Search results for "Angular resolution"
showing 10 items of 65 documents
Estimating the angular resolution of tracks in neutrino telescopes based on a likelihood analysis
2004
A semianalytic method to estimate the angular resolution of tracks, that have been reconstructed by a likelihood approach, is presented. The optimal choice of coordinate systems and resolution parameters, as well as tests of the method are discussed based on an application for a neutrino telescope.
Feasibility of 1 arcmin resolution gamma-ray air-Čerenkov multiple telescope experiment
1995
Abstract In this paper we discuss the feasibility of a ground based detector exploiting the technique of Cerenkov light stereo imaging of air showers for the detection of discrete cosmic sources of γ-rays with energy threshold of 100 GeV, angular resolution (HWHM) of 1 arcmin ( 1 3 mrad), cosmic ray background rejection ≥ 99%. This experiment will make possible a deep survey of the sky with sensitivity of 1 100 of the Crab in 45 h of exposure.
The X-ray Integral Field Unit (X-IFU) for Athena
2014
Athena is designed to implement the Hot and Energetic Universe science theme selected by the European Space Agency for the second large mission of its Cosmic Vision program. The Athena science payload consists of a large aperture high angular resolution X-ray optics (2 m2 at 1 keV) and twelve meters away, two interchangeable focal plane instruments: the X-ray Integral Field Unit (X-IFU) and the Wide Field Imager. The X-IFU is a cryogenic X-ray spectrometer, based on a large array of Transition Edge Sensors (TES), oering 2.5 eV spectral resolution, with approximately 5" pixels, over a field of view of 5' in diameter. In this paper, we present the X-IFU detector and readout electronics princi…
The mirror module design for the cryogenic x-ray imaging spectrometer on-board ORIGIN
2011
ORIGIN is a medium size high-energy mission concept submitted to ESA in response to the Cosmic Vision call issued on July 2010. The mission will investigate the evolution of the Universe by performing soft X-ray high resolution spectroscopic measurements of metals formed in different astrophysical environments, from the first population III stars at z > 7 to the present large scale structures. The main instrument on-board ORIGIN will be a large format array of TES X-ray micro-calorimeters covering a FOV of 30' at the focal plane of a grazing incidence optical module with a focal length of 2.5 m and an angular resolution of 30'' HEW at 1 keV. We present the optical module design which is bas…
Expansion of SN 1993J: New λλ6 and 13 cm images
1997
Abstract Radio supernovae are rare events among supernovae, usually taking place in distant galaxies. In recent years, great progress has been made in the study of radio supernovae with high angular resolution, due to advances in the VLBI technique and to the lucky occurrence of the powerful supernova SN 1993J in M81 only 3.6 Mpc distant. Its spatial structure has been unveiled and its expansion rate determined at 3.6 cm. Here we present new preliminary VLBI results on the expansion of this supernova at 6 and 13 cm. We resolve the shell at both wavelengths. The size estimates at 6 cm indicate a lower expansion rate than previously estimated. This may be the first evidence of deceleration.
The limb-brightened jet of M87 down to 7 Schwarzschild radii scale
2018
M87 is one of the nearest radio galaxies with a prominent jet extending from sub-pc to kpc-scales. Because of its proximity and large mass of the central black hole, it is one of the best radio sources to study jet formation. We aim at studying the physical conditions near the jet base at projected separations from the BH of $\sim7-100$ Schwarzschild radii ($R_{\rm sch}$). Global mm-VLBI Array (GMVA) observations at 86 GHz ($\lambda=3.5\,$mm) provide an angular resolution of $\sim50\mu$as, which corresponds to a spatial resolution of only $7~R_{\rm sch}$ and reach the small spatial scale. We use five GMVA data sets of M87 obtained during 2004--2015 and present new high angular resolution VL…
JEM–X: The X-ray monitor aboard INTEGRAL
2003
The JEM-X monitor provides X-ray spectra and imaging with arcminute angular resolution in the 3 to 35 keV band. The good angular resolution and the low energy response of JEM-X plays an important role in the identification of gamma ray sources and in the analysis and scientific interpretation of the combined X-ray and gamma ray data. JEM-X is a coded aperture instrument consisting of two identical, coaligned telescopes. Each of the detectors has a sensitive area of 500 cm 2 , and views the sky through its own coded aperture mask. The two coded masks are inverted with respect to each other and provides an angular resolution of 3 0 across an eective field of view of about 10 diameter.
Observability of γ-ray pulsars
1978
PULSARS seem to play a major role as γ-ray emitters. Of the 13 objects listed in the first COS B catalogue1 the two brightest, CG185-5 and CG263-2, have been identified with the Crab (PSR0531+21) and Vela (PSR0833–;45) pulsars respectively. This privileged role of pulsars as identified γ-ray sources could be simply related to observational reasons: in fact, because of the poor angular resolution intrinsic to the γ-ray telescopes, the only possibility of identification for individual sources is the time structure of the emission, and the periodical pattern of pulsars is particularly suited. On the other hand, for PSR0531+21 and PSR0833−45, the observed pulsed energy release is essentially in…
Searching for localized cosmic particle sources with an unbinned maximum likelihood approach
2006
Abstract An unbinned method to search for localized cosmic particle sources is presented. The expected source shape, the measured background shape, and the estimated angular resolution of individual tracks are used to construct a likelihood function. Estimates of the flux, the position and—in particular—the significance of a source can be readily obtained. A full confidence belt construction to deduce flux limits is presented. General statistical issues when searching for sources of unknown position are discussed.
Imaging test setup for the coded-mask /spl gamma/-ray spectrometer SPI
2001
The European Space Agency's International Gamma-Ray Astrophysics Laboratory (INTEGRAL) will be launched in 2002. One of its two main instruments is the spectrometer SPI. It uses 19 HPGe detectors to observe the sky in the energy range of 20 keV to 8 MeV with a resolution of /spl Delta/E/E/spl ap/0.2%. Directional information is obtained using a coded mask. The expected angular resolution is about 20, The SPI imaging test setup (SPITS) was built at the Max-Planck-Institut fur Extraterrestische Physik, Germany, to allow experimental verification of the imaging properties of SPI. SPITS consists of a coded hexagonal uniformly redundant array (HURA) mask and two germanium detectors. The mask is …