Astronomy Picture of the Day

Explanation: Do the powerful explosions known as gamma-ray bursts (GRBs) originate in galaxies? This subject took on new light yesterday with the release of a Hubble Space Telescope image of the sky surrounding GRB 990123. This burst was first detected only two weeks ago and catalogued as one of the most powerful GRBs ever. The optical transient (OT) counterpart to the GRB can be seen as the bright spot just below centre. Once so bright it was briefly visible with just binoculars, this OT has since become four million times dimmer and continues to fade. Now, it can be seen easily with only a large telescope. The diffuse object above is of particular interest because it appears to be the host galaxy of GRB 990123. This distant galaxy seems to have a normal brightness but an irregular shape. This discovery increases the evidence that most OTs do occur in galaxies. Are all host galaxies this strange?