FIGURE 2.10 Observations at many wavelengths are needed to understand gamma-ray bursts. This gamma-ray burst was discovered by the Compton Gamma Ray Observatory (CGRO) on January 23, 1999. The optical flash from the gamma-ray burst was observed by the Robotic Optical Transient Search Experiment (ROTSE) 22 seconds later. Subsequently, the BeppoSAX satellite detected the x-ray emission from the burst. Based on preliminary information from BeppoSAX, astronomers at the Palomar Observatory identified the precise location. Astronomers at one of the Keck telescopes were then able to obtain the spectrum and determine the distance. Within a day, radio astronomers used the Very Large Array to observe the fading afterglow of the burst. After 17 days, the burst had faded enough so that astronomers using the Hubble Space Telescope could observe the host galaxy. This is probably the most energetic gamma-ray burst ever recorded. Images courtesy of NASA, CGRO BATSE Team, ROTSE Project, J. Bloom (Caltech), BeppoSAX GRB Team, W.M. Keck Observatory, NSF/NRAO, A. Fruchter (STScI), and P. Tyler (NASA GSFC).