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The estimation of the direction of electromagnetic (EM) waves from a radio source using electrically short antennas is one of the challenging problems in the field of radio astronomy. In this paper we have developed an algorithm which performs better in direction and polarization estimations than the existing algorithms. Our proposed algorithm Snapshot Averaged Matrix Pencil Method (SAM) is a modification to the existing Matrix Pencil Method (MPM) based Direction of Arrival (DoA) algorithm. In general, MPM estimates DoA of the incoherent EM waves in the spectra using unitary transformations and least square method (LSM). Our proposed SAM modification is made in context to the proposed Space Electric and Magnetic Sensor (SEAMS) mission to study the radio universe below 16 MHz. SAM introduces a snapshot averaging method to improve the incoherent frequency estimation thereby improving the accuracy of DoA estimation. It can also detect polarization to differentiate between Right Hand Circular Polarlization (RHCP), Right Hand Elliptical Polarlization (RHEP), Left Hand Circular Polarlization (LHCP), Left Hand Elliptical Polarlization (LHEP) and Linear Polarlization (LP). This paper discusses the formalism of SAM and shows the initial results of a scaled version of a DoA experiment at a resonant frequency of ∼ 72 MHz. [ABSTRACT FROM AUTHOR]

The Polarized Instrument for Long-wavelength Observation of the Tenuous interstellar medium (PILOT) is a balloon-borne experiment that aims to measure the polarized emission of thermal dust at a wavelength of 240µm (1.2 THz). The PILOT experiment flew from Timmins, Ontario, Canada in 2015 and 2019 and from Alice Springs, Australia in April 2017. The in-flight performance of the instrument during the second flight was described in [1]. In this paper, we present data processing steps that were not presented in [1] and that we have recently implemented to correct for several remaining instrumental effects. The additional data processing concerns corrections related to detector cross-talk and readout circuit memory effects, and leakage from total intensity to polarization. We illustrate the above effects and the performance of our corrections using data obtained during the third flight of PILOT, but the methods used to assess the impact of these effects on the final science-ready data, and our strategies for correcting them will be applied to all PILOT data. We show that the above corrections, and in particular that for the intensity to polarization leakage, which is most critical for accurate polarization measurements with PILOT, are accurate to better than 0.4% as measured on Jupiter during flight#3. [ABSTRACT FROM AUTHOR]

The Polarized Instrument for Long-wavelength Observation of the Tenuous interstellar medium (PILOT) is a balloon-borne experiment that aims to measure the polarized emission of thermal dust at a wavelength of 240 µm (1.2 THz). A first PILOT flight of the experiment took place from Timmins, Ontario, Canada, in September 2015 and a second flight took place from Alice Springs, Australia in April 2017. In this paper, we present the inflight performance of the instrument. Here we concentrate on the instrument performance as measured during the second flight, but refer to the performance observed during the first flight, if it was significantly different. We present a short description of the instrument and the flights. We measure the time constants of the detectors using the decay of the observed signal during flight following high energy particle impacts (glitches) and switching off the instrument's internal calibration source. We use these time constants to deconvolve the timelines and analyze the optical quality of the instrument as measured on planets. We then analyze the structure and polarization of the instrumental background. We measure the detector response flat field and its time variations using the signal from the residual atmosphere and from the internal calibration source. Finally, we analyze the spectral and temporal properties of the detector noise. The inflight performance is found to be satisfactory and globally in line with expectations from ground calibrations. We conclude by assessing the expected inflight sensitivity of the instrument in light of the measured inflight performance. [ABSTRACT FROM AUTHOR]

Future cosmology space missions will concentrate on measuring the polarization of the Cosmic Microwave Background, which potentially carries invaluable information about the earliest phases of the evolution of our universe. Such ambitious projects will ultimately be limited by the sensitivity of the instrument and by the accuracy at which polarized foreground emission from our own Galaxy can be subtracted out. We present the PILOT balloon project, which aims at characterizing one of these foreground sources, the polarized continuum emission by dust in the diffuse interstellar medium. The PILOT experiment also constitutes a test-bed for using multiplexed bolometer arrays for polarization measurements. This paper presents the instrument and its expected performances. Performance measured during ground calibrations of the instrument and in flight will be described in a forthcoming paper. [ABSTRACT FROM AUTHOR]

