OPENING THE 21 cm EPOCH OF REIONIZATION WINDOW: MEASUREMENTS OF FOREGROUND ISOLATION WITH PAPER

Pober, Jonathan C.; Parsons, Aaron; Aguirre, James E.; Ali, Zaki S.; Bradley, Richard F.; Carilli, C. L.; DeBoer, D.; Dexter, Matthew R.; Gugliucci, Nicole E.; Jacobs, Daniel; Klima, Patricia J.; MacMahon, Dave; Manley, Jason; Moore, David F.; Stefan, Irina I.; Walbrugh, William P.

doi:10.1088/2041-8205/768/2/l36

Cited by 201 publications

(247 citation statements)

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“…• and featuring the beam response pattern characteristic of PAPER dipole elements (Parsons et al 2008;Pober et al 2012). The PAPER beam response pattern is illustrated in the leftmost panel of Figure 7.…”

Section: Methodsmentioning

confidence: 99%

“…If it is temporally stable, however, it is possible to significantly suppress crosstalk in data by averaging visibilities over a long period (so that the fringing celestial signal washes out) and then subtracting the average complex additive offset from the data. This technique has long been applied to, e.g., PAPER observations (Parsons et al 2010;Pober et al 2013;Jacobs et al 2014;Parsons et al 2014;Ali et al 2015).…”

Section: Minimizing Instrumental Systematics Andmentioning

confidence: 99%

“…The results highlight the power of fringe-rate filtering in 21cm cosmology applications. Given its efficiency, flexibility, and close alignment with the natural observing basis of radio interferometers, we anticipate that fringe-rate filtering may be an important analysis tool for current 21cm experiments, as well as future instruments such as the Hydrogen Epoch of Reionization Array (HERA; Pober et al 2014) and the Square Kilometre Array (SKA; Carilli 2014). …”

Section: 2mentioning

confidence: 99%

“…These differences have led to the design, construction, and usage of new interferometers that only have moderate angular resolution, but are comprised of a large number of receiving elements with wide fields of view operating over a wide bandwidth. Examples of new interferometers that broadly fit some or all of this description include the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER; Parsons et al 2010), the Murchison Widefield Array (MWA; Tingay et al 2013;Bowman et al 2013), the LOw Frequency ARray (LOFAR; van Haarlem et al 2013), the Canadian Hydrogen Intensity Mapping Experiment (CHIME; Bandura et al 2014), the MIT Epoch of Reionization experiment (MITEoR; Zheng et al 2014), the Large Aperture Experiment to Detect the Dark Ages (LEDA; Greenhill & Bernardi 2012), and the Hydrogen Epoch of Reionization Array (HERA; Pober et al 2014). Further deviating from conventional array designs, the PAPER, MITEoR, CHIME, HERA projects have also maximized sensitivity by choosing to place their antenna elements in regular, redundant grids (Parsons 1 Astronomy Dept., U. California, Berkeley, CA 2 Radio Astronomy Lab., U. California, Berkeley, CA 3 Berkeley Center for Cosmological Physics, Berkeley, CA et al 2012a).…”

Section: Introductionmentioning

confidence: 99%

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Optimized Beam Sculpting With Generalized Fringe-Rate Filters

Parsons

Liu

Ali

et al. 2016

ApJ

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We generalize the technique of fringe-rate filtering, whereby visibilities measured by a radio interferometer are re-weighted according to their temporal variation. As the Earth rotates, radio sources traverse through an interferometer's fringe pattern at rates that depend on their position on the sky. Capitalizing on this geometric interpretation of fringe rates, we employ time-domain convolution kernels to enact fringe-rate filters that sculpt the effective primary beam of antennas in an interferometer. As we show, beam sculpting through fringe-rate filtering can be used to optimize measurements for a variety of applications, including mapmaking, minimizing polarization leakage, suppressing instrumental systematics, and enhancing the sensitivity of power-spectrum measurements. We show that fringe-rate filtering arises naturally in minimum variance treatments of many of these problems, enabling optimal visibility-based approaches to analyses of interferometric data that avoid systematics potentially introduced by traditional approaches such as imaging. Our techniques have recently been demonstrated in Ali et al. (2015), where new upper limits were placed on the 21 cm power spectrum from reionization, showcasing the ability of fringe-rate filtering to successfully boost sensitivity and reduce the impact of systematics in deep observations.

