Diamond Jubilee Debate Glossary

Gamma-Ray Burst, or GRB, refers to a burst of gamma-rays from space that can last from a fraction of a second to many minutes. The cause and even the distance of these bursts remain uncertain. A key topic of discussion in the 1995 "Diamond Jubilee" debate was the distance of GRBs.

Cepheids are pulsating variable stars whose period of pulsation is directly related to their intrinsic brightness. This period-luminosity relationship was a point of contention during the 1920 Curtis-Shapley debate.

Compton Gamma Ray Observatory, or Compton for short, was the second of NASA's Great Observatories. The satellite housed four gamma-ray instruments - BATSE, COMPTEL, EGRET, and OSSE. COMPTEL, the imaging COMPton TELescope, detected several GRBs with positions more accurate than BATSE's. OSSE, the Oriented Scintillation Spectroscopy Experiment, detected many GRBs with its shields at energies above BATSE's primary sensitivity.

Gamma-ray bursts are also known as isolated bright events on the gamma-ray sky at energies above about 10 keV. The degree of isotropy of the distribution of GRB events on the sky is a topic of debate. GRBs can sometimes exhibit cyclotron lines, but the existence and significance of these lines in GRB spectra is controversial.

The Compton Observatory's four gamma-ray instruments were BATSE, COMPTEL, EGRET, and OSSE. The Compton Observatory was named after Nobel Laureate Arthur Holly Compton, a physicist known for his work on high energy photon scattering. BATSE, the Burst and Transient Source Experiment, is an all-sky monitor with 8 detectors. The Burst and Transient Source Experiment, or BATSE, has accumulated more GRB data than all previous GRB experiments combined.