The detection by EGRET of 40 active galactic nuclei in high energy gamma rays ahs sparked interest in high energy extragalactic gamma ray astronomy. ... In this thesis I investigate the infrared background, the interactions by which it absorbs gamma rays, and I develop a program that uses monte carlo techniques, as well as suitable approximations to model the effect of these interactions on gamma ray spectra, and discuss the implications for high energy gamma ray astronomy. | ...
metrologia The leap second: its history and possible future R. A. Nelson, D. D. McCarthy , S. Malys, J. Levine, B. Guinot, H. F. Fliegel , R. L. Beard and T. R. Bartholome w Abstract. This paper reviews the theoretica l motivatio n for the leap second in the context of the historica l evolutio n of time measurement . Th e periodic insertio n of a leap second step into th e scale of Coordinate d Universal Time (UTC) necessitates frequent changes in comple x timekeepin g systems an d is currentl y th e
... Twenty-Six Year Monitoring of Water Masers IAU Symposium 242, Alice Springs 1 Contents of the work A sample of H2O maser emission sources has been observed since 1980. ... Rudnitskij et al. ... Twenty-Six Year Monitoring of Water Masers IAU Symposium 242, Alice Springs 4 Maser in a protoplanetary disc (S255) Flux density, Jy S255: H2O line profile 5 February 2002 Radial velocity, LSR, km/s Rudnitskij et al. ... Twenty-Six Year Monitoring of Water Masers IAU Symposium 242, Alice Springs 12 ...
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Ссылки http://www.atnf.csiro.au/research/masermeeting/web_papers/523_Rudnitskij.pdf -- 481.0 Кб -- 26.04.2007 Похожие документы