GRB 970228
GRB 970228 was the first gamma-ray burst (GRB) for which an afterglow was observed. It was detected on 28 February 1997 at 02:58 UTC. Since 1993, physicists had predicted GRBs to be followed by a lower-energy afterglow (in wavelengths such as radio waves, x-rays, and even visible light), but until this event, GRBs had only been observed in highly luminous bursts of high-energy gamma rays (the most energetic form of electromagnetic radiation); this resulted in large positional uncertainties which left their nature very unclear.
| Event type | Gamma-ray burst |
|---|---|
| Constellation | Orion |
| Right ascension | 05h 01m 46.7s |
| Declination | +11° 46′ 53.0″ |
| Epoch | J2000 |
| Distance | 8,123,000,000 ly (2.491×109 pc) |
| Redshift | 0.695, 0.695 |
| Total energy output | 5.2×1044 J |
| Other designations | GRB 970228 |
| Related media on Commons | |
The burst had multiple peaks in its light curve and lasted approximately 80 seconds. Peculiarities in the light curve of GRB 970228 suggested that a supernova may have occurred as well. The position of the burst coincided with a galaxy about 8.1 billion light-years away (a redshift of z = 0.695), providing early evidence that GRBs occur well beyond the Milky Way; this was proven decisively two months later with a subsequent burst GRB 970508.