... U. Amsterdam Explanation: The GRB distance scale controversy may have just ended with a flash . Gamma Ray Bursts (GRBs) are powerful explosions occurring in seemingly random positions on the sky. ... There they found a faint but variable optical source : a potential counterpart to the gamma-ray burst that was getting brighter. Most importantly, continued scrutiny showed that this optical transient had absorption lines with a redshift of about 0.8 - the distance scale of galaxies and quasars . ...

Existing studies of the atomic hydrogen gas content in distant galaxies, through the absorption of the 21-cm line, often infer that the total column density is anti-correlated with the linear extent of the background radio source. We investigate this interpretation, by dissecting the various parameters from which the column density is derived, and find that the relationship is driven primarily by the observed optical depth, which, for a given absorber size, is anti-correlated with the linear size. ...

... May 13, 1997 . Optical Transient Near GRB970508 Shows Distant Redshift . ... Explanation: The GRB distance scale controversy may have just ended with a flash . ... Most importantly, continued scrutiny showed that this optical transient had absorption lines with a redshift of about 0.8 - the distance scale of galaxies and quasars . ... Above is a "negative" image of the GRB970508 field , located near the north celestial pole, taken hours after the initial flash of gamma rays. ... About APOD > . ...

... Galaxy Evolution home . ... The origin and evolution of radio sources . Radio sources and their environments . ... We are investigating how this interaction effects galaxy evolution in general as well as the feedback effect of the radio source on its host galaxy and AGN. ... One direct observational manifestation of this interaction is the existence of extended regions of emission-line gas which show a clear spatial relationship to the radio source itself. ...

... The search for distant objects which can be both galaxies and quasars is one of the most important problems of observational astrphysics, because it allows one to determine cosmological parameters connected with the time of appearence and evolution of stellar systems, large scale structure of the Universe. ... Radio galaxies are important objects to be studied because they are sources of infrared-optical-ultraviolet continuum, emission lines and continual radio emission. ...

Next: Catalog Construction Up: Observations and Analysis Previous: Source Detections . ... It was assumed that the highest signal gives the most likely position of the source. ... Comparing the summed map with the maps from the individual energy ranges, the one which produced the smallest error box was chosen to represent the source position, as long as was greater than 4, a level chosen to reflect a reasonable degree of confidence in the detection. ...

Next: Publication Costs of Astronomical Research . ... Purple Mountain Observatory, Academia Sinica, Nanjing 210008, China, e-mail: library@nanjing.jspta.chinamail.sprint.com . This article includes a general overview of the Purple Mountain Observatory (PMO) followed by a description of the document resources held in the Observatory Library. ... The predecessor of the Observatory was the National Research Institute of Astronomy in the former Academia Sinica and its observing site, the PMO. ...

. XMM-Newton Science Analysis System . ssclib (ssclib-3.29.3) [xmmsas_20070708_1801-7.1.0] . Meta Index / Home Page . Module name: source_cutouts . Author: Ian Stewart (University of Leicester, ims@star.le.ac.uk) . XMM-Newton SOC/SSC -- 2007-07-08

... Natalya V. Raguzova and Sergei B. Popov . ... We present a compilative catalogue of Be/X-ray binaries and candidates in the Galaxy and in the Large and Small Magellanic Clouds. This catalogue contains 160 sources and provides information on names and spectral types of optical components, distances, on spin characteristics of neutron stars, and on orbital and X-ray properties of binary systems. ... Be/X-Ray Binaries and candidates in the Galaxy . Galactic sources: comments to the Table 1 . ...

Next: Photometry Up: Regions and Source Parameters Previous: *imcnts* - Find counts . This task (developed for use with optical images, but also useful with x-ray data) will quickly compute location, size, ellipticity, and position angle of sources. ... User can generate contour plots of any portion of the image and count rates in slices through the image. The program is advertised as ``quick [optical] photometry''. input file: rp110590_im1.imh . output file: logfile . ... Photometry . ...

... The formation of multiple images of a distant quasar by the gravitational lensing effect of a foreground galaxy may be very simply, and faithfully, accounted for by a wine glass experiment. Figure 1. In the wine glass experiment, a bright compact light source (at the top of the photo) serves as a distant quasar. The wine glass on the table distorts the light rays from the "quasar" and produces a caustic having with a triangular shape (see enlargement in Figure 3 ). ...