GRB 970228

GRB 970228 was a gamma-ray burst (GRB). It was the first GRB which had an afterglow. It was seen on 28 February 1997. Since 1993, scientists had predicted GRBs to be followed by afterglows. But, until this event, GRBs had only been seen in very bright bursts of high-energy gamma rays.

The burst had several peaks in its light curve. It lasted around 80 seconds. The light curve was not normal. This suggested that a supernova may have happened as well. GRB 970228 happened in the same place as a galaxy about 8.1 billion light-years away. This means that GRBs happen outside the Milky Way.

 Cause 
Reichart showed that the light curve of GRB 970228 could only have been caused by a supernova.Reichart, Daniel E. 2001. Light curves and spectra of dust echoes from gamma-ray bursts and their afterglows: continued evidence that GRB 970228 is associated with a supernova. Astrophysical Journal 554 (2): 649–659.  Definitive evidence linking gamma-ray bursts and supernovae was eventually found in the spectrum of GRB 020813,Butler, Nathaniel R. et al 2003. The X-ray afterglows of GRB 020813 and GRB 021004 with Chandra HETGS: possible evidence for a supernova prior to GRB 020813. Astrophysical Journal 597 (2): 1010–1016.  and the afterglow of GRB 030329.Stanek, Krzysztof Z. et al 2003. Spectroscopic discovery of the supernova 2003dh associated with GRB0303291. Astrophysical Journal 591 (1): L17–L20.  However, supernova-like features only become apparent in the weeks following a burst, leaving the possibility that very early luminosity variations could be explained by dust echoes. Moran, Jane A. and Reichart, Daniel E. 2005. Gamma-ray burst dust echoes revisited: expectations at early times. Astrophysical Journal 632 (1): 438–442. 

 References 

Other websites
Gamma-ray Burst 970228
BeppoSAX follow-up observations of the region of the Gamma-ray burst GRB 970228 

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