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Section: Methodsmentioning

confidence: 99%

Section: Minimizing Instrumental Systematics Andmentioning

confidence: 99%

Section: 2mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Optimized Beam Sculpting With Generalized Fringe-Rate Filters

Parsons

Liu

Ali

et al. 2016

ApJ

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“…Besides LOFAR itself, these new instruments include the recently commissioned LWA (10−88 MHz) (see Kassim et al 2010;Lazio et al 2010;Taylor et al 2012, and examples therein) and MWA (80−300 MHz) (see Rightley et al 2009;Oberoi et al 2011;Bowman et al 2013;Tingay et al 2013b, and examples therein), both of which provide powerful solar observing capabilities. Although not specficially intended for solar observations, the PAPER (see Parsons et al 2010;Stefan et al 2013;Pober et al 2013, for descriptions of the PAPER instrument) operates in the 100−200 MHz range and also provides similar potential capablities. In the Ukraine, the radio telescopes UTR2 (Sidorchuk et al 2005) and URAN2 (Brazhenko et al 2005) also work at low frequencies.…”

Section: Solar Physics and Space Weathermentioning

confidence: 99%

LOFAR: The LOw-Frequency ARray

Haarlem

Wise

Gunst

et al. 2013

A&A

2,021

783

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LOFAR, the LOw-Frequency ARray, is a new-generation radio interferometer constructed in the north of the Netherlands and across europe. Utilizing a novel phased-array design, LOFAR covers the largely unexplored low-frequency range from 10-240 MHz and provides a number of unique observing capabilities. Spreading out from a core located near the village of Exloo in the northeast of the Netherlands, a total of 40 LOFAR stations are nearing completion. A further five stations have been deployed throughout Germany, and one station has been built in each of France, Sweden, and the UK. Digital beam-forming techniques make the LOFAR system agile and allow for rapid repointing of the telescope as well as the potential for multiple simultaneous observations. With its dense core array and long interferometric baselines, LOFAR achieves unparalleled sensitivity and angular resolution in the low-frequency radio regime. The LOFAR facilities are jointly operated by the International LOFAR Telescope (ILT) foundation, as an observatory open to the global astronomical community. LOFAR is one of the first radio observatories to feature automated processing pipelines to deliver fully calibrated science products to its user community. LOFAR's new capabilities, techniques and modus operandi make it an important pathfinder for the Square Kilometre Array (SKA). We give an overview of the LOFAR instrument, its major hardware and software components, and the core science objectives that have driven its design. In addition, we present a selection of new results from the commissioning phase of this new radio observatory.

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Measuring phased‐array antenna beampatterns with high dynamic range for the Murchison Widefield Array using 137 MHz ORBCOMM satellites

et al. 2015

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Detection of the fluctuations in a 21 cm line emission from neutral hydrogen during the Epoch of Reionization in thousand hour integrations poses stringent requirements on calibration and image quality, both of which necessitate accurate primary beam models. The Murchison Widefield Array (MWA) uses phased-array antenna elements which maximize collecting area at the cost of complexity. To quantify their performance, we have developed a novel beam measurement system using the 137 MHz ORBCOMM satellite constellation and a reference dipole antenna. Using power ratio measurements, we measure the in situ beampattern of the MWA antenna tile relative to that of the reference antenna, canceling the variation of satellite flux or polarization with time. We employ angular averaging to mitigate multipath effects (ground scattering) and assess environmental systematics with a null experiment in which the MWA tile is replaced with a second-reference dipole. We achieve beam measurements over 30 dB dynamic range in beam sensitivity over a large field of view (65% of the visible sky), far wider and deeper than drift scans through astronomical sources allow. We verify an analytic model of the MWA tile at this frequency within a few percent statistical scatter within the full width at half maximum. Toward the edges of the main lobe and in the sidelobes, we measure tens of percent systematic deviations. We compare these errors with those expected from known beamforming errors.

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OPENING THE 21 cm EPOCH OF REIONIZATION WINDOW: MEASUREMENTS OF FOREGROUND ISOLATION WITH PAPER

Cited by 201 publications

References 24 publications

Optimized Beam Sculpting With Generalized Fringe-Rate Filters

Optimized Beam Sculpting With Generalized Fringe-Rate Filters

LOFAR: The LOw-Frequency ARray

Measuring phased‐array antenna beampatterns with high dynamic range for the Murchison Widefield Array using 137 MHz ORBCOMM satellites

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