相关论文: An improvement of the BeppoSAX LECS and MECS posit…

We present 3 methods for the subtraction of non-cosmic and unresolved cosmic backgrounds observed by the Low-Energy Concentrator Spectrometer (LECS) on-board BeppoSAX. Removal of these backgrounds allows a more accurate modeling of the…

The spectrum of the 1.0-8.0 keV cosmic X-ray background (CXB) at galactic latitudes > 25 degrees has been measured using the BeppoSAX LECS and MECS instruments. The spectrum is consistent with a power-law of photon index 1.40 +/- 0.04 and…

We present an empirical correction of sky coordinates of X-ray photons obtained with the XIS aboard the Suzaku satellite to improve the source position accuracy and restore the point-spread function (PSF). The XIS images are known to have…

At a flux limit of ~10^(-11) erg/cm2/s in the 20-100 keV band, the PDS instrument on-board BeppoSAX offers the opportunity to study the extragalactic sky with an unprecedented sensitivity. In this work we report on the results of a search…

A steradian of the southern sky has been imaged at 151.5 MHz using the Mauritius Radio Telescope (MRT). These images show systematics in positional errors of sources when compared to source positions in the Molonglo Reference Catalogue…

Accurate alignment of the radio and optical celestial reference frames requires detailed understanding of physical factors that may cause offsets between the positions of the same object measured in different spectral bands. Opacity in…

Optical positions from the SuperCOSMOS Sky Survey have been compared in detail with accurate radio positions that define the second realisation of the International Celestial Reference Frame (ICRF2). The comparison was limited to the IIIaJ…

We present improvements to the pointing accuracy of the South Pole Telescope (SPT) using machine learning. The ability of the SPT to point accurately at the sky is limited by its structural imperfections, which are impacted by the extreme…

We present new BeppoSAX LECS and MECS observations, covering the energy range 0.1 - 10 keV (observer's frame), of four BL Lacertae objects selected from the 1 Jy sample. All sources display a flat (alpha_x ~ 0.7) X-ray spectrum, which we…

(Abridged) Spectral and time variability analysis of the region of the hard X-ray transient EXS 1737.9-2952 near the Galactic Centre (GC), using data from the Narrow Field Instruments of BeppoSAX is reported. The main results are the MECS…

Current measurements of the weak lensing signal induced by large scale structure provide useful constraints on a range of cosmological parameters. However, the ultimate succes of this technique depends on the accuracy with which one can…

We deal with the attempts to measure the Lense-Thirring effect with the Satellite Laser Ranging (SLR) technique applied to the existing LAGEOS and LAGEOS II terrestrial satellites and to the recently approved LARES spacecraft.The first…

Aims. The knowledge of the orbits and origins derived from meteors is important for the study of meteoroids and of the early solar system. With an increase in nano-satellite projects dedicated to Earth observations or directly to meteor…

Ground and in flight calibrations of the MECS experiment on board Beppo-SAX have demonstrated that this is currently the best X-ray imaging experiment above 3 keV. The MECS on-axis PSF has a half power radius of about 1 arcmin. Moreover due…

We report the current status of the analysis of the MECS background using the entire dataset of the BeppoSAX Science performance Verification Phase. We have collected 360 ks of dark Earth instrumental background, 470 ks of bright Earth…

The goal of the recently approved space-based LARES mission is to measure the general relativistic Lense-Thirring effect in the gravitational field of the spinning Earth at a repeatedly claimed 1% accuracy by combining its node Omega with…

Published analyses of very long baseline interferometry (VLBI) data for the sources included in the third International Celestial Reference Frame (ICRF3) catalog have revealed object-specific, excess astrometric variability and…

The first half of this paper explores the origin of systematic biases in the measurement of weak gravitational lensing. Compared to previous work, we expand the investigation of PSF instability and fold in for the first time the effects of…

The complete 10-year survey from the Large Synoptic Survey Telescope (LSST) will image $\sim$ 20,000 square degrees of sky in six filter bands every few nights, bringing the final survey depth to $r\sim27.5$, with over 4 billion well…

Accurate photometric redshifts are among the key requirements for precision weak lensing measurements. Both the large size of the Sloan Digital Sky Survey (SDSS) and the existence of large spectroscopic redshift samples that are…