All posts under category "Astrophysics / Astro-Ph.IM"
Transmission spectroscopy of Earth-like exoplanets is a potential tool for habitability screening. Transiting planets are present-day 'Rosetta Stones' for understanding extrasolar planets because they offer the possibility to characterize giant planet atmospheres and should provide an access to biom
Today, the motion of spacecraft is still described by the classical Newtonian equations of motion plus some relativistic corrections. This approach might become cumbersome due to the increasing precision required. We use the Relativistic Motion Integrator (RMI) approach to numerically integrate the
The HAWC gamma ray observatory, to be constructed at Sierra Negra, Puebla in Mexico, is a large array of water Cherenkov detectors sited at an elevation of 4100 m, which has been optimized for gamma/hadron discrimination of the primary cosmic rays in the TeV energy range. It is based on the Milagro
The energy estimation procedures employed by different groups, for determining the energy of the primary $gamma$-ray using a single atmospheric Cherenkov imaging telescope, include methods like polynomial fitting in SIZE and DISTANCE, general least square fitting and look-up table based interpolatio
The production of acoustic signals from the interactions of ultra-high energy (UHE) cosmic ray neutrinos in water and ice has been studied. A new computationally fast and efficient method of deriving the signal is presented. This method allows the implementation of up to date parameterisations of ac
The observations of Mars by the CRISM and OMEGA hyperspectral imaging spectrometers require correction for photometric, atmospheric and thermal effects prior to the interpretation of possible mineralogical features in the spectra. Here, we report on a simple, yet non-trivial, adaptation to the commo
Context. The synthesis of water is one necessary step in the origin and development of life. It is believed that pristine water is formed and grows on the surface of icy dust grains in dark interstellar clouds. Until now, there has been no experimental evidence whether this scenario is feasible or n
Montage is a portable software toolkit for constructing custom, science-grade mosaics by composing multiple astronomical images. The mosaics constructed by Montage preserve the astrometry (position) and photometry (intensity) of the sources in the input images. The mosaic to be constructed is specif
Using a bistatic radar echo sounding (RES) system developed for calibration of the RICE particle astrophysics experiment at the South Pole, we have studied radio frequency (RF) reflections off the bedrock. The total propagation time of ~ns-duration, vertically (z-) broadcast radio signals, as a func
The Large APEX Bolometer Camera, LABOCA, has been commissioned for operation as a new facility instrument t the Atacama Pathfinder Experiment 12m submillimeter telescope. This new 295-bolometer total power camera, operating in the 870 micron atmospheric window, combined with the high efficiency of A
We advocate support of research aimed at developing alternatives to the photomultiplier tube for photon detection in large astroparticle experiments such as gamma-ray and neutrino astronomy, and direct dark matter detectors. Specifically, we discuss the development of large area photocathode microch
We propose the timescale-resolved spectroscopy (TRS) as a new method to combine the timing and spectral study. TRS is based on the time domain power spectrum and reflects the variable amplitudes of spectral components on different timescales. We produce the TRS with the RXTE PCA data for Cyg X-1 and
This is a scientific strategy for the detection and characterization of extrasolar planets; that is, planets orbiting other stars. As such, it maps out over a 15-year horizon the techniques and capabilities required to detect and measure the properties of planets as small as Earth around stars as la
This paper conveys the outcomes of what results to be the first, though initial, overview of commenting platforms and related 2.0 resources born within and for the astrophysical community (from 2004 to 2016). Experiences were added, mainly in the physics domain, for a total of 22 major items, includ
Current AMR simulations require algorithms that are highly parallelized and manage memory efficiently. As compute engines grow larger, AMR simulations will require algorithms that achieve new levels of efficient parallelization and memory management. We have attempted to employ new techniques to ach
The detection of photons above 10 keV through MeV and GeV energies is challenging due to the penetrating nature of the radiation, which can require large detector volumes, resulting in correspondingly high background. In this energy range, most detectors in space are either scintillators or solid-st
From an anthropological point of view, the whole concept of a 'path of progress' in astronomical discovery is anathema, since it implicitly downgrades other cultural perspectives, such as the many 'indigenous cosmologies' that still exist in the modern world. By doing so, one risks provoking those w
This document describes the minimum interface that a (SOAP- or REST-based) web service requires to participate in the IVOA. Note that this is not required of standard VO services developed prior to this specification, although uptake is strongly encouraged on any subsequent revision. All new standar
The request driven way of deriving data in Astro-WISE is extended to a query driven way of visualization. This allows scientists to focus on the science they want to perform, because all administration of their data is automated. This can be done over an abstraction layer that enhances control and f
We propose a new algorithm for solving a system of two nonlinear transcendental equations with two complex variables based on the Muller algorithm. The two-dimensional Muller algorithm is tested on systems of different type and is found to work comparably to Newton's method and Broyden's method in m
Modern satellite based experiments are often very complex real-time systems, composed by flight and ground segments, that have challenging resource related constraints, in terms of size, weight, power, requirements for real-time response, fault tolerance, and specialized input/output hardware-softwa
A new method is proposed to divide a spherical surface into equal-area cells. The method is based on dividing a sphere into several latitudinal bands of near-constant span with further division of each band into equal-area cells. It is simple in construction and provides more uniform latitude step b
We present an analytical unified representation for 22 equations of state (EoS) of dense matter in neutron stars. Such analytical representations can be useful for modeling neutron star structure in modified theories of gravity with high order derivatives.
