Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Early optical emission from the γ-ray burst of 4 October 2002


Observations of the long-lived emission—or ‘afterglow’—of long-duration γ-ray bursts place them at cosmological distances, but the origin of these energetic explosions remains a mystery. Observations of optical emission contemporaneous with the burst of γ-rays should provide insight into the details of the explosion, as well as into the structure of the surrounding environment. One bright optical flash was detected during a burst1, but other efforts2,3 have produced negative results. Here we report the discovery of the optical counterpart of GRB021004 only 193 seconds after the event. The initial decline is unexpectedly slow and requires varying energy content in the γ-ray burst blastwave over the course of the first hour. Further analysis of the X-ray and optical afterglow suggests additional energy variations over the first few days.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Optical images of GRB021004.
Figure 2: Optical light curve of the afterglow of GRB021004 (refs 6, 22–24) alongside other well-studied afterglows taken from the literature.
Figure 3: Direct comparison of the X-ray and optical light curves of the afterglow of GRB021004.


  1. Akerlof, C. et al. Observation of contemporaneous optical radiation from a gamma-ray burst. Nature 398, 400–402 (1999)

    Article  ADS  CAS  Google Scholar 

  2. Williams, G. G. et al. LOTIS search for early-time optical afterglows: GRB 971227. Astrophys. J. 519, L25–L29 (1999)

    Article  ADS  Google Scholar 

  3. Kehoe, R. et al. A search for early optical emission from short- and long-duration gamma-ray bursts. Astrophys. J. 554, L159–L162 (2001)

    Article  ADS  Google Scholar 

  4. Shirasaki, Y. et al. GRB021004(= H2380): a long GRB localized by HETE in near-real time. GRB Circ. Netw. 1565, 1 (2002)

    ADS  Google Scholar 

  5. Fox, D. W. GRB021004: optical afterglow. GRB Circ. Netw. 1564, 1 (2002)

    ADS  MathSciNet  Google Scholar 

  6. Uemura, M., Ishioka, R., Kato, T. & Yamaoka, H. GRB 021004: Kyoto observation. GRB Circ. Netw. 1566, 1 (2002)

    ADS  Google Scholar 

  7. Matsumoto, K., Kawabata, T., Ayani, K., Urata, Y. & Yamaoka, H. GRB021004: optical observations at Bisei. GRB Circ. Netw. 1567, 1 (2002)

    ADS  Google Scholar 

  8. Fox, D. W. et al. GRB021004: absorption redshift. GRB Circ. Netw. 1569, 1 (2002)

    ADS  MathSciNet  Google Scholar 

  9. Chornock, R. & Filippenko, A. V. GRB 021004 redshift. GRB Circ. Netw. 1605, 1 (2002)

    ADS  Google Scholar 

  10. Berger, E., Kulkarni, S. R. & Frail, D. A. GRB 021004: Unusual radio-to-submm spectrum. GRB Circ. Netw. 1612, 1 (2002)

    ADS  Google Scholar 

  11. Kulkarni, S. R. et al. The afterglow, redshift and extreme energetics of the gamma-ray burst of 23 January 1999. Nature 398, 389–394 (1999)

    Article  ADS  CAS  Google Scholar 

  12. Briggs, M. S. et al. Observations of GRB 990123 by the Compton Gamma Ray Observatory. Astrophys. J. 524, 82–91 (1999)

    Article  ADS  CAS  Google Scholar 

  13. Lamb, D. et al. HETE fluences for GRB021004. GRB Circ. Netw. 1600, 1 (2002)

    ADS  Google Scholar 

  14. Sari, R. & Piran, T. Predictions for the very early afterglow and the optical flash. Astrophys. J. 520, 641–649 (1999)

    Article  ADS  Google Scholar 

  15. Chevalier, R. A. & Li, Z. Wind interaction models for gamma-ray burst afterglows: The case for two types of progenitors. Astrophys. J. 536, 195–212 (2000)

    Article  ADS  Google Scholar 

  16. Kobayashi, S. & Zhang, B. GRB021004: Reverse shock emission. Astrophys. J. 582, L75–L78 (2003)

    Article  ADS  Google Scholar 

  17. Nakar, E., Piran, T. & Granot, J. Variability in GRB Afterglows and GRB 021004. New Astron. (submitted); preprint at 〈〉 (2002)

  18. Lazzati, D., Rossi, E., Covino, S., Ghisellini, G. & Malesani, D. The afterglow of GRB 021004: surfing on density waves. Astron. Astrophys. 396, L5–L9 (2002)

    Article  ADS  Google Scholar 

  19. Heyl, J. S. & Perna, R. Broadband modeling of GRB 021004. Astrophys. J. Lett. (in the press); preprint at 〈〉 (2002)

  20. Granot, J. & Sari, R. The shape of spectral breaks in gamma-ray burst afterglows. Astrophys. J. 568, 820–829 (2002)

    Article  ADS  CAS  Google Scholar 

  21. Henden, A. GRB021004, BVRcIc field photometry. GRB Circ. Netw. 1583, 1 (2002)

    ADS  Google Scholar 

  22. Holland, S. T. et al. Optical photometry of GRB 021004: The first month. Astrophys. J. (in the press); preprint at 〈〉 (2002)

  23. Pandey, S. B. et al. Optical observations of the bright long duration peculiar GRB 021004 afterglow. Bull. Astron. Soc. India (submitted); preprint at 〈〉 (2002)

  24. Bersier, D. et al. The unusual optical afterglow of the gamma-ray burst GRB 021004: Color changes and short-time-scale variability. Astrophys. J. 584, L43–L46 (2003)

    Article  ADS  Google Scholar 

  25. Park, H. S., Williams, G. & Barthelmy, S. GRB021211 (HETE2493), OT at 143 sec. GRB Circ. Netw. 1736, 1 (2002)

    ADS  Google Scholar 

  26. Wozniak, P. et al. GRB021211: Measurement of early time afterglow. GRB Circ. Netw. 1757, 1 (2002)

    ADS  Google Scholar 

  27. Li, W., Filippenko, A. V., Chornock, R. & Jha, S. The early light curve of the optical afterglow of GRB021211. Preprint at 〈〉 (2003)

  28. Fox, D. W. et al. Discovery of early optical emission from GRB021211. Preprint at 〈〉 (2003)

Download references


We thank D. L. Kaplan and C. Trujillo for assistance with supporting observations at Palomar and R. D. Blandford for discussions. The results presented in this paper are based on data obtained using the NASA-JPL CCD camera at the Oschin Telescope, Palomar Observatory, California Institute of Technology (Caltech). The research was performed in part by the Jet Propulsion Laboratory, Caltech, under contract with the National Aeronautics and Space Administration (NASA). γ-ray burst research at Caltech is supported in part by funds from NSF and NASA.

Author information

Authors and Affiliations


Corresponding author

Correspondence to D. W. Fox.

Ethics declarations

Competing interests

The authors declare that they have no competing financial interests.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Fox, D., Yost, S., Kulkarni, S. et al. Early optical emission from the γ-ray burst of 4 October 2002. Nature 422, 284–286 (2003).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing