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A γ-ray burst at a redshift of z ≈ 8.2


Long-duration γ-ray bursts (GRBs) are thought to result from the explosions of certain massive stars1, and some are bright enough that they should be observable out to redshifts of z > 20 using current technology2,3,4. Hitherto, the highest redshift measured for any object was z = 6.96, for a Lyman-α emitting galaxy5. Here we report that GRB 090423 lies at a redshift of z ≈ 8.2, implying that massive stars were being produced and dying as GRBs 630 Myr after the Big Bang. The burst also pinpoints the location of its host galaxy.

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Figure 1: Multiband images of the afterglow of GRB 090423.
Figure 2: The composite infrared spectrum of the GRB 090423 afterglow.
Figure 3: The X-ray and infrared light curves of GRB 090423.

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We thank Ph. Yock, B. Allen, P. Kubanek, M. Jelinek and S. Guziy for their assistance with the BOOTES-3 YA telescope observations (Supplementary Information). This work was partly based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the US National Science Foundation on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), the Ministério da Ciência e Tecnologia (Brazil) and SECYT (Argentina). This work was also partly based on observations made using ESO telescopes at the La Silla or Paranal observatories by G. Carraro, L. Schmidtobreick, G. Marconi, J. Smoker, V. Ivanov, E. Mason and M. Huertas-Company. The UKIRT is operated by the Joint Astronomy Centre on behalf of the UK Science and Technology Facilities Council. R.J.F. acknowledges a Clay Fellowship.

Author Contributions Triggering observations: N.R.T., D.B.F., A.J.L., E.B., J.S.B., D.P., J. Greiner, A.J.C.-T., A.d.U.P.; analysis of ground-based data: N.R.T., D.B.F., A.J.L., E.B., K.W., J.P.U.F., A.C., J.S.B., J.F., J.D., J. Gorosabel, B.C., D.P., J.R.M., T. Krühler, A.J.C.-T., A.d.U.P., C.G.M.; Swift analysis: P.A.E., R.L.C.S., K.P., R.W., A.J.L., N.R.T., N.G., D.W., P.S., T.S.; observations at various observatories and their automation to accept GRB overrides: A.J.A., A.A., T. Kerr, T.N., A.W.S., K.R., T.W. All authors made contributions through their involvement in the programmes from which the data derive, and contributed to the interpretation, content and discussion presented here. Writing was led by N.R.T., A.J.L., D.B.F. and E.B.

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Correspondence to N. R. Tanvir.

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This file contains Supplementary Methods and Notes, Supplementary Data, Supplementary Tables S1-S3, Supplementary Figures S01-S06 with Legends and Supplementary References. (PDF 1507 kb)

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Tanvir, N., Fox, D., Levan, A. et al. A γ-ray burst at a redshift of z ≈ 8.2. Nature 461, 1254–1257 (2009).

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