angles (Di Ninni et al., 2019; Sokolowski et al., 2021). This paper focuses on the relationship between the maximum mutual coupling between antennas and their positions within the AAVS2.0.…”

Section: Introductionmentioning

confidence: 99%

Mutual Coupling Mitigation in Array Dense Regime by an Antenna Distribution Optimization in SKA1‐LOW

et al. 2022

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The Aperture Array Verification System 2.0 is the latest technological demonstrator designed for the Square Kilometer Array radio telescope operating at low frequency (50–350 MHz). This is an aperture phased array, known as a “station” of the radio telescope, with a pseudo‐random distribution of 256 dual polarized log‐periodic antennas. Mutual coupling effects among the antennas are known to produce detrimental effects especially at the lower end of the operating frequency band. This paper presents a relationship between the antennas electromagnetic performance and their physical position inside the station, followed by an identification of the most critical distances and alignment‐angles between antennas. The calibration accuracy of the station and its directivity within the field of view of the radio telescope are recalculated after repositioning ∼20% of the 256 antennas showing clear improvements in dense regime with respect to the actual AAVS2.0 layout.

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Preliminary sensitivity verification of the SKA-Low AAVS2 prototype

Cited by 6 publications

References 11 publications

Characterization of the SKA1-Low prototype station Aperture Array Verification System 2

Characterization of the SKA1-Low prototype station Aperture Array Verification System 2

Characterization of the SKA1-Low prototype station Aperture Array Verification System 2

Mutual Coupling Mitigation in Array Dense Regime by an Antenna Distribution Optimization in SKA1‐LOW

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