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117 results on '"Shrader, C. R"'

105. Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. 5: Variability of the ultraviolet continuum and emission lines of NGC 3783

Author

Reichert, G. A., primary, Rodriguez-Pascual, P. M., additional, Alloin, D., additional, Clavel, J., additional, Crenshaw, D. M., additional, Kriss, G. A., additional, Krolik, J. H., additional, Malkan, M. A., additional, Netzer, H., additional, Peterson, B. M., additional, Wamsteker, W., additional, Altamore, A., additional, Altieri, B., additional, Anderson, K. S., additional, Blackwell, J. H., Jr., additional, Boisson, C., additional, Brosch, N., additional, Carone, T. E., additional, Dietrich, M., additional, England, M. N., additional, Evans, I. N., additional, Filippenko, A. V., additional, Gaskell, C. M., additional, Goad, M., additional, Gondhalekar, P. M., additional, Horne, K., additional, Kazanas, D., additional, Kollatschny, W., additional, Koratkar, A. P., additional, Korista, K. T., additional, MacAlpine, G. M., additional, Maoz, D., additional, Mazeh, T., additional, McCollum, B., additional, Miller, H. R., additional, Mendes de Oliveira, C., additional, O'Brien, P. T., additional, Pastoriza, M. G., additional, Pelat, D., additional, Perez, E., additional, Perola, G. C., additional, Pogge, R. W., additional, Ptak, R. L., additional, Recondo-Gonzalez, M. C., additional, Rodriguez-Espinosa, J., additional, Rosenblatt, E. I., additional, Sadun, A. C., additional, Santos-Lleo, M., additional, Shields, J. C., additional, Shrader, C. R., additional, Shull, J. M., additional, Simkin, S. M., additional, Sitko, M. L., additional, Snijders, M. A. J., additional, Sparke, L. S., additional, Stirpe, G. M., additional, Stoner, R., additional, Storchi-Bergmann, T., additional, Sun, W.-H., additional, Wang, T., additional, Welsh, W. F., additional, White, R. J., additional, Winge, C., additional, and Zheng, W., additional

Published
1994
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106. The multifrequency spectral evolution of blazar 3C 345

Author

Webb, J. R., primary, Shrader, C. R., additional, Balonek, T. J., additional, Crenshaw, D. M., additional, Kazanas, D., additional, Clements, S., additional, Smith, A. G., additional, Nair, A. D., additional, Leacock, R. J., additional, Gombola, P. P., additional, Sadun, A., additional, Miller, H. R., additional, Robson, I., additional, Fujimoto, R., additional, Makino, F., additional, Kii, T., additional, Aller, H., additional, Aller, M., additional, Hughes, P., additional, Valtaoja, E., additional, Teraesranta, H., additional, Salonen, E., additional, Tornikoski, M., additional, and Chism, W., additional

Published
1994
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113. The 2005 outburst of GRO J1655−40: spectral evolution of the rise, as observed by Swift.

Author

Brocksopp, C., McGowan, K. E., Krimm, H., Godet, O., Roming, P., Mason, K. O., Gehrels, N., Still, M., Page, K., Moretti, A., Shrader, C. R., Campana, S., and Kennea, J.

Subjects
SUPERMASSIVE black holes, GRAVITATIONAL collapse, STARS, X-ray spectroscopy, SPECTRUM analysis, ASTRONOMY, PHYSICAL sciences
Abstract

We present Swift observations of the black hole X-ray transient, GRO J1655−40, during the recent outburst. With its multiwavelength capabilities and flexible scheduling, Swift is extremely well suited for monitoring the spectral evolution of such an event. GRO J1655−40 was observed on 20 occasions and data were obtained by all instruments for the majority of epochs. X-ray spectroscopy revealed spectral shapes consistent with the ‘canonical’ low/hard, high/soft and very high states at various epochs. The soft X-ray source (0.3–10 keV) rose from quiescence and entered the low/hard state, when an iron emission line was detected. The soft X-ray source then softened and decayed, before beginning a slow rebrightening and then spending ∼3 weeks in the very high state. The hard X-rays (14–150 keV) behaved similarly but their peaks preceded those of the soft X-rays by up to a few days; in addition, the average hard X-ray flux remained approximately constant during the slow soft X-ray rebrightening, increasing suddenly as the source entered the very high state. These observations indicate (and confirm previous suggestions) that the low/hard state is key to improving our understanding of the outburst trigger and mechanism. The optical/ultraviolet light curve behaved very differently from that of the X-rays; this might suggest that the soft X-ray light curve is actually a composite of the two known spectral components, one gradually increasing with the optical/ultraviolet emission (accretion disc) and the other following the behaviour of the hard X-rays (jet and/or corona). [ABSTRACT FROM AUTHOR]

Published
2006
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115. Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. V. Variability of the ultraviolet continuum and emission lines of NGC 3783

Author

Reichert, G. A., Rodríguez-Pascual, P. M., Alloin, D., Clavel, J., Crenshaw, D. M., Kriss, G. A., Krolik, J. H., Malkan, M. A., Netzer, H., Peterson, B. M., Wamsteker, W., Altamore, A., Altieri, B., Anderson, K. S., Blackwell Jr, J. H., Boisson, C., Brosch, N., Carone, T. E., Dietrich, M., England, M. N., Evans, I. N., Filippenko, A. V., Gaskell, C. M., Goad, M., Gondhalekar, P. M., Horne, K., Kazanas, D., Kollatschny, W., Koratkar, A. P., Korista, K. T., Macalpine, G. M., Maoz, D., Mazeh, T., Mccollum, B., Miller, H. R., Mendes Oliveira, C., O Brien, P. T., Pastoriza, M. G., Pelat, D., Pérez, E., Perola, G. C., Pogge, R. W., Ptak, R. L., Recondo-González, M. C., Rodríguez-Espinosa, J., Rosenblatt, E. I., Sadun, A. C., Santos-Lléo, M., Shields, J. C., Shrader, C. R., Shull, J. M., Simkin, S. M., Sitko, M. L., Snijders, M. A. J., Sparke, L. S., Giovanna Maria Stirpe, Stoner, R., Storchi-Bergmann, T., Sun, W. -H, Wang, T., Welsh, W. F., White, R. J., Winge, C., and Zheng, W.

Subjects
Galáxia NGC 5548, Seyfert [Galaxies], active [Galaxies], nuclei [Galaxies], Espectros astronômicos, individual (NGC 3783) [Galaxies], Galaxias seyfert, Nucleo galatico, Galáxia NGC 3783, galaxies [Ultraviolet]
Abstract

We report on the results of intensive ultraviolet spectral monitoring of the Seyfert 1 galaxy NGC 3783. The nucleus of NGC 3783 was observed with the International Ultraviolet Explorer satellite on a regular basis for a total of 7 months, once every 4 days for the first 172 days and once every other day for the final 50 days. Significant variability was observed in both continuum and emission-line ftuxes. The light curves for the con­ tinuum ftuxes exhibited two well-defined local mínima or "dips," the first lasting

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