The classical method for measure the Earth-Sun distance is due to Aristarchus and it is based upon the measure of the angle Moon-Earth-Sun when the Moon is exactly in quadrature. Such an angle is only 9 arcminutes smaller than 90 degrees, and it is very difficult to evaluate, being necessary to look
A simple technique of measurement of seeing in daytime and nighttime, based upon drift-scan observations, is presented, along with observational examples. This experience can be repeated easily in classroom contexts.
Over the past 3 years, Auckland University of Technology has established the first radio astronomical observatory in New Zealand, which, because of its remote geographic location, has quickly become a member of a number of international VLBI networks, in particular the IVS and the LBA. Not only has
Extraterrestrial technology may exist in the Solar System without our knowledge. This is because the vastness of space, combined with our limited searches to date, implies that any remote unpiloted exploratory probes of extraterrestrial origin would likely remain unnoticed. Here we develop a probabi
Searches for point sources of astrophysical neutrinos and related measurements: Searches for steady and time-variable sources; Follow-up programs; AGNs; GRBs; Moon shadow; Submitted papers to the 32nd International Cosmic Ray Conference, Beijing 2011.
Cosmic rays and related measurements: IceTop overview; IceTop calibration; Cosmic ray composition; Air shower measurements; Studies of cosmic ray muons; Studies of PeV gamma rays; Cosmic ray anisotropy; Forbush decrease; Submitted papers to the 32nd International Cosmic Ray Conference, Beijing 2011.
Exotic particle searches: WIMPs annihilating in the Sun, in the galactic center, in nearby dwarf galaxies; magnetic monopoles; Submitted papers to the 32nd International Cosmic Ray Conference, Beijing 2011.
Two methods for the determination of extrema timings and their uncertainties appropriate for the analysis of time series of variable stars using matrix calculus are presented. The method I is suitable for determination of times of extrema of non-periodical variables or objects, whose light curves va
A general model is proposed to explain the relation between the extrasolar planets (or exoplanets) detected until June 2008 and the main characteristics of their host stars through statistical techniques. The main goal is to establish a mathematical relation among the set of variables which better d
Numerical integration of the differential equations of light propagation in the Schwarzschild metric shows that in some extreme situations relevant for practical observations (e.g. for Gaia) the well-known standard post-Newtonian formula for the boundary problem has an error up to 16 muas. The aim o
The Anti Coincidence Shield (ACS) of the INTEGRAL SPI instrument provides an excellent sensitivity for the detection of Gamma Ray Bursts (GRBs) above ~ 75keV, but no directional and energy information is available. We studied the ACS response by using GRBs with known localizations and good spectral
Bibliometric indicators, citation counts and/or download counts are increasingly being used to inform personnel decisions such as hiring or promotions. These statistics are very often misused. Here we provide a guide to the factors which should be considered when using these so-called quantitative m
In this paper we analyze the maximum entropy image deconvolution. We show that given the Lagrange multiplier a closed form can be obtained for the image parameters. Using this solution we are able to provide better understanding of some of the known behavior of the maximum entropy algorithm. The sol
We obtain an expression for the probability density function (PDF) of partially developed speckles formed by light with an arbitrary degree of polarization. From the probability density we calculate the detection threshold corresponding to the 5sigma confidence level of a normal distribution. We sho
We present results of a study of the localization capability of Fermi-LAT, using a large set of blazars with precise radio locations. Since the width of the PSF decreases with energy, the performance is typically dominated by a few high energy photons, so it is important to properly characterize the
Enter keywords to search articles