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We have conducted a photometric monitoring program of 3 field late-L brown dwarfs looking for evidence of non-axisymmetric structure or temporal variability in their photospheres. The observations were performed using Spitzer/IRAC 4.5 and 8…

One of the aims of next generation optical interferometric instrumentation is to be able to make use of information contained in the visibility phase to construct high dynamic range images. Radio and optical interferometry are at the two…

We describe a "spatio-spectral" deconvolution algorithm for wide-band imaging in radio interferometry. In contrast with the existing multi-frequency reconstruction algorithms, the proposed method does not rely on a model of the…

天体物理仪器与方法 · 物理学 2016-03-01 André Ferrari , Jérémy Deguignet , Chiara Ferrari , David Mary , Antony Schutz , Oleg Smirnov

We present the first wide area (19 deg$^2$), deep ($\approx120-150$ {\mu}Jy beam$^{-1}$), high resolution ($5.6 \times 7.4$ arcsec) LOFAR High Band Antenna image of the Bo\"otes field made at 130-169 MHz. This image is at least an order of…

We report on an air-spaced virtually imaged phased array (VIPA) spectrometer that resolves the modes of a mid-infrared frequency comb with a repetition rate of 250 MHz, without an optical filter cavity. With a record spectral resolution of…

光学 · 物理学 2026-04-02 Ibrahim Sadiek , Norbert Lang , Jean-Pierre H. van Helden

LOFAR is the only radio telescope that is presently capable of high-sensitivity, high-resolution (<1 mJy/b and <15") observations at ultra-low frequencies (<100 MHz). To utilise these capabilities, the LOFAR Surveys Key Science Project is…

Many scientific deliverables of the next generation low frequency radio telescopes require high dynamic range imaging. Next generation telescopes under construction indeed promise at least a ten-fold increase in the sensitivity compared…

天体物理仪器与方法 · 物理学 2009-06-03 S. Bhatnagar

The Large Area Telescope (LAT) instrument onboard GLAST offers a tremendous opportunity for future blazar studies. In order to fully benefit from its capabilities and to maximize the scientific return from the LAT, it is of great importance…

天体物理学 · 物理学 2009-06-23 L. Fuhrmann , J. A. Zensus , T. P. Krichbaum , E. Angelakis , A. C. S. Readhead

With ever increasing data rates produced by modern radio telescopes like LOFAR and future telescopes like the SKA, many data processing steps are overwhelmed by the amount of data that needs to be handled using limited compute resources.…

天体物理仪器与方法 · 物理学 2020-03-18 Sarod Yatawatta

The effects of the antenna far-field power pattern limits the imaging performance of modern wide-bandwidth, high-sensitivity interferometric radio telescopes. Given a model for the aperture illumination pattern (AIP) of the antenna,…

天体物理仪器与方法 · 物理学 2017-12-11 Preshanth Jagannathan , S. Bhatnagar , W. Brisken , A. R. Taylor

We have undertaken a nearly simultaneous optical/UV and X-ray variability study of the flat spectrum radio quasar, 3C 273 using data available from the XMM$-$Newton satellite mission from June 2000 to July 2012. Here we focus on the…

星系天体物理 · 物理学 2015-06-02 Nibedita Kalita , Alok C. Gupta , Paul J. Wiita , Jai Bhagwan , Kalpana Duorah

Low-frequency radio surveys allow in-depth studies and new analyses of classes of sources previously known and characterised only in other bands. In recent years, low radio frequency observations of blazars have been available thanks to new…

星系天体物理 · 物理学 2020-01-08 Daniele d'Antonio , Marcello Giroletti , Gabriele Giovannini , Alessandro Maini

Fast and broadband spectrum sensing is an essential component in cognitive radio systems, intelligent transportation systems, electronic warfare systems, etc. However, traditional electronic-based solutions have a trade-off among the…

光学 · 物理学 2024-09-25 Taixia Shi , Chi Jiang , Chulun Lin , Fangyi Yang , Yiqing Liu , Fangzheng Zhang , Yang Chen

Efficient ion-photon coupling is an important component for large-scale ion-trap quantum computing. We propose that arrays of phase Fresnel lenses (PFLs) are a favorable optical coupling technology to match with multi-zone ion traps. Both…

量子物理 · 物理学 2011-01-25 E. W. Streed , B. G. Norton , J. J. Chapman , D. Kielpinski

This paper presents the first high-resolution and high-sensitivity study of the radio properties of optically selected type~2 quasars. We used the Very Large Array at 8.4 GHz to observe 59 sources drawn from the Sloan Digital Sky Survey…

宇宙学与河外天体物理 · 物理学 2015-05-14 Dharam Vir Lal , Luis C. Ho

In the frame of the Astronomical Validation activities for the 64m Sardinia Radio Telescope, we performed 5-22 GHz imaging observations of the complex-morphology supernova remnants (SNRs) W44 and IC443. We adopted innovative observing and…

高能天体物理现象 · 物理学 2016-09-14 E. Egron , A. Pellizzoni , S. Loru , M. N. Iacolina , M. Marongiu , S. Righini , S. Mulas , G. Murtas , M. Bachetti , R. Concu , A. Melis , A. Trois , R. Ricci , M. Pilia

This document describes the general astronomical capabilities of the LOw Frequency ARray (LOFAR). The frequency range covered by LOFAR is split into two bands denoted as low band (LB, 10 - 80 MHz) and high band (HB, 120 - 240 MHz). LOFAR…

天体物理仪器与方法 · 物理学 2013-08-23 R. J. Nijboer , M. Pandey-Pommier , A. G. de Bruyn

Continuum reverberation mapping probes the sizescale of the optical continuum-emitting region in active galactic nuclei (AGN). Through 3 years of multiwavelength photometric monitoring in the optical with robotic observatories, we perform…

We report characterization results for an engineering prototype of a next-generation low-frequency radio astronomy array. This prototype, which we refer to as the Aperture Array Verification System 0.5 (AAVS0.5), is a sparse pseudo-random…

We detail new techniques for analysing ionospheric activity, using Epoch of Reionisation (EoR) datasets obtained with the Murchison Widefield Array (MWA), calibrated by the `Real-Time System' (RTS). Using the high spatial- and…

天体物理仪器与方法 · 物理学 2017-08-30 C. H. Jordan , S. Murray , C. M. Trott , R. B. Wayth , D. A. Mitchell , M. Rahimi , B. Pindor , P. Procopio , J. Morgan
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