| dc.creator | Shaposhnikov, Nikolai | |
| dc.creator | Zhang, Xiao-Ling | |
| dc.creator | Diehl, Roland | |
| dc.creator | von Kienlin, Andreas | |
| dc.creator | Swartz, Doug | |
| dc.creator | Wilson-Hodge, Colleen A. | |
| dc.creator | Cherry, Michael L. | |
| dc.creator | Case, Gary L. | |
| dc.creator | Baumgartner, Wayne H. | |
| dc.creator | Beklen, Elif | |
| dc.creator | Bhat, P. Narayana | |
| dc.creator | Briggs, Michael S. | |
| dc.creator | Camero-Arranz, Ascension | |
| dc.creator | Chaplin, Vandiver | |
| dc.creator | Connaughton, Valerie | |
| dc.creator | Finger, Mark H. | |
| dc.creator | Gehrels, Neil | |
| dc.creator | Greiner, Jochen | |
| dc.creator | Jahoda, Keith | |
| dc.creator | Jenke, Peter | |
| dc.creator | Kippen, R. Marc | |
| dc.creator | Kouveliotou, Chryssa | |
| dc.creator | Krimm, Hans A. | |
| dc.creator | Kuulkers, Erik | |
| dc.creator | Lund, Niels | |
| dc.creator | Meegan, Charles A. | |
| dc.creator | Natalucci, Lorenzo | |
| dc.creator | Paciesas, William S. | |
| dc.creator | Preece, Robert | |
| dc.creator | Rodi, James C. | |
| dc.creator | Skinner, Gerald K. | |
| dc.date | 2011-02-01T01:00:00Z | |
| dc.date.accessioned | 2021-12-03T12:04:55Z | |
| dc.date.available | 2021-12-03T12:04:55Z | |
| dc.identifier | f0946d4f-ab48-478d-8761-2eb5ed58d8da | |
| dc.identifier | 10.1088/2041-8205/727/2/l40 | |
| dc.identifier | https://avesis.sdu.edu.tr/publication/details/f0946d4f-ab48-478d-8761-2eb5ed58d8da/oai | |
| dc.identifier.uri | http://acikerisim.sdu.edu.tr/xmlui/handle/123456789/95746 | |
| dc.description | The Crab Nebula is the only hard X-ray source in the sky that is both bright enough and steady enough to be easily used as a standard candle. As a result, it has been used as a normalization standard by most X-ray/gamma-ray telescopes. Although small-scale variations in the nebula are well known, since the start of science operations of the Fermi Gamma-ray Burst Monitor (GBM) in 2008 August, a similar to 7% (70 mCrab) decline has been observed in the overall Crab Nebula flux in the 15-50 keV band, measured with the Earth occultation technique. This decline is independently confirmed in the similar to 15-50 keV band with three other instruments: the Swift Burst Alert Telescope (Swift/BAT), the Rossi X-ray Timing Explorer Proportional Counter Array (RXTE/PCA), and the Imager on-Board the INTEGRAL Satellite (IBIS). A similar decline is also observed in the similar to 3-15 keV data from the RXTE/PCA and in the 50-100 keV band with GBM, Swift/BAT, and INTEGRAL/IBIS. The pulsed flux measured with RXTE/PCA since 1999 is consistent with the pulsar spin-down, indicating that the observed changes are nebular. Correlated variations in the Crab Nebula flux on a similar to 3 year timescale are also seen independently with the PCA, BAT, and IBIS from 2005 to 2008, with a flux minimum in 2007 April. As of 2010 August, the current flux has declined below the 2007 minimum. | |
| dc.language | eng | |
| dc.rights | info:eu-repo/semantics/closedAccess | |
| dc.title | WHEN A STANDARD CANDLE FLICKERS | |
| dc.type | info:eu-repo/semantics/article |
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