Complementary to the conventional dish radio telescopes, aperture arrays provide a technically attractive approach to achieve a large field of view and flexibility in observational parameters e.g. Sky area vs. bandwidth. Designs of both aperture array elements and overall geometry for the SKA Mid Frequency Aperture Array are presented here, together with resulting trade-offs. The paper reports the latest developments of global efforts on the front-end design of Mid-Frequency Aperture Array, not attempting to make technology selections, as the priority of sciences and the time for implementing Mid-Frequency Aperture Array is yet to be fully confirmed. Different on-going front-end solutions are introduced, particularly crossed ring antenna array with a planar structure is explored in more detail as it is less known in the community. Key performances of the candidate front-end technologies are addressed by examining the prototypes. The objective of the collaborative study is to increase technology readiness for implementation of Mid-Frequency Aperture Array in the future. [ABSTRACT FROM AUTHOR]

Many different methods exist for reducing data obtained when an astronomical source is studied with a two-channel polarimeter, such as a Wollaston prism system. This paper presents a rigorous method of reducing the data from raw aperture photometry, and evaluates errors both by a statistical treatment, and by propagating the measured sky noise from each frame. The reduction process performs a hypothesis test for the presence of linear polarization. The probability of there being a non-zero polarization is obtained, and the best method of obtaining the normalized Stokes Parameters is discussed. Point and interval estimates are obtained for the degree of linear polarization, which is subject to positive bias; and the polarization axis is found. [ABSTRACT FROM AUTHOR]

The Polarized Instrument for Long-wavelength Observation of the Tenuous interstellar medium ( PILOT) is a balloon-borne astronomy experiment designed to study the linear polarization of thermal dust emission in two photometric bands centred at wavelengths 240 μm (1.2 THz) and 550 μm (545 GHz), with an angular resolution of a few arcminutes. Several end-to-end tests of the instrument were performed on the ground between 2012 and 2014, in order to prepare for the first scientific flight of the experiment that took place in September 2015 from Timmins, Ontario, Canada. This paper presents the results of those tests, focussing on an evaluation of the instrument's optical performance. We quantify image quality across the extent of the focal plane, and describe the tests that we conducted to determine the focal plane geometry, the optimal focus position, and sources of internal straylight. We present estimates of the detector response, obtained using an internal calibration source, and estimates of the background intensity and background polarization. [ABSTRACT FROM AUTHOR]

We introduce new observables of the cosmic microwave background radiation, which can be measured through the detection of high order modes excited within an antenna feed system, coherently combined with those currently detected by space observatories. The use of such observables could potentially further constrain the validity of cosmological theories. [ABSTRACT FROM AUTHOR]

Fabrication of an optical dual-beam spectropolarimeter as an add-on facility to an existing astronomical spectrograph at the Vainu Bappu Telescope is described. The polarimetric optics consists of a superachromatic Pancharatnam design half-wave plate and a modified Glan-Taylor polarizing beam splitter. Instrumental response, calibration and characterization of the system are presented. Performance of the spectropolarimeter has been assessed based on the results of observations of polarized and unpolarized standard stars. The attainable accuracy of the instrument is found to be dependent on the S/N of the data. The present data set yields an accuracy of ∼ ±0.5% at 4000 Å and ∼ ±0.3% at 7500 Å, at a spectral resolution of ∼7.2 Å. Analysis of spectropolarimetric data is systematically covered for removal of instrumental errors. The spectropolarimetric reduction software (SPRS), extremely versatile, user friendly and compatible with the IRAF image processing package, was developed for reducing spectropolarimetric data. The empirical relation by Serkowski ( IAU Symposium 52, Interstellar Dust and Related Topics, J. M. Greenberg and H. C. van de Hulst (eds.), Dordrecht, Reidel, 1975, p. 145) for wavelength dependence of polarization due to interstellar medium has been fitted to the data for the star HD 43384 (9 Gem). Our result shows a polarization larger by 0.49% from Hsu and Berger ( ApJ 262, 1982, 732). We attribute this difference to the long term variation in P for this star. [ABSTRACT FROM AUTHOR]