نتایج جستجو برای: ray astronomy
تعداد نتایج: 318915 فیلتر نتایج به سال:
We describe the highly variable X-ray and UV emission of V458Vul (Nova Vul 2007), observed by Swift between 1 and 422 days after outburst. Initially bright only in the UV, V458Vul became a variable hard X-ray source due to optically thin thermal emission at kT = 0.64 keV with an X-ray band unabsorbed luminosity of 2.3×10 erg s during days 71-140. The X-ray spectrum at this time requires a low F...
X iv :a st ro -p h/ 05 09 89 1v 3 9 N ov 2 00 5 The Progenitors of Short-Hard Gamma-Ray Bursts from an Extended Sample of Events Avishay Gal-Yam, Ehud Nakar, Eran O. Ofek, S. B. Cenko, S. R. Kulkarni, A. M. Soderberg, F. Harrison Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA91125 D. B. Fox Department of Astronomy & Astrophysics, 525 Davey Labor...
Day-Scale Variability of 3C 279 and Searches for Correlations in Gamma-Ray, X-Ray, and Optical Bands
Light curves of 3C 279 are presented in optical (R-band), X-rays (RXTE/PCA), and γ rays (CGRO/EGRET) for 1999 Jan–Feb and 2000 Jan–Mar. During both of those epochs the γ-ray levels were high, and all three observed bands demonstrated substantial variation, on time scales as short as one day. Correlation analyses provided no consistent pattern, although a rather significant optical/γ-ray correla...
the islamic astronomy including the persian astronomy was thoroughly introduced into india from the 14th century ad or so. firstly, the astrolabe was introduced at the time of f?r?z sh?h tughluk?, and a sanskrit work entitled yantra-r?ja (1370 ad) was composed by mahendra s?ri. at that time, some sanskrit astronomical (or astrological) works were also translated into persian. the astrolabe beca...
We have made a multiwavelength study of the overlapping error boxes of the unidentified γ-ray sources TeV J2032+4130 and 3EG J2033+4118 in the direction of the Cygnus OB2 association (d = 1.7 kpc) in order to search for a pointsource counterpart of the first unidentified TeV source. Optical identifications and spectroscopic classifications for the brighter X-ray sources in ROSAT PSPC and Chandr...
We briefly review capabilities and requirements for future instrumentation in UVand X-ray astronomy that can contribute to advancing our understanding of the diffuse, highly ionised intergalactic medium